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BMW Press (de la 6)

Vendue à plus de 31 000 unités au cours des années 90, la série 8 a représente une nouvelle étape-clé dans l’histoire du coupé BMW : ses moteurs à huit et à douze cylindres catapultaient allègrement la série 8 à une vitesse pouvant atteindre 250 kilomètres/heure et permettaient à la communauté exclusive de ses adeptes de savourer un plaisir de conduire passionné, inédit à cette époque.

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Le coupé série 8 possède pour commencer une ligne bien personnelle, dont les gènes de la M1 se retrouvent partiellement dans sa ligne fluide signée Klaus Kapitza.

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Eléments fondamentaux d'un haut de gamme, le luxe passe aussi par un équipement technologique important.

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Produit à seulement 1510 exemplaires de 1992 à 1996, la Bmw 850 CSi est une voiture rare... Avis aux amateurs !

BMW's V-12 hydraulic camshaft chain tensioner contains an O-ring that hardens over time and allows oil to seep past the O-ring and out through the tension adjustment screw threads. This results in small puddles of oil on the garage floor and an oil-soaked A/C compressor and drive belt. This slow leakage does not affect the operating performance of the tensioner.

The tensioner is located on the right front of the engine, directly above the A/C compressor. Most tensioners still have their “anti-tampering” cap in place, a black cylindrical plastic cap to protect the adjustment screw from damage. Oil typically weeps along the adjustment screw and exits the tensioner at the end of this cap, which is open. Some tensioners have their protection cap missing, exposing the adjustment screw and lock nut.
Here's a schematic of the entire assembly:

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1. Tension set screw
2. Set screw lock nut (17mm)
3. Screw plug (19 mm)
4. Aluminum crush sealing ring (07 11 9 963 355)
5. Dowell sleeve O-ring (11 31 1 702 953)
6. Dowell sleeve
7. Spring
8. Piston

You'll need to purchase items 4 and 5 above, and also the anti-tampering cover (11 31 1 720 006), which is not shown. You also need 17mm and 19mm deep sockets and a torque wrench calibrated up to 50 NM.
The picture below shows the location of the tensioner cap assembly on the engine, just forward of the air conditioning compressor on the right, front, lower section of the engine.

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To gain access, remove the intake mass airflow sensor and rubber ducting between the air cleaner housing and the DK motor assembly. Also, disconnect the high tension lead from the coil and carefully put aside. You'll need to remove the protection cap (item 1 below left) by vigorously wiggling from side to side. It can't be reused, so don't worry about damaging it.

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Next, take your 17mm socket and release the tensioner set screw locknut (item 2 above). Leave it loose on the set screw (item 1) and give the set screw precisely 1 counterclockwise turn to release a tiny bit of pressure off the tensioner piston. Don't disturb the set screw any further, and gently snug the lock nut back down onto the screw plug (item 3).
Next, get your 19mm deep socket, fit over the screw plug, and giving a mighty heave, unscrew the plug. Do not release the plug entirely from the cylinder block. The piston inside is under considerable pressure and will definitely damage hands if you're not prepared to press against it when the screw threads release. Slowly unscrew the plug. When it releases, a capful of oil will drain from the tensioner piston all over the floor, so be prepared to catch it. Once free, you might have to extract the piston (item from the bore by fishing around with your little finger.
Here's what it all looks like in the flesh:

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Now, using an Exacto knife, carefully nick and pry at the O-ring (item 5) on the dowell sleeve (6). Do not scratch or otherwise damage the dowell sleeve. The O-ring will be very hard and sealed in its groove. Once free, clean the groove, replace the O-ring, and replace the crush ring (item 4) on the screw plug.
Now, time to assemble everything. Insert the piston into the bore with the end of your little finger, and press and rotate until you feel the end of the piston "key" into the tensioner ramp. Here's a picture of the piston engaging the ramp below on the left in item 1.

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Now comes the hard part. Seat the narrow end of the spring (7) into the dowell sleeve (6), and seat the sleeve into the screw plug (3). I then put the screw plug into my 19mm socket, guided the spring into the back of the piston, and tried repeatedly to compress the spring enough to allow the screw plug to engage a thread on the cylinder block. It's really tough, so take your time. You'll get the hang of it after about 10 minutes. Once you've got it threaded, torque the screw plug down with 40 NM.
Next, turn the set screw 1 turn clockwise to restore the original tension setting, and tighten the 17 mm set screw (2) down with 20 NM torque (my guess - it's not in the specs). Place the protection cap on the set screw and wiggle it snug onto the screw plug.
Because you've drained a small catch reservoir the tensioner uses to feed oil to the piston, the tensioner will need to be primed. If the right camshaft cover is off, you can pour a small amount of oil down the right side of the camshaft front cover, where it will fill the reservoir. Then insert a long screwdriver (I used a wood paint mixing blade) and depress and release the tensioner ramp repeatedly until it becomes resistant to movement (see the A-B diagram above).
If you don't have the covers off and the tensioner ramp accessible, I've been told the following works pretty well. Set the OBC antitheft CODE feature of your car to disable the ignition, crank the engine three times for 10 seconds each time, and then disable the CODE feature to allow the engine to fire. You'll probably hear a lot of chain slap for the next 30 seconds while the reservoir fills and the tensioner piston primes. Degree of difficulty: 5 on a scale of 10.

Mark in SBA

OK, gentlemen -- Here's the scoop:

What's wrong with the V8 ? Courtesy of BMW Master Mechanic Brett Anderson http://www.koalamotorsport.com/v8shortblock.htm

BMW released the M60B30 and M60B40 V8's with the 93 model year 5,7 and 8 series. These engines ran until the 95 model year. From the 96 model year, they were replaced by the M62B44. The 3.0L was dropped in the US, but the rest of the world got the M62B35, a 3.5 litre V8.

There are many rumours about the fate of the M60 engine, but only one is true. The engines have been known to suffer damage to the cylinder bores from the excessive amounts of sulphur in the US fuels. The blocks are made of Nikasil, which is Aluminum impregnated with Nickel and Silicone. Apparently , sulphur reacts adversely with the Nickel , causing very slight blemishes in the top few millimetres of the cylinder bore. The cylinder bores are crosshatched, which is the name given to a pattern scratched into the surface of the cylinder wall. These scratches help seat and seal the piston rings, allowing good compression.

When the cylinder walls become damaged, the piston rings can no longer seal properly. As a result, the engine suffers from "leakdown". This is the term given for the amount of air that can escape past the piston as it attempts to compress the air into the combustion chamber. A near new engine , in good condition, should have a leakdown rating of approximately 5 8%. BMW's maximum allowable leakdown , on any engine, is 15%. Anything beyond that requires repair to the engine.

Leakdown can also be caused by poorly seated valves.

The problem in the V8's manifests itself as an EXCESSIVELY rough idle. These engines, due to their performance oriented cam shafts, have a noticeable "rock" at idle, this is completely normal. However, excessively rough idle will cause the entire car to shake, usually unevenly. The problem can also cause the engine to lose so much compression that it will no longer start.

While BMW was investigating the cause of the problem, several different methods of repair were tried.

First, they decided to raise the operating temperature of the engine, in an attempt to get a better burn of the gas, and therefore lessen the damage. The benefits of this campaign , which included replacement of the engine EPROM and thermostat, were negligible, if existent. However, they were an attempt to fix a problem that was not yet fully understood.

Once it was decided the engines needed to be opened and repairs made, the first try was installation of new pistons and rings, this was only tried on a few engines and was immediately dismissed as not viable.

Next step was to replace the short block assembly. This is what is still being done now, however, until the problem was 100 percent diagnosed by BMW, the replacement short blocks were of the same material as the original engines. This was not so much an oversight, but the only possible way of keeping cars on the road until a permanent solution could be found.

As a measure of good faith, BMW initiated an engine warranty, covering all internally lubricated parts, which includes the short block, for 100,000 miles, or 6 years. Until this, the engines were only covered under the standard 4 year 50,000 mile warranty.

Now, as the short blocks were being replaced with the same exact part, future problems could be expected without a doubt. The result of this situation is that some cars have had 2 and even 3 short block replacements.

As of early 1997, all replacement short blocks were of the new material, called Alusil. This material has been used in the V12 engines since their inception. No reason was given for the change to Nikasil, but I'd like to bet that guy no longer has a job. Anyway, Alusil does not suffer the same problem as Nikasil and if the Alusil short block has been installed, you no longer need to worry about the situation.

How do you tell which material is in your short block ?

That part is fairly easy. But it requires getting under the right front of the car. All M60 and M62 blocks have casting numbers on the right side, directly alongside the 3rd cylinder, slightly above the coolant drain bolt.

These are the casting numbers to look for :

Nikasil M60B30 1 725 970 or 1 741 212
Nikasil M60B40 1 725 963 or 1 742 998
Alusil M60B30 1 745 871
Alusil M60B40 1 745 872
Alusil M62B44 1 745 873
NOTE: All M62 engines are Alusil.

This is the only way to determine which M60 you have, short of removing a cylinder head.

In performing engine repairs or rebuild procedures in the future, it is imperative that you correctly identify the cylinder block, as the pistons and rings used in each style are different and not interchangeable.

What do I do if my engine idles rough ?

If you feel your M60 is idling roughly, make an appointment with your dealer for an idle quality check. This check is free, under the conditions of the 100,000 mile engine warranty. During this test, the technician hooks the car up to the BMW diagnostic computer system, which monitors the condition of the engine. If, during this test, the computer finds that there is a potential problem, it will order the technician to perform a manual leakdown test. If the tech finds any ONE cylinder to have more than 15% leakdown, you will be advised of the need for a new short block. You will then be requested to either leave the vehicle, or make an appointment to bring the vehicle back. The dealer will require the car for approximately 5 days, during which , they are to make a rental or loaner car available to you. If you have the test performed, but the results do not show the need for a new engine, do not go running to the next dealer for a new test. The dealer gets paid by BMW for his time, however, repetitive testing will not be covered, so the second dealer will not get paid for his time. This is unfair to the dealer. If your car passes, but you feel it should fail, take it in for another test in a few months, not straight away.

Thomas Frederick

Changing out all of the little filters in the hydraulic fluid lines.
The parts CD shows four separate filters for AHK equipped 850's.

The first one is the one we all know about, located at the bottom of the fluid cannister in the engine compartment.

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This one is the primary filter and should be serviced at some point. You need a turkey baster to suction out all of the Pentosin in the cannister. Then remove the screen and other attaching parts, lift out the dirty filter, and replace with the new one. Reinstall hardware in reverse order of removal. Do not refill yet.

The second filter is located underneath the front engine screening tray which is attached to our cars between the radiator and engine block (i.e., the engine accessory belt cover). There is a small filter located in this housing.

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Here's a new one compared to the filthy one removed:

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To access the filter, first remove the bolt attaching the support bracket seen at the top right. Then using the appropriate size socket, unscrew the small cannister from the bottom. A small amount of fluid will be trapped in the cannister, so have a receptacle in hand to catch it unless you like cleaning hydraulic fluid off the floor. Note that every 850 should have this front small filter, and that BMW service training materials indicate that it is important to periodically R&R this one.

For those 850's equipped with AHK, the rear pump unit contains two filters. The main filter and it's housing is shown here.

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A comparison of a clean filter versus the removed filter:

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The housing screws into this receptacle on the main AHK pump unit:

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The final filter is located on the upper pump assembly of the AHK beneath the small rectangular cover:

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With the cover removed, it looks like this:

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This was a little tricky to remove since it is installed upside down in the housing. I used a small paper clip with a hook I bent into it to catch the lower edge of the metal filter bottom to pull it out. BTW, this is the exact same filter as was used at the front of the car. A separate service gasket set is available to seal this one back up.

After replacing all of the filters and closing everything back up, it's time to add replacement Pentosin. Remember there will be a fluid deficit in the small filter holding cannisters, so you will need to fill it up, start the car up to let the pump circulate the fluid, and then shut it down and recheck the level in the cannister. I had to top mine up to the required 20mm below the rim level, which is just slightly above the screen inside the cannister. Here's a picture of the fluid after replacement, topped up to the correct level:

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The fluid removed was quite black. I'm not really sure if it's black because of dirt in the system, the hoses losing some of their linings, or the mechanical action of the pump. But whatever the reason, I'm thinking a 6 year old car was a perfect candidate for some clean filters and fresh Pentosin.

Steve C

Continuing on with the intake manifold repair job, you should see the banjo bolt replacement.
Right now, let's get into the intake manifold gasket replacement and talk a little about heater hoses.

Head inlet faces

In the picture below you see the right head stripped of the intakes and gaskets, and ready to receive the new gasket set. You'll notice the camshaft oil pipe and new banjo bolts above the inlets if you look carefully. Also notice the cam drive chain over there on the left, and the heater water return pipe running down the length of the valley just below the inlets. The inlets are stuffed with lint-free paper to preclude yours truly from dropping something down into a cylinder.

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Intake manifold gaskets/spacers/isolators

Sorry about the strong afternoon light, but I needed a lot of contrast to show you the raised lip on the gaskets. These are the new gaskets being fit-checked and then fastened to the head using an M10 nut on the head studs. Notice the camshaft chain drive crossing the "bridge" from the bottom to the top in the picture. This is also a good shot of the oiling pipe and banjo bolts.

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As you can see, there's plenty of room to work once the manifolds are off the engine.

Heater hoses

While I had my intakes out and the camshaft covers off, I decided to replace my 10-year old heater hoses. Here's a good shot of the return hose from the firewall manifold to the return pipe in the engine valley. Notice the other two hoses as well - they go over to the water control valve and auxilliary pump.

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That large pipe there over on the left, underneath the heater return pipe is the main water return pipe routing the water from the back of both heads to the water pump. Also, check out the size of those cam lobes - this engine is way overdesigned.

Camshaft covers

Nice shot of the engine with the covers on, just prior to fitting up the intake manifolds. You get a good shot of the water return pipes. Also, check out the left distributor rotor, removed as I replace the spark plugs.

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Fitting the manifolds

Here the right intake manifold (located on the LEFT side of the engine, confusing, huh?) after bead blasting it clean of a lot of oil residue and gunk. It's hard to see, but just above the manifold, but below the cam cover are the fuel return pipes. They get screwed down with the same bolts that hold the manifold, so fit checking at this stage become important.

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Shows you just how LONG those intake runners are.

Right intake attached

Intake is on and torqued down. Look down the left inlets and you'll see some gold-colored intake valve guides. Yup, your staring directly at the back of the valves. Notice the two fuel rail mounting posts with the gold-colored allen bolts in place? We'll put those on later, since we need access to those bottom bolts on the intake gaskets. It gets tough to gain access to things once we add the left manifold.

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Also check out the fuel injector bores to the right of the gasket nuts. Injectors simply press-fit into these holes with oversized O-rings. Also brought up the fuel return hoses for the fuel pressure regulators, and the evaporative purge hoses through the chain bridge and into the valley.

More pictures later. Next installment - the secret trick to fastening the manifold bolts.

Replacement of the heater hoses, particularly where they connect to the firewall "manifold" is much easier when both the intakes and camshaft covers are removed. It's very tight in the space between the back of the cylinder heads and the firewall, so I took this opportunity to replace all the hoses. While they looked fine, squeezing them revealed they were starting to feel "crackly" due to the extreme heat present here while the engine runs.

Also, I used this opportunity to align the heater hose clamps properly so I could use an extension and flex drive coupling to gain access in the future without having to remove the cam covers. I tried gaining access to the clamps after the covers were in place, and I think I can loosen the clamps with everything in place. I hope I'll never have the opportunity.

Obviously, you must remove the intake manifolds before you can remove the cam covers. However, cover removal is very easy - simply undo all the nuts and carefully wiggle the covers off. I say carefully, since the cover contains an integrated air/oil separator tack-welded onto the bottom side. It's equipped with two very delicate "J" drains made from very small diameter piping that can become easily bent or broken during cover removal. Hence, careful wiggling of the cover for it to clear the camshaft bearing journals.

If you remove the cover, I strongly suggest replacement of the cover gaskets - even the new and improved versions are susceptible to heat damage and cracking after several years on the engine. Also, I used Hylomar, a liquid gasket prep, on any rubber-metal sealing surface. It remains tacky and pliable after several years - and is used by the British car DIYers to keep their trophies stuck together.

Total time to replace hoses: 1 hour.

Total time to remove intakes and covers: 2 hours.

Total time to replace covers and intakes: 3 hours.

Mark in SBA

As promised, here's some snaps from my intake gasket repair wrench fest these past two weeks. One big concern I had was the reported "loose banjo bolt" problems afflicting V-12s from the late eighties and early nineties. Well, sure enough, I removed my camshaft covers and discovered the right rear banjo bolt was finger loose.

Managed to ordered up the new and improved bolts, shown here with the locking compound applied. Also shown is the bottom side of the oiler pipe. Notice the small spray holes that line up with the cam lobes?

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Here's a close-up shot of the installed bolts and oil pipe.

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And here's a long shot of the left cam gallery ready to close up with a new gasket. That blue stuff is Hylomar, a gasket prep that never hardens and remains perpetually tacky. I used it anywhere there was a gasket/metal combo. Also notice the new intake spacers being fit-checked on the right bank. You'll notice a prominent ridge lines on the spacers that eventually crack and admit air on cold mornings.

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Mark in SBA

Ok, I just finished replacing the heater core in my dad's '94 840Ci. While this is fresh in my mid I thought I would outline the procedure, I'm going from memory here, so I will do the best hit all the sneaky stuff. The repair manual is really a nessecity here as well.

This not a job for the faint of heart. Also, I strongly suggest taking the time to place all fasteners back in their repspective holes as you go. It will make things go a lot easier on reassembly.

Also, I would advise that you label all connectors as you take things apart. There are an awful lot of wires, and some unused connectors, so labeling them helps to avoid any confusion.

Lastly, if you are about to tackle this, read through the entire procedure before starting to get an idea of what is involved.

Warning: If you run the car at anytime during this lengthy procedure you have to reconnect both air bags, otherwise you will trip an SRS fault that will have to be cleared by the dealer.

.5) Turn key on, Switch wipers on, Put windows down, open sunroof (for light), lower steering column. Remove fuse for power steering column. Shut key off. (ie leave steering column lowered and wipers vertical)

1) disconnect batteries (Single ground post near L.S. battery in trunk), leave trunk open (place rag or something over latch)

2) Remove left and right kick panels. Removal of the left kick panel requires removal of hood release lever. They will require some gentle persuasion to come out.

3) Remove left and right under-dash panels. These should come out fairly easily with the kick panels removed.

4) Remove left and right and lower dash trim. Start by gently prying these away from the dash closest to the doors. There are studs that hold them into plastic retainers. They require a good amount of effort and will make a pretty bad noise coming off. Also be careful when you get to the ones closest to the center of the dash. Pry them away by sticking a screwdriver or flat blade of some sort in behind them, other wise you may pull the stud(s) out of the trim panel.

Continue removing them from the center console by pulling, They are are held onto the console with Velcro! And I though Alfa's and Ferraris were bad as they are assembled with pop rivets.

4a) if any of the above mentioned studs pull out of the trim panel, you can make Martha Stewart proud, and use a hot-glue gun to reattach them.

5) Remove rear seats. They just lift out from the front edge.

6) Remove the center arm rest in the rear.

7) Remove e-brake boot. The base snaps out, as you work the boot of the lever by turning it inside out, you will see a zip tie that holds it on. Cut this off and remove the boot.

Note: The step 8 applies to the automatic transmission only, YMMV.

Remove the shift knob, and boot. The knob just pulls off, with a good tug. Use a rubber mallot to tap it back on. The boot snaps off towards the center of the opening.

8a) Remove the two screws that hold the plate on around the shifter.

8b) Remove the small retainer clip that holds the pin in the shifter to the gear indicator. A steady hand and a pair of tweezers helps here. Gently pry the black plastic clip up, and push the pin underneath to the right. It stays in the shift lever.

8c) Carefully lift the gear selector indicator assembly up, and disconnect the wires to it and the transmission mode switch.

9) remove radio and disconnect wires.

10) Remove OBC display unit and disconnect.

11) Remove two plugs at top of center console and remove screws.

12) You can now remove the center portion of the center console. Gently pry it down and out from the top first and then disengage it from the bottom.

13) Disconnect wires to the seat heater switches, the red thingy, climate control, temp sensor, and the ASC switch. You can now remove this piece from the car and add to the growing pile of parts.

14) Remove the various bins and compartments from the center console, including the ash tray. All the screws that hold the center console in should now be exposed. Remove the two screws at the rear the two or three in the middle (bottom), the four on the sides (bottom) and the four at the front that hold it to the dash. Remove the center console. (Pull the e-brake up as far as possible)

15) Open glove box, and remove the two screws that hold the black felt piece on, which is above the glove box, and below the air bag. You can now lift the cover that exposes the passenger side airbag. Remove the other two screws behind this, and remove the glove box lock/latch assembly. There is a piece behind the latch [Oops!]'y which will fall off, this just snaps back on, after it is lined up correctly.

16) The batteries are disconnected right? Remove the orange connector from it's holder (give it a twist a quarter turn or so), remove the four bolts that hold the air bag in place, remove the air bag and set it down carefully somewhere right side up.

17) You will see a tubular brace/bracket to which the air bag is attached. Follow this down towards the middle of the car. Remove the bottom most bolt (8mm, 13mm wrench). Alos, cut the two zip ties that hold the air bag wire to the brace ... carefully.

18) Look behind the glove box. There is a wiring harness clipped to the back of the glove box, or near there. Disconnect the connector and make sure that the half of it that comes from the car is free from the dash. There is also a connector for the glove box lock, disconnect this as well. Now that I'm thinking about this removal of the glove box lock/latch [Oops!]'y in step 15 above is probably not required.

19) Remove lower steering column shroud. There is one screw that holds it on, loosen the screw and remove the screw and retainer. The shroud is clipped to the upper half. Some tugging is required.

20) You will see an orange connector under the steering column. Give it a quarter turn or so and remove it from it's holder. Disconnect the connector.

21) Remove two torx screws behind the steering wheel that hold the air bag on. Remove the air bag and set aside facing up carefully.

22) Remove bolt that holds the steering wheel on, make sure that the wheels are in the straioght-ahead position. You may want to make a pair of corresponding punch marks or somehow mark the wheel to the shaft so that you can put it back on in the proper position.

Note: Do not turn the slip ring independantly when the steering wheel is off. Also, when reinstalling the steering wheel, there is an index pin that fits into a corresponding hole in the back of the slip ring, make sure that is properly lined up/engaged.

23) Remove upper steering column shroud. Comes off the same way as the lower. You dropped the steering column before disconnecting the batteries, right? If not you can still get it out, but it is a lot harder, BTDT.

24) Remove two small screws from the top of the trim panel that surrounds the instrument cluster. There are two clips on either side that holds this in. A gentle pull on the trim, starting at the top and working around it should get it free. The two clips just slide into it so if you don't remove them they will fall out.

25) Carefully unplug all the switches ... Defroster, Fog lights, headlights, and dimmer wheel.

26) You will see two small philips head screws that hold the instrument cluster in place (at the top), remove these screws being careful to collect the cone-washers under the screws as well. You can now remove the instrument cluster from the dash, and remove the single connector.

27) Directly behind the instrument cluster you will see three bundles of wires, these are held to a 'frame' with two zip ties. Cut these zip ties, and pull these cables forward slightly. They will be in front a defroster duct which will come out with the dash.

28) Remove the four switches from the steering column and let the hang there. They are clipped in. There are some ears that you have to push/press to release them. You may have gently tug on the wiring harnesses that go to them slightly to get enough slack to extract them. Note the two pins (Air bag index, and horn contact) that are sticking out of the steerig column.

29) Remove the left and right 'A' Pillar trim. Pull it away slightly from the windshield at the top, and then up and it will come out. There is one clip near the top, and a tab that it fits into on the dash.

30) Remove the two pieces of foam that are at the bottom of where the trim that you just removed sits. It can be removed in-tact if you are careful, and put back in to prevent squeeks and rattles.

31) Remove the two small bolts that are in the corners of the dash. I used a 1/4" drive deep weel socket and a magnet to extract them. To put them back in, I used some dum-dum to hold the bolt into the socket, and some very dexterious fingers are required.

32) Remove the left most bottom bolt in the drivers side knee bolster.

33) Remove the two plugs that cover the bolts in the sides of the dash. (In door jambs) Remove the bolts, and the plastic cups that are behind them.

34) Remove the two screws at hold the lower edge of the dash to the knee bolster on the drivers side.

35) Remove the two bolts that hold the sides of the dash to the car. These are under the dash and go from the center of the car towards the outside.

36) Remove the bracket that is was held by the bolt that you just removed on the L.S., it might be stuck in place, this was also held by the left most lower bolt in the knee bolster.

37) Reach behind the dash through the intstrument pod opening, and there are two wires going to the center fresh air vents. One of them has a connector. Disconnect it. The other wires (there are two of them) go to the light for the fresh air vent dial. You have two choices ... You can cut the wires, and put a connector on them which is what I would suggest doing, or you can remove the vent assembly from the dash. There are three clips on the bottom and two on the top.(or is it the other way around?) You wil most likely break the small tabs in the plastic of the vent that hold the metal retainers into it when you try to remove it, I did. Hence I would suggest cutting the wires, they are just for a light.

If you opt to remove the dash vent from the dash, it has to go back in before the surround for the instrument cluster.

38) You are now ready to remove the dash. It pulls out to the rear, lifting slightly. Be careful of the two pins that I mentioned earlier in the steering column. Go slowly, and make sure that every thing is clear. Note the clip in the middle near the top, when reinstalling the dash, make sure that this properly engaged.

*Approx. Time so far, having never done this before 3.5hrs.

Yippee, now you are ready to tackle the heater core.

39) There is another tubular brace on the drivers side remove the bottom bolt near where the center console was, remove the bolt that holds it to the body all the way over on the left (there is a large zip tie that holds a million wires, cut this and carefully move the wires over a little), remove the two bolts that hold it to the steering column, and the two other bolts near the last two.

40) This is tricky, There are two more bolts that you have to remove that hold this brace to the steering column. Using a very long 13mm box wrench I was able to loosen them a little, and then using a 1/4" drive air ratchet remove them. The manual says to remove the two shear bolts that a little further up, that would be even more difficult.

41) you should now be able to move this brace slightly. You have to move it enough to clear the cover on the heater box. You may have to make a small slit in the carpeting, I did. It will be behind the console when it all goes back together, so it will not be visible.

42) Remove the two brackets at the bottom of the heater housing.

43) cut the zip ties that hold the wires to the cover on the heater housing, disconnect the two temp. sensors, and move all the wires out of the way. You may need to disconnect one or two of the flap motors on the right side.

44) Remove all the clips that hold the cover onto the heater housing. I think there are six or so. Remove the cover. There is a small foam gasket between the two halves, you may want to make sure that it is there. Half of mine fell out when I removed the cover, but I was able to fit back in, with little difficulty.

45) If you haven't already done so, drain the coolant. Disconnect the three heater hoses at the firewall and/or the heater valves. You can remove the 'cowling' that holds the micro air filters pretty easily on the 8 cylinder cars. Two bolts at the top, one on either side and it lifts right out. This gives more room to get to the hoses. Don't know about the 12 cylinder cars.

46) Using compressed air, at a fairly low pressure, blow out the three hoses/fittings. Otherwise you may make a little bit of a mess inside the car.

47) Remove the plastic double pipe from the metal pipes (one bolt) and the heater core (four bolts) and remove.

48) Remove the remaining bolt from the top of the heater core. This fitting (left most) requires a 1/4 turn or so to disengage the flange.

49) Remove heater core.

50) Install new Heater core. I got mine at the local dealer. Approx. 90.00 or so, and it included new 'o' rings for the fittings, as well as the foam insulation for the heater core. Getting the one flange back on with the new 'o' ring is a little tricky. You can do it with a pair of pliers, very carefully.

*Approx. Cumulative Time so far 7.5 hrs

51) As they say, reassembly is the reverse of removal. Now is a real good time to clean the windshield and the dash. Go slow, and make sure that everything is back together properly and all connectors are properly connected. Especially around the shifter, climate control and radio the routing of the wires is important so that nothing interferes with anything else. I had a problem with something rubbing against the fan in the back of the climate control unit. But I'm happy to say that there don't appear to be any rattles or squeeks.

*Close to another full day to put everything back together.

Jeff Greenfield

An update on the constant and niggling throttle hesitation problem on my '91 850i.

As you all know I for months have been dealing with a throttle hesitation problem that ultimately kicks in the "limp home" mode. My local dealer has had the car in its shop on at least five different occasions since September, 2000, and never fixed the problem. I sat at length with the service manager and the head mechanic and detailed the problem for them, but after all of these attempts and about $2,000.00 of my money, I got the car back the last time - after almost a month in their shop - with the same hesitation problem, but with newly cleaned injectors, two new O2 sensors, a new left air mass meter, two new distributor caps, a new thermostat and new plugs, all of which they at one time or the other claimed to be the cause of the problem. In short the problem was alleviated some but was still there - except my money wasn't.

[I hate to say it, but this is your typical stealer approach: replace parts one at a time hoping something will work. PMB]

Then the strangest thing happened - someone the the parts department who knew of me and my car's problems told me to get it out of the dealership (said they did not know what they were doing) and referred me to an independent mechanic - young 30ish "techno" type guy, and also said not to tell anyone as he might be fired for making this recommendation. I took my car to this new guy and just got my car back. It turned out to be a bad contact on one of the computer chips, so he ordered some kind of kit, or spray, to resolve the problem, and guess what - the car runs great and for the first time since September of last year, I have experienced no throttle hesitation at all after some heavy "shake down" driving in town last weekend, my "check engine" light has not come on, and my gas mileage has improved about 2 miles per gallon in the city. After a little digging, I found that most of the high end BMW's end up at this guys garage.

Moral of the story - a good mechanic is a necessity. Maybe my frustration level - and my wallet - will get a break, and I now again enjoy this wonderful machine.

[Perhaps this mechanic deserves a plug by name and city in case others on the list might wish to consult him? PMB]

JMMONTIJO

There are times in life, we have all been there, when you suddenly understand how lucky you are to be alive.

To pick up on this unbelievably true fable that has been going on mysteriously for a week or more concerning my steering wheel tilting suddenly to the left with no explanation even after checking all the steering etc. etc. I have many nice and informative e-mails from fellow owners and mechanics but it has still remained a mystery, until today.

I decided about 5:30 pm to head on down to the local market for some nice chicken breast, accompanying fruit & vegies and some nice dark Zinfindel to help it all slide down properly. As always in the last week it was impossible not to re-notice the lopsided steering wheel as I puttered along, as fast as the car is it is almost as much fun to drive slowly as fast. Each time I turned the wheel it was a constant re-examination as any of you would be doing, musing to myself about the unknown factor somehow involved.

I decided suddenly to go to a local German repair shop that is close to the market and of course pick up my food on the way back. I drove in just as they were closing and they exhibited the normal and expected show of appreciation and envy for the monster that purred into their cave of repair. The kind manager listened to my tail of woe and offered no explanations other than to say that he would need to check it out on the rack at a charge of $65, which would be used toward the cost of repair if I requested that he perform the needed mending.

I thought this fair and so I took his card and said I would call tomorrow and left quietly and slowly so as not to scrape the lovely and low-hung air-dam in the front. Then I decided suddenly to head for the other BMW repair shop that was nearby and see what that individual had to say. I haven't had the car long enough (2 months or more) to establish a relationship with anyone yet. So I puttered along on my way, the gas hungry monster that can swallow almost all other cars whole simply styling along in peace corps fashion while all cars whizzed by with all the drivers stretching their necks and smiling and waving at times.

Then I came to the shop and saw them closing their doors and I knew that I was a bit too late and would have to do all of this investigation properly tomorrow. So I purposely made some lazy turns and then fast turns in the large parking lot that was now empty and I started to notice for the first time that I was feeling a spot of resistance in the steering at a certain point on hard left turns. I practiced this repeatedly for a time and then sat checking all the other things such as play to and fro and comparing the difference with the engine running (power steering) vs. the engine off etc.

Then, on such a lovely, peaceful California day I sort of decided to head home. However when I hit the street I had this funny feeling that Hmmmmm, "What if something is really wrong?....what if there is a suddenly broken steering joint or U-joint in some mysterious spot etc. etc. I quickly rewound the mental tapes to some 40 years ago when I had been driving a 48 ford hot-rod that the steering had gone out on and I had almost killed myself watching the car steer itself down to a dead stop against a tree and a fence. I survived that incident Ok, but the memory of speeding along with no control of the car was suddenly very fresh in my mind.

So I drove slowly to the right side of the road, telling myself that I was doing it for the car (wouldn't it be horrible to scratch this gorgeous toy) rather than fearing for my own invaluable and aged carcass. So, I tooled along like an electric car for the elderly with the wind blowing ever so gently through the fully open windows and the lovely sun pouring through the open sun-roof. Then my very own neighbor who had a new BMW 323 black convertible drove by with her dark hair blowing in the breeze as she sped by with a huge cheerleader grin and long attractive outstretched arm dangling with jewelry and hollered "Hey Slowpoke" get a good car!!! continuing our unlimited banter over the better car each time we wash or put them to bed under their covers at night. (who needs children).

Then I finished my drive home and slowly crept up the driveway into central position, always the best spot for Calypso as I so tenderly refer to V12 Coup. Then my Dad who just turned 81 came out and witnessed the merciless teasing I was receiving from my neighbor for going so slow and he said after "Kurt, what's the problem?" as he has a way of knowing that I have a problem sometimes even before I do.

I considered the situation and I told him that I was noticing the lopsided wheel and then just earlier a resistance in the turn going left. The old Stanley Steamer, Studebaker, Model T, Buick, Chrysler, 32 ford, 34 ford and 36 & 37 Ford man, father & backyard mechanic who taught me everything I know said "Why don't you show me what your talking about". So, I did.

Then Dad rolled up his retired school administrator sleeves and exposed his world war II Navy Tattoos that have become somehow a most respectful and tender reminder of the years gone by as well as those here now and he told me to open the hood and watch as he continuously turned the wheel to the resistance spot and back again and again. So we did that, father and son as we have done for some 50 some years before through car after car and again just as always Stan (dad) said slowly, "well, I think I have found your problem." I stood up and looked at him and he smiled that famous lazy old smile that has charmed people for years He then slowly spun the wheel around and around without any resistance or any tires moving at all right before my eyes!

I had no choice but to smile back, and chuckle as my mind tried in vain to catch up somehow to the stark and dangerous reality of this situation as it slowly at first and then like a block of cement hit my perceptive reception area and left a dent that almost knocked me off my feet. I was immediately in a fraction of a second remembering the recent cars whizzing by in the opposite direction minutes ago and the last time (only a couple of weeks ago) that the wheel had been removed and worked on by the local dealer here in Sacramento.

A chill just sort of worked it's way up my spine all the way into the base of my skull and seemed to be taunting me in a kind of childlike rhyme like we all used to spit out at each other when we had just caused each other to crash our bikes or fall backward over a buddy bent over behind us.

I was immediately mad, frustrated, amazed, angry and then amazingly and incredibly thankful that I was standing here alive and that my lovely toy was not bent around a tree or trying to become part of the inner working of a local Japanese car coming from the other direction just earlier today. In other words, My steering wheel had come disconnected somehow just under the dash where it somehow connects to the steering shaft.

I slowly locked up the car and took the food into the house. I poured Dad and mom and myself a small glass of wine and then I immediately came into the computer room here (used to be Dads office) and sat down without a moments hesitation and wrote this little ditty to all you fellow E31, 850 owners who should know that if your steering wheel ever takes a sudden leap toward one direction or the other, regardless of how well it seems to work, it is obviously a very dangerous situation and could end up killing you if you don't check it out.

I am going to go out now and eat dinner with mom and dad, my two best friends in this world and be very thankful that I am alive and able to spend this time in their company as well as write this news to all of you here.

I suppose that after dinner I will want to determine exactly what the steering shaft is composed of under the dash and how exactly the dealer could have allowed his last repair for noise when the wheel turns to end up with my wheel turning freely in my hand with no control of the car. Man, life certainly is an interesting process. Kurt.

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Well, I am more than a little embarrassed. Sometimes it is easy to go "off the handle" as they used to say, or "going on and on" etc. When I finally decided that it wouldn't hurt anything if I just took out the lower trim panels and lower dash panels to take a look under. So I did exactly that, without touching the steering wheel or the battery.

It took all of about 15 minutes. Easy to figure out, undo the plastic screws, remove the false cap on the hood release unscrew it, off it comes, off comes the hard plastic kick panel trim. Then remove the upper/under the dash black cover (4 plastic screws)(one mysterious electrical switch no one told me about fastened to black under/cover, I will have to find out what it goes to later) off it comes.

Remove the upholstery-colored trim piece in a U shape going around from door to consul just under the dash instrument and steering column area by removing two phillips head screws and pulling straight out to bring other screws out of press plugs in the metal backing of the inner/under dash.

Then looking under I found a piece of hard black plastic heater pipe that had a phillips screw, I unscrewed it, then jockey the long hard piece back and forth till it pops loose and then "Presto", lying on my back I can see the whole steering assembly all the way from just behind the back of the steering wheel down to where it disappears into the engine compartment.

What I found surprised me. It seems that Justin was right after-all when he said he had to replace a coupling in his steering shaft assembly.

If you remember I had been told by several BMW mechanics (professional) that there was virtually nothing that could break under there, "If it was the same as most other BMWs". Well, either they were wrong, or the 850 is different from most other BMWs, because there is.

It shows in the steering wheel/column diagram of parts etc. A rubber coupling #17 that is a U-joint of sorts that connects on one end to the "lower (underdash)shaft assembly" #15, and on the other end to the Flange #16,(which is a small metal piece with splines fitting over the steering wheel shaft as it comes down from the area behind the steering wheel and is held firm not to be moving by a bolt that tightens it. This rubber coupling can definitely break, tear, rip, wear out and come apart leaving you no steering.

Anyway, this coupling 17# is mounted to the flange #16 on one end and to the lower shaft #15 that heads down toward the eng compartment on the other side of the coupling.

So the coupling #17 is a very thin 1/4 thick round piece of rubber with fiber insides that has 4 holes in it. Two bolts from the flange #16 go into two of the holes with nuts to hold them tight from one direction (just under steering wheel) and the other two holes are for two bolts that come from the lower shaft assembly #15 that heads down for the eng compartment.

So this round piece of rubber with 4 holes in it, with 4 bolts pushed through and held by 4 nuts is obviously a direct U-joint type of link in the steering wheel/column (under dash) steering shaft assembly.

If this rubber gets old and tired and decides that it doesn't want to hold together any more....for whatever reason....then it simply rips and tears and comes apart....as it has done on my car.

It is not the Dealers fault, unless the service technician purposely cut it or ripped it or ignored normal wear and tear, or didn't notice it. But, I hate to think that any of those possibilities are feasible, I would hate to go through my daily life thinking that. So I will choose to think that it just happened one day as it just finally after 9 years decided to wear out and come apart!

The main message here is that every one of you with an 850 has the same weak rubber link in your steering (under-dash)shaft assembly. Unless it was changed somehow after 1991. Should be easy enough to check out with the parts books.

Anyway, it looks simple to replace. Remove 4 nuts from 4 bolts and slowly remove the old torn shredded rubber piece and put in a new strong piece and place it carefully over the bolts of the lower shaft #15 on one end and then over/into the bolts of the flange #16 and replace the nuts to the proper torque and you are done and you have good steering for another 5 to 10 yrs.

However, it is such an easy thing to check, it would seem a good idea to check it out when you have the lower dash trim pieces off for any other repairs or work such as speakers, heater stuff, electrical etc. etc. With those lower pieces off all you have to do is lay on your back, take a light that shines up and reach up and check it with your hand or watch it as someone turns the wheel (turn it yourself-eng running power steering) etc.

If the rubber shows cracks or tears or looks dry and brittle or the bolts seem to be wearing oblong holes in the rubber, then replace it.

Amazing revelation to me today. Now all I have to do is find a new rubber coupling piece on late Saturday or Sunday.....and I got it made!!

I hope this information helps anyone who is interested and those in the future who begin to notice strange happenings in their steering especially when everythiing under the car, steering arms, joints, gears linkage etc. all look fine. Then it would be a good idea to check this very easy to find rubber coupling under the dash.

Have a good weekend gentlemen and thanks again to all who helped. Kurt

Gentleman all, especially to you Lez, Mark and Justin and anyone I may have forgotten, I want to say a genuine thanks.

It is becoming clear to me that the BMW 850 V-12 is nothing more mysterious than a car. A car is a car is a car. Figure it out and fix it, just like all the others in my life. I guess that I have just gotten so far away from repairs in the last 5 years that I didn't realize. I've worked all my life on cars, rebuilding, racing, restoring for 40 some years and I guess I just got tired or bored with it 5 years ago. But, it's amazing how easy it is, how you don't forget all those years of experience and how good the tools still work. Using Dads in this case, the same tools that he used since the 30s through the 70s till he stopped working on them. Funny. Anyway, Thanks again, Now I'm off to look for parts. I know, I know, Good luck until Monday!!

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I have finally finished the Saga and important scenario of the life-saving and necessary steering that all our cars share regardless of the year or model etc. Here is the information for all who like steering that works and who deem it necessary to know how to keep it that way.

First of all I cannot express enough the importance of finding an "Honest, Knowledgeable, and Experienced mechanic that you can talk to easily!!!" I know, usually that is referred to as "The Impossible Dream"!

Most of you 850 or E31 owner/drivers do not work on your cars and therefore most of what is said on this board about mechanics is Greek. For that reason and to make it simple for those of us who do enjoy the grease of wrenching this job has turned out to be simple, as with most highly touted complex mechanical scenarios.

Steering linkage under the Dash:

- The one most important factor of the steering under the Dash is the adjustment of the big Nut surrounding your lower steering shaft just before it disappears through your inner firewall into the engine compartment. This big nut is referred to as a compression nut. This big nut, if improperly made too tight will stop the necessary sliding movement back and forth (in and out)(yes like sex) that is required to occur when you activate your electric steering wheel adjustment closer or father away from you or the dash. If someone, (you or mechanic) tighten this nut to the point that stops the in and out sliding of the splined shaft, you will effectively cause tremendous pressure and distortion to occur to the Rubber Dampener Coupling that is located further up the shaft, and this Rubber Coupling will then begin a very rapid deterioration forcing its retaining nuts to embed themselves into the rubber and then effectively cause a rip in the Rubber Coupling that will cause total loss of your steering. This process takes anywhere from a week to a month or two depending upon how often you drive the car and how curvy your road. The more you turn the more you lose.

- When the lower Nut is tightened so that the splined shaft cannot go in and out with movement of the electric column control, then the Rubber coupling is forced to stretch beyond it's limitations, especially if it's adjusted tight in the down (close to the dash) position and then the control is activated to bring the wheel closer to the driver. In that case the distortion becomes immense and intolerable to the Rubber coupling.

- Should one ever desire to check this out, you can easily remove the under the dash trim pieces and take a look. This shaft and all it's components are easy to remove and replace as long as the big nut is able to be loosened. In most cases this is no problem. If it cannot be loosened then you must remove it from the car and put it in a vice and make it loose! (rare case, but this is what I just had to do. Someone had tightened mine so tight it would barely come loose only after a heat torch made it very hot!! I will always wonder who did this and why??? It did just come out of the dealers shop 3 weeks earlier for steering column work, what can I say!)

- Anyway, if the Nut will come loose usually by putting a big wrench on it and turning with someone else helping you turn the steering wheel in the opposite direction. After the Nut is loose you would then remove the four retaining nuts, two on either side of the Rubber Coupling that is located between the Flange (two mounting bolts)and the upper end of the lower steering shaft (the other two mounting bolts)and then you loosen the nut enough so that the main shaft with nut can be pushed inward toward the engine to create enough room to take apart and take out the old Rubber Coupling and insert the new one.

- The Rubber Coupling does not come with the Nuts and the Wavy (spring) washers that are necessary to do the job properly. You should use new ones of stainless steel strength, The wavy washers must be a size almost exactly 8mm ID.(inside diameter) X 15mm OD.(outside diameter) Both sizes are critical. The ID. must be 8mm to allow the bolt to pass through and the OD. must be no bigger as then it will begin to impede the proper movement of your required steering when turning. It is *imperative* that the Rubber Coupling (with steel cylinders positioned inside each hole at the factory) is placed in the mounting bolts slowly and carefully making sure that they are gently urged a little at a time onto each bolt a little at a time until the Rubber Coupling has fully inserted all four bolts all the way into all holes before attaching any washers and nuts.

- At this point you will want to attach the Washer first over the mounting bolt sticking through the Rubber Coupling and then the Nut making it only finger tight. You will only be able to do one bolt at a time, that bolt which you can see which will be the closest nut to you, and then you will want to activate the power steering for a few moments to easily turn the wheel to the next nut to begin putting on the washer first, then the nut, then finger tightening and so on till they are all tightened only by fingers. Then once finger tightened you will want to wrench (13mm) tighten each one to a torque spec of 16 to 20 lbs. That means using your hands with the 13 mm wrench to make them very tight, but nowhere near your maximum hand tightening power which could be 50 to 75 lb torque that's not necessary! you just want good and normal tight! . You will use the same method of turning the wheel via power steering from nut to nut.

- Once the coupling is properly attached and retained by wavy washers and self-locking nuts properly tightened, you will want to activate your electric steering column control and watch the column go in and out and see if the shaft down just below the nut (passing through the fire-wall into the eng compartment) is sliding in and out of the big nut (yes, like sex). If it is not sliding then the nut is too tight. If it is sliding then you need to adjust it. The best method I have found to use is to simply have a big wrench of the proper size and to tighten the Nut to the point just where it stops the movement in and out of the splined shaft. Then immediately turn the big nut back one full turn so that the shaft will easily move in and out of the big Nut. Also make sure that the shaft is properly greased in the grooves with a good bearing grease. "Properly" means just enough grease to fill the little groves, not a big mess all over everything.

- At this point it is always a good idea to raise the hood and to check the nut located on the steering gear universal joint to make sure that (hopefully it is there) and that it is tight, holding the other end of the splined shaft firmly to the steering gear. The spline is located just inside the firewall in the engine compartment where it comes through from inside the under dash where you have just been working and then down to the steering gear where you will see the universal joint with just one bolt and nut holding it tight.

At the moment, typing fast and trying to get this done as I am late (as usual) I may have overlooked something. However, if any of you have any questions later please let me know and if you know of any better method of doing this job in any phase I would sure appreciate knowing of it. There is always room for improvement when it comes to mechanics and proper methods.

Thanks for listening Ladies and Gentleman, I hope this information is of help to someone in the future.

Kurt Grayson

Paul, I posted a lengthy description of the repair about six months ago.
I've also sent out scanned pages of the seat removal process to several list members.

There is a single motor under the front edge of the seat responsible for raising and lowering the seat cushion using two scissor-jacks located on both sides.
When one cable fails, only one jack works and the seat rises unevenly.

The jack gearboxes are located at the back of the seat, and two cables are used to transmit power from the motor to the gearboxes.
The drive cable consists of what looks like a tightly-coiled piano wire inside a protective outer jacket.

For some silly reason, BMW's cables fail due to the inner drive wire shortening inside the fixed outside jacket.
The solution is either shorten the outer jacket (my recommendation), or insert a short length of coat hanger into the end of the motor and reinsert the failed cable (untested, but I've been assured this works).

It's possible to fix the seat in the car, but I prefer to remove it by simply unscrewing the six big T-55 Torx bolts holding the seat rails to the floor and disconnecting the electrical plugs.
Once the seat is removed, simply loosen the failing cable from the motor (two small bolts and a retaining clip), remove the cable and the inner drive wire, carefully work the end fitting loose (hardest part), and strip back about 2 mm of cable using a hacksaw.
Attach the end fitting, reinsert the drive wire, and attach everything to the motor.

Replacing the cable completely is time-consuming since it involves removing a good deal of parts at the rear of the seat.
Furthermore, you'll soon have the same failure as the new cable shortens and disconnects itself from the drive motor.
The shortening procedure is the preferred repair method.

If the dealer understands the problem and will fix it for only $60.00, I'd strongly recommend letting them do it.

Fling, Mark F.

Thanks to Mark Fling's excellent description, I was able to fix my driver's side seat at home this weekend in about and hour.

I did first look at the pass side to see how the San Diego dealer did it.

As Mark wrote, first take the map pocket valence off by unscrewing the two screws after you carefully take the leather pocket off by prying out the five (one on each side by the screws and three on bottom) plastic inserting/gripping buttons.
(the dealer broke one of mine on the pass side so it was super glued and put back).

You will then see the motor with two 'Bowden' cables coming out of each side.
You can determine which one is the offending cable by noticing which side of the seat comes up - that side is the good side/it's working.

By the way, I decided not to take the seat out - it is possible to do it with the seat in place esp.
if you are gone work on the cable that is slightly longer (outer one on my driver's seat) - you will see what I mean when/if you open it up.

The shorter side cable is also attached to electrical cables with a tie so you would have to snap it off before working on the cable.
I didn't have to cause the longer side is without any attachments.

Take the cable out of the motor by undoing one of the two screws on the plate - no need to do both since it will drop off and let the cable out.
One less hassle when you are putting it back.

Pull the greasy cable out and leave where it won't take the grease off -

I then took my Dremel rotary tool and cut the cable sheath/housing about 1 1/2 inch from the end then cut another 1/4 inch or less on which ever side - doesn't matter.

I bought a 5/16th" fuel hose (79cents/foot) and cut about 1 1/2 inch of it and slipped the two sheath into it and clamped them on both side with appropriate size hose clamps ($1.39).
I then put the cable back in - there is a plastic guide ring that may come out with it when you pull the cable out so make sure you put that back in as well...and reattached it back into
the motor and voila, it worked - seat went up and down well with no problem!

EXCEPT, now the seat wouldn't go back and forth - !!!
S so i called Mark in mild panic, who thought I probably had the seat still in torqued/twisted position
I checked the seats visually and sure enough, my seats were way too close to the center console and just not mechanically/physically able to move thru it's range.

With the cable out, i adjusted the seat 'til it looked about levelled/straight and put the cable back in and this time, the back/forth movement was without any catch - nice and smooth!

So, there you have it - it is a very easy fix and if you are not too big to work in that cramped spot, it can be done without taking the seat out!

Again, thanks to Mark.

James Rho

Did the standard US 1991 850i model come with the alarm receiver installed yet no remote sender unit? I'd like to add the factory remote lock/unlock feature. What's interesting is that the owner's manual shows a procedure for re-orienting a new infra-red key sending unit by aligning it with what appears to be the standard apparatus in the center console (the red light that blinks when alarm is armed) present in all 1991 850s. The dealer's here in SF are clueless and suggest aftermarket alarm systems are the only option. Has anyone been down this path before? Can I just buy the remote sender unit and orient as described in the manual?

[Sounds like a job for Mr. Fling's massive technical library. I too own a 1991 850i and by the time I read the part of the owner's manual describing the remote control device I had lost touch with the original owner of my car. So I don't know if he had the remote control and failed to give it to me or if he never had it in the first place. I also seem to recall some discussion (can't recall the source) about how some E31s have an infrared remote control system, while some have a remote control system utilizing radio (like most modern aftermarket systems). IIRC, the early E31s had the infrared remote control system and at some point the system was modified to radio control. On my car, there is what appears to be a infrared receiver on the interior mirror that "looks" out through the windshield. It sure would be handy to have the remote locking function enabled. If it's just a question of purchasing the remote and aligning it per the owner's manual it doesn't seem that hard to do. Can anybody provide a BMW part number for the remote control? PMB]

Gregory Kovecses

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When we bought our 850 we were wondering the same thing (since both of our 75s have this remote and the manual for the 850 shows it). We went out and bought the remote (which is the same as the 750). Guess what...it doesn't work. I posted a note on the BMW-digest list over a year ago trying to find out information on this. I got this reply:

"The E31 in the US never had the IR remote. Something about the windshield angles would cause it not to work well. They did have the optional Alpine keyless entry, but it is no longer available from BMW."

This is probably why they switched to the standard radio frequency remote that most cars have. Even the infrared ones on our 750s are finicky depending on where you are standing. Hope this helps; if you find anything to the contrary, please let me know.

[Hmm. Yet another E31 mystery. Might it be possible to purchase the remote from a European source? Or maybe it would be possible to use one of those "learning remotes" that you can buy for your home entertainment system? I don't have any idea how they work, but I do know they operate in the infrared band. Perhaps one of our technically-learned members could weigh in here. PMB]

John Rather

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With respect to Mr Rather's previous post, I am an owner of a Euro-spec 850. I do not have a remote control to my car. Is anyone aware of how I would go about obtaining one, short of contacting BMW-AG?

Gregory Long

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"The E31 in the US never had the IR remote. Something about the windshield angles would cause it not to work well.

I have an infrared remote for my CSi. It works perfectly, including closing and opening all windows and sunroof. What is the difference between my windshield and the U.S. windshield? Probably what you see through it :-).

[Yeah, we see giant signs advertising gasoline for $1.50 USD per gallon! Seriously though, if it works on Mr. Holm's car, why can't I get it to work on my car?]

There are three things to consider; firstly: - Does your car have an IR receiver at all? (it's supposed to be in the center console), secondly: - Each IR transmitter (built into the keygrip) is unique for each car. If you take another one, it is not supposed to work, for obvious reasons. Third point is that newer cars (-95+) have an advanced immobilizer system where the keygrip also contains the transponder for the security system. This is also an individually coded device.

[On my 1991 850i, I have a rectangular reddish plastic "window" on the center console. I presume this is used as per the owner's manual to initialize the remote control so that it only works on my particular car. I also have a circular reddish plastic "window" on the front side of the mirror, facing out with a "view" through the windshield. I assume this is the device that would receive the IR signal transmitted by the remote control.]

BTW, the European 7-series IR remote also controls the trunk lid.

Your dealer (or BMWNA) should be able to determine whether you could buy an IR remote control for your alarm and central locking system for your specific car. Price for an Ersatz-transmitter (keygrip type) is around USD 75 at BMW AG in Germany, including programming.

[By "Erstaz," I assume Mr. Holm means what we would call a "replacement" in American English.]

I remember a discussion on a list where the topic was that BMW had to drop the remote closing of windows etc on all American cars, since they were afraid of getting sued. It was allegedly so that the (IR?) remote worked from a longer distance than what could be allowed in the U.S. This explanation sounds plausible to me.

[I read the same thing. The problem was that you could roll up the windows from so far away that you might not notice somebody was in the way. BMW trusts me with a car that will go 150 miles an hour, but they're worried I'm going to hurt somebody with my power windows?!? Yet another example of the plaintiff's bar running the country. Perhaps this fear of liability is the reason it is apparently difficult to obtain the IR remote here in the USA. PMB]

Magnus Holm

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I have a 92 E31 which came with a radio controlled remote. The signal strength is weak and I have long since abandoned its use. Supposedly, the 91 had a stronger signal or was IR. Accordingly to the dealer I originally purchased from, it was modified because of an accident involving a child. I don't know if this was BS. One cool thing about the original remote however, was supposedly that it activated the circuit that closes all windows and the sunroof, just like holding the key in lock position for 10 seconds.

MMROTHKOPF

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I actually tried to buy the remote key. In fact the dealer listed the part number for it. When it came in, I could not get it to work. The initialized on the console seemed to work as described in the manual. Unfortunately, the infrared signal did not work. This is something I would love to see working on my 91. I wonder if the Euro parts could still be sourced?

Stephen Spears

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I can only offer limited information, but when I bought my E31, I thought it was ludicrous that the car did not have remote entry. Upon digging in the euro parts fiche, it appears that the infrared receivers are in the door handles-they (the handles) are specifically listed as different for the remote system. There is also some additional electronics involved. The handles alone are about $700 each as I recall, so I gave it up as not being cost effective. An aftermarket radio frequency unit would probably work, since the lock/unlock mode can be triggered by grounding one side or the other of the circuit through a resistor.

Phil Saitta

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When I purchased my '92 850I, I asked the original owner about the red light in the center next to the stick shift.

He mentioned that the manual walks through a procedure to program a remote control etc.

When he asked his salesman about the option to get this remote-open feature, he was told that they recommend an Alpine radio-type alarm system that protects the car as well. The owner decided to get a Clifford alarm ($1500!!) installed instead.

I would also be curious to know why BMW opted not to provide the remotes with the 850i when purchased new. It seems odd to have the LED light and the receiver, but to not recommend using this feature (which appears to be standard on just about every BMW these days.) I know that to pay $86,000 USD for the 850I in 1992, you should at very least have this option as a standard feature.

By the way: I really love my alarm system. It has more features than I'll ever use. The one I really enjoy is when you hit the button to lock the vehicle, it automatically closes any open window and the sunroof. There is another button that you can hold down to open all the windows and the sunroof while unlocking the vehicle. It's nice to park the car with any combination of windows/sunroof open and just hit the "arm" button and walk away.

My recommendation would be to investigate the alarm system options with radio-type transmitters/receivers. Be sure you get a roving-code type of alarm system as well.

Sean Drury

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I had no problem buying the switchblade remote from a dealer through the net. I can dig up the part numbers and the contact if you need them. The remote costs about 130 USD with a 25% discount included. I bought one and subsequently returned it when I couldn't get it to work. Go figure. Interesting thread.

JR Hope

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In the never ending search for the Holly Grail, i.e., remote locking for early E31s, I refer you to the posting by Derek on the BMW 8 Series Forum referring to a Eurospec control unit that allows him to use the two-button key you can buy from BMW to lock, unlock, and operate the windows and sunroof. Might this be what we have been looking for?

Gentlemen: Here is what Derek had to say: I got my new key today - it's 2 button and it didn't work so they replaced the alarm control unit. I was lucky, the new control unit is a Eurospec so the remote key now does everything the manual one does. Opens/closes windows and sunroof remotely. If you have to replace the control unit you might try to get PN 65-75-8-368-680 DWA AL. Cost up here in Canada was $411. For those of you who have recently joined us, you should know that BMW has purposely disabled the remote control functions on early E31s (the ones with the infrared remote controls) sold in the United States. So even though you might purchase the two-button remote control, and even though you might initialize it as directed in your owner's manual, it won't work. Evidence is anecdotal, but it appears that the remote control as designed had a beyond visual range. In other words, it was possible to send commands to the car from a distance great enough that you would be unable to see the car. Evidently, the wimpy-ass lawyers at BMW became worried that somebody might use the remote control to close an open window when it was obstructed by a person. So they did something to the car's electronics such that it either won't receive (or won't act upon) signals from the remote control. Derek's experience certainly seems to suggest that the difference between an E31 with remote control capability and one without lies in the alarm control unit. But I caution that it's at least possible that the difference lies elsewhere in the E31's incredibly complicated electrical system and Derek just had a bad alarm control unit in his car. Moreover, even if we assume for argument's sake that the alarm control unit *does* control the remote control capability, we have the problem of acquiring a Eurospec part here in North America. As somebody who worships at the altar of stock, I have no idea how difficult that would be. Finally, I have no idea how expensive it would be to install the alarm control unit. All in all, this tidbit is certainly intriguing. I think it cries out for one of our intrepid DYI types to go where no E31 owner has gone before and to swap out his alarm control unit for a Eurospec unit and report back whether it enables the remote control functions. PMB

Bert Smith

"For the newcomers, OBC stands for On Board Computer."
And as everybody who owns an E31 knows, some of the pixels in the OBC's display eventually go dead.
The cause is a bad connection inside the OBC that permits dirt and moisture to creep in.
In theory, it is possible to remove the OBC and then clean the connection.
The more expensive fix is to replace the entire OBC, which sells for about $250.
If you are mechanically adept, you can remove and replace the OBC yourself.

1) Remove the vent grill directly above the console. There are two upper and two lower tabs that need to be depressed in removing the grill. Make sure to slide the unit to the right as you pull up because the grill piece is locked behind its neighboring part. Put the vent on top of the dash. (I put a cloth down on the dash first, the air vents are a little dusty.)

2) Slide a clean putty knife between the bottom of the OBC and the dash face plate. This ensures that the catch mechanism for the OBC is depressed. The catch mechanism on the bottom almost runs the full length of the unit.

3) Underneath the removed vent you will find a sheet of black plastic held in place by a small Phillips screw on the left side of the opening. You don't need to remove this sheeting. You can maneuver your hand around the plastic sheeting on either side to gain access to the back of the OBC unit.

4) Gently push the OBC out on both side till you fell the unit stopped against it's latching mechanisms. Using another putty knife, or a small flathead screw driver, depress the latch mechanisms. There are three on the top side evenly placed along the top. The unit should easily slide out at this point.

5) If you are just replacing the unit, simply unlatch, reattach and slide the new unit into place with a click.

--------------------------------------------------------------------------------

The OBC is probably one of the most notoriously failing electronic items on BMWs.

It's a rather stupid construction, as it relies solely on a tiny plastic piece to hold a 200-or-so-pole connector in place. We´re lucky not to be in outer space with a ship of that build quality.

I eventually got around to fixing my own OBC. I must warn you, this is one serious "can of worms", they really built the OBC to be unserviceable - except for changing the bulbs, which can be done from the outside. I haven't figured out the "definitive DIY fix" yet, but there is a simple method, the "QD Solution" to the pixel flicker.

Firstly, you need to determine whether you have a "Siemens" or a "Borg"
OBC. The factory part # sticker will tell you this. The Siemens is basically self-explanatory once you figure out how it's opened, the Borg is a real PITA (just like its Star Trek counterpart and needs extra caution when opening.

The LCD is connected via a flexible lead (etched ribbon strip). One end is sealed into the LCD, the other is glued onto the printed circuit board (PCB) and is held in place by means of a rubber-like padding under the plastic lamp reflector assembly. The problem area is, of course, where the flexible cable meets the PCB. Dirt "creeps" in via the air travelling through the front panel (you can see the black stuff inside the white plastic), and eventually gets under the ribbon-cable. Smoke is of course detrimental to a setup like this.

To clean it properly, one wants to remove the ribbon strip, but after that you really have some trouble putting it back in place as the glue is a one-time-only type, and there is some sort of heat-molded graphite stuff connecting each of the poles. I still haven't figured out how to fix this, so don't try to remove the cable.

What you do instead, is to spray contact cleaner from the back, so that the fluid goes between the PCB and the ribbon strip. I even tried spraying directly from the front, in the lower part of the LCD, and this actually worked on my friend's -95 328iA cabrio (also equipped with a "Borg" OBC). So, that should be tried first before the procedure below.

To clean "Borg" brand OBC from inside (the Siemens is similar but needs no further explanation to open):

1. Ignition off. Lights off. Take out the OBC by first removing your car stereo (disconnecting it is not necessary if it has original cabling) then pressing the plastic flap under the OBC inwards. The plastic flap covers 2/3 of the OBC bottom width and has two hinges at each end. Be careful if you have the wooden center console, the small strip of wood between the stereo and the OBC cracks easily. The OBC pops out. Remove the connector (one on Borg, but I've seen Siemens models with two connectors). Connector comes off by pressing the striped plastic "button" and folding the plastic lever over it. It's a rather crappy plastic connector, so be careful.

2. Make sure you have a reasonably anti-static work surface and clothes.

3. Disassemble the OBC: press the four black plastic hinges inwards, loosening the corners one at a time. The hinges are located at top and bottom rear corners. The back piece will now come off.

4. Locate the two black "fork type" plastic hinges holding the PCB in place, they are equidistant from the center of the PCB. (I think that "PCB" stands for printed circuit board. PMB) The plastic hinges are pressed together using a small plier or similar, allowing them to slip through the rectangular hole in the PCB. There are two white plastic hinges on the outer sides of the OBC holding the whole lamp assembly, these need to be depressed a little to allow the PCBs and LCD to come out of the box. It takes a little fiddling and some force to get it all out, but it can be done. Be careful not to apply too much pressure on the LCD itself, as it is made of glass. The LCD holder is a frame that runs all around the LCD, this has a tendency to get stuck on the way out. More fiddling required, and a good level of tolerance.

5. Now the white connection strip between the backlight lamp assembly and the LCD should be visible.

Do NOT attempt to remove the lamp assembly, it is soldered and holds the flexible cable in place. Clean the connection pads on the flexible cable with spray-on cleaner. Suitable cleaning agent is an alcohol or freon based spray, or any good quality contact cleaning spray without oil. Do NOT use 5-56 or similar greasy products, or graphite spray. Do NOT attempt to loose the flexible strip from the PCB edge connector (it won't go back that easily, as I've found out...).

7. Clean the LCD front while you're at it (you may find collected grime at the edges).

8. Reassemble in reverse order. Make sure the flexible cabling is not damaged, and that the LCD is in no way bent.

Apparently I did not recall correctly, and gave you the wrong sequence for the OBC test.

The proper sequence is : 1000 & 10 simultaneously, then 1, then SET/RES. The ignition switch must be in the on position.

You can also run some other test (all of them very simple) by substituting other numbers for the "1" in Mr. Lang's procedure. PMB

Jlang575

--------------------------------------------------------------------------------

I wanted to share a quick and painless way to remove and replace your OBC display. I just completed mine in roughly 15 minutes. I am not sure if this method has been posted in the past, but I wanted to share it with everyone.

[For the newcomers, OBC stands for On Board Computer. And as everybody who owns an E31 knows, some of the pixels in the OBC's display eventually go dead. The cause is a bad connection inside the OBC that permits dirt and moisture to creep in. In theory, it is possible to remove the OBC and then clean the connection. (Mr. Holm is the resident expert on this procedure.) The more expensive fix is to replace the entire OBC, which sells for about $250. If you are mechanically adept, you can remove and replace the OBC yourself.]

1) Remove the vent grill directly above the console. There are two upper and two lower tabs that need to be depressed in removing the grill. Make sure to slide the unit to the right as you pull up because the grill piece is locked behind its neighboring part. Put the vent on top of the dash. (I put a cloth down on the dash first, the air vents are a little dusty.)

2) Slide a clean putty knife between the bottom of the OBC and the dash face plate. This ensures that the catch mechanism for the OBC is depressed. The catch mechanism on the bottom almost runs the full length of the unit.

3) Underneath the removed vent you will find a sheet of black plastic held in place by a small Phillips screw on the left side of the opening. You don't need to remove this sheeting. You can maneuver your hand around the plastic sheeting on either side to gain access to the back of the OBC unit.

4) Gently push the OBC out on both side till you fell the unit stopped against it's latching mechanisms. Using another putty knife, or a small flathead screw driver, depress the latch mechanisms. There are three on the top side evenly placed along the top. The unit should easily slide out at this point.

5) If you are just replacing the unit, simply unlatch, reattach and slide the new unit into place with a click.

Stephen Spears

--------------------------------------------------------------------------------

>I have a problem with the display of my onboard computer.<

Don't we all... The OBC is probably one of the most notoriously failing electronic items on BMWs.

It's a rather stupid construction, as it relies solely on a tiny plastic piece to hold a 200-or-so-pole connector in place. We´re lucky not to be in outer space with a ship of that build quality.

I eventually got around to fixing my own OBC. I must warn you, this is one serious "can of worms", they really built the OBC to be unserviceable - except for changing the bulbs, which can be done from the outside. I haven't figured out the "definitive DIY fix" yet, but there is a simple method, the "QD Solution" to the pixel flicker.

Firstly, you need to determine whether you have a "Siemens" or a "Borg" OBC. The factory part # sticker will tell you this. The Siemens is basically self-explanatory once you figure out how it's opened, the Borg is a real PITA (just like its Star Trek counterpart and needs extra caution when opening.

The LCD is connected via a flexible lead (etched ribbon strip). One end is sealed into the LCD, the other is glued onto the printed circuit board (PCB) and is held in place by means of a rubber-like padding under the plastic lamp reflector assembly. The problem area is, of course, where the flexible cable meets the PCB. Dirt "creeps" in via the air travelling through the front panel (you can see the black stuff inside the white plastic), and eventually gets under the ribbon-cable. Smoke is of course detrimental to a setup like this.

To clean it properly, one wants to remove the ribbon strip, but after that you really have some trouble putting it back in place as the glue is a one-time-only type, and there is some sort of heat-molded graphite stuff connecting each of the poles. I still haven't figured out how to fix this, so don't try to remove the cable.

What you do instead, is to spray contact cleaner from the back, so that the fluid goes between the PCB and the ribbon strip. I even tried spraying directly from the front, in the lower part of the LCD, and this actually worked on my friend's -95 328iA cabrio (also equipped with a "Borg" OBC). So, that should be tried first before the procedure below.

>Hmm. Does this means it might be possible to leave the OBC installed and >just spray contact cleaner into some "crevice" that will permit it to flow >to the spot where the dirt builds up and shorts out the pixels? If so, >that's a revolutionary fix for a niggling problem that affects all E31s to >one degree or another. Anybody else try this? PMB

To clean "Borg" brand OBC from inside (the Siemens is similar but needs no further explanation to open):

1. Ignition off. Lights off. Take out the OBC by first removing your car stereo (disconnecting it is not necessary if it has original cabling) then pressing the plastic flap under the OBC inwards. The plastic flap covers 2/3 of the OBC bottom width and has two hinges at each end. Be careful if you have the wooden center console, the small strip of wood between the stereo and the OBC cracks easily. The OBC pops out. Remove the connector (one on Borg, but I've seen Siemens models with two connectors). Connector comes off by pressing the striped plastic "button" and folding the plastic lever over it. It's a rather crappy plastic connector, so be careful.

2. Make sure you have a reasonably anti-static work surface and clothes.

3. Disassemble the OBC: press the four black plastic hinges inwards, loosening the corners one at a time. The hinges are located at top and bottom rear corners. The back piece will now come off.

4. Locate the two black "fork type" plastic hinges holding the PCB in place, they are equidistant from the center of the PCB. (I think that "PCB" stands for printed circuit board. PMB) The plastic hinges are pressed together using a small plier or similar, allowing them to slip through the rectangular hole in the PCB. There are two white plastic hinges on the outer sides of the OBC holding the whole lamp assembly, these need to be depressed a little to allow the PCBs and LCD to come out of the box. It takes a little fiddling and some force to get it all out, but it can be done. Be careful not to apply too much pressure on the LCD itself, as it is made of glass. The LCD holder is a frame that runs all around the LCD, this has a tendency to get stuck on the way out. More fiddling required, and a good level of tolerance.

5. Now the white connection strip between the backlight lamp assembly and the LCD should be visible.

Do NOT attempt to remove the lamp assembly, it is soldered and holds the flexible cable in place. Clean the connection pads on the flexible cable with spray-on cleaner. Suitable cleaning agent is an alcohol or freon based spray, or any good quality contact cleaning spray without oil. Do NOT use 5-56 or similar greasy products, or graphite spray. Do NOT attempt to loose the flexible strip from the PCB edge connector (it won't go back that easily, as I've found out...).

7. Clean the LCD front while you're at it (you may find collected grime at the edges).

8. Reassemble in reverse order. Make sure the flexible cabling is not damaged, and that the LCD is in no way bent.

Now, I just need to figure out how to put my own OBC back together...

>This is, by far, the most comprehensive report to date in respect of >repairing the infamous dead pixel problem without replacing the >entire OBC. Definitely a SUPERB piece of work. Hats off to Mr. Holm >for being willing to experiment on his car and for being willing to >write it up for us. Of course, as Mr. Holm candidly notes, it is >not the last word. If anybody has additional information based upon >their own experience, please pass it along. PMB

Magnus Holm

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If a large section of your display is dim but not dark, perhaps it is just a bulb burned out. My pixels went dead in a random pattern. There is a test for the display. IIRC, you press the 1 and 100 button simultaneously, then press the set button, all pixels will illuminate. This help you tell if it is a pixel problem, bulb problem, or both.

>This is a good point. As Mr. Lang notes below, the pixels are >backlit by four bulbs inside the display portion of the OBC. They >do burn out and they can be replaced. So if you have a problem >where an entire "block" of pixels is dead of dimmed, you should >probably troubleshoot the bulbs.

About 20% of the pixels in my OBC are dead so tried to follow the repair instructions from the owners group. I have the Borg version, which is very difficult to disassemble, but I finally got it apart. The flexible ribbon wire is permanently attached to the display and is not removable without destroying it, so I was not able to repair it.

However I did find 2 of the 4 bulbs that illuminate the display where burned out.

The dealer had these in stock so I replaced them. (The display does not need to be disassembled to replace them, just removed from the dash.) Replacing the bulbs brightened my display and made it easier to read, but of course did not fix the dead pixels.

Jlang575

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>After my car was detailed the left side of the display >...showed a definite fade from almost off...to normal strength

- It's probably just a half-dead OBC display illumination lamp or a dirty connection to same, these bulbs sometimes just come and go. Please refer to the previous posts on how to exchange these bulbs, or mail me directly for copies of the directions, it's an EZ-DIY fix.

After a detailing involving using an "ozone generator", to take away smell or smoke residue, the LCDs can sometimes go berzerk for a period of time, or even die completely. In the latter case it's the LCD driver chips that are damaged by static electricity. This happened to my original BMW stereo's display.

My WAG solution to that is to use a piece of aluminum foil (grounded to car chassis) to cover the LCDs during electrostatic cleaning. This may sound a bit like a religious ceremony but should work well - "better safe than sorry".

Further to the latest OBC pixel surge, news here in Europe is that BMW now has a rotating scheme for the OBCs - send in your old one and you get a rebuilt one. Will check price here.

>This suggests to me that somebody in the BMW parts system in Europe >did exactly what Mr. Holm did, namely examining the OBC and >discovering the design flaw that allowed dirt and moisture to short >out the connector that drives the display. I further speculate that >somebody at BMW decided that it was wasteful to discard the entire >OBC just because the connector was partially shorted out. Finally, >I suspect that somebody at BMW has figured out a way to economically >repair the connectors and to return the OBCs to service. Hence the >imposition of a core charge pricing policy for replacement units. If >I could talk to this person, I would ask him whether the repair >fixes the design flaw, or whether it just cleans out the dirt and >moisture, thereby guaranteeing that the dead pixels will return. If >the former is the case, then it would seem that a rebuilt OBC, with >a new and improved connector design, would be superior to a "new" >OBC and the dead pixel problem could be cured once and for all by >the installation of a rebuilt unit.

Somebody in the U.S. might want to talk to their local BMW service rep as well to get the current U.S. price, after all if they can fix it at a nominal charge it is preferable over my hack mechanic fix. What, if anything, came out of the VFD-OBC project we discussed last fall?

Magnus Holm

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This is just a short story regarding a recent change of the on-board computer (OBC) in my 850. As some of you have seen, I posted earlier some questions regarding changing the OBC as a total of seven (!) columns of bits on my display were blown.

With a lot of help from Lez, I got the part number and copies of the repair manual for how to change this particular part. Last week I ordered the new OBC from my local BMW dealer and it all went in around 300 US dollars.

I also had some excellent descriptions from both from Mr. Spears and Mr. Holm (sent to me by PMB) on how to both change and clean the OBC, but I finally decided to go for the simple solution to buy a new unit.

I had two ways of getting into the back of the OBC to be able to push it out. Either I could remove the air vent above the center console or I could remove the radio located below the OBC. I had some people warning me from trying to go the radio way as it seems that would be fairly tricky. The radio is secured by two covered screws which I was told would not be hex-key screws. Maybe my car is different, but I managed to remove the screws and the radio with a hex-key in just one minute.

After removing the radio to the side to be able to get my hand into the location where the radio normally fits, it is very simple to press in the large, lower clip which holds the radio in place from the lower side. Once that is done, the OBC comes out, but then locks on three tabs on the upper side which you need to depress. Turns out that the dash is so flexible that it is simple to push the OBC slightly downwards to have these tabs release the OBC that then simply pops out.

At that time I simply disconnected the cable from the back, connected it to the new OBC and pushed it back in and screwed the radio back on. Doing it all very calmly and slowly, it just took me 8 minutes to get it done. I can now finally read what the damn computer tries to tell me I just hope it won't be just to deliver serious error messages.

Looking at the old and new computers, I was amazed about its construction. The whole back side is open in a lot of places with a lot of holes which allow you to see the cables and the chips inside the computer. Looking at where it all is located and how dusty it is in there, I really understand Mr. Holms description on dirt. I cleaned the interior as much as I could and for a while I even thought of covering these small holes, but as that maybe causes the OBC to overheat I simply didn't dare to do it. Some experts out there who know if this unit develops a lot of heat? It probably is not a good idea to cover those openings, but it is evident that there is where the problem is.

Finally a big thanks to Lez who always has time to answer questions and to the previous members who wrote so good descriptions of how to do this, that it made my life simpler today when I made the swap.

Federico Engler

--------------------------------------------------------------------------------

I've got the following problem concerning the OBC-display in my '93 850CSI and I'd be very pleased to receive some hints:

Sometimes and not regularly some of the pixels, but especially one or two rows aren't properly working.

I already read (if i correctly remember) that someone wrote about this to be a common and known problem of the E31's. Nevertheless i don't know if this problem can be easily fixed in a do-it-yourself manner or if i have to give it to my local dealer for repair (and if so - has the complete display to be changed or only the connectors/wiring ?). Since I'm not a technical expert in those concerns I'm really thankful for any reply. Thanks in advance !

>Ah, I see that due to the influx of new owners here it is time to >re-post the information from the archives regarding the irritating >problem of dead pixels in the on-board computer (OBC) display. Here >it is, gentlemen. PMB

Marc Gellert

--------------------------------------------------------------------------------

Apparently I did not recall correctly, and gave you the wrong sequence for the OBC test for dead pixels.

The proper sequence is : 1000 & 10 simultaneously, then 1, then SET/RES. The ignition switch must be in the on position.

>You can also run some other test (all of them very simple) by >substituting other numbers for the "1" in Mr. Lang's procedure. PMB

Jlang575

--------------------------------------------------------------------------------

From: Stephen_Spears@gelco.com

I wanted to share a quick and painless way to remove and replace your OBC display. I just completed mine in roughly 15 minutes. I am not sure if this method has been posted in the past, but I wanted to share it with everyone.

[For the newcomers, OBC stands for On Board Computer. And as everybody who owns an E31 knows, some of the pixels in the OBC's display eventually go dead. The cause is a bad connection inside the OBC that permits dirt and moisture to creep in. In theory, it is possible to remove the OBC and then clean the connection. (Mr. Holm is the resident expert on this procedure.) The more expensive fix is to replace the entire OBC, which sells for about $250. If you are mechanically adept, you can remove and replace the OBC yourself.]

1) Remove the vent grill directly above the console. There are two upper and two lower tabs that need to be depressed in removing the grill. Make sure to slide the unit to the right as you pull up because the grill piece is locked behind its neighboring part. Put the vent on top of the dash. (I put a cloth down on the dash first, the air vents are a little dusty.)

2) Slide a clean putty knife between the bottom of the OBC and the dash face plate. This ensures that the catch mechanism for the OBC is depressed. The catch mechanism on the bottom almost runs the full length of the unit.

3) Underneath the removed vent you will find a sheet of black plastic held in place by a small Phillips screw on the left side of the opening. You don't need to remove this sheeting. You can maneuver your hand around the plastic sheeting on either side to gain access to the back of the OBC unit.

4) Gently push the OBC out on both side till you fell the unit stopped against it's latching mechanisms. Using another putty knife, or a small flathead screw driver, depress the latch mechanisms. There are three on the top side evenly placed along the top. The unit should easily slide out at this point.

5) If you are just replacing the unit, simply unlatch, reattach and slide the new unit into place with a click.

[If you are going to attempt to rebuild your OBC, consult Mr. Holm's directions posted previously. PMB]

Stephen Spears

--------------------------------------------------------------------------------

>I have a problem with the display of my onboard computer.<

Don't we all... The OBC is probably one of the most notoriously failing electronic items on BMWs.

It's a rather stupid construction, as it relies solely on a tiny plastic piece to hold a 200-or-so-pole connector in place. We´re lucky not to be in outer space with a ship of that build quality.

I eventually got around to fixing my own OBC. I must warn you, this is one serious "can of worms", they really built the OBC to be unserviceable - except for changing the bulbs, which can be done from the outside. I haven't figured out the "definitive DIY fix" yet, but there is a simple method, the "QD Solution" to the pixel flicker.

Firstly, you need to determine whether you have a "Siemens" or a "Borg" OBC. The factory part # sticker will tell you this. The Siemens is basically self-explanatory once you figure out how it's opened, the Borg is a real PITA (just like its Star Trek counterpart and needs extra caution when opening.

The LCD is connected via a flexible lead (etched ribbon strip). One end is sealed into the LCD, the other is glued onto the printed circuit board (PCB) and is held in place by means of a rubber-like padding under the plastic lamp reflector assembly. The problem area is, of course, where the flexible cable meets the PCB. Dirt "creeps" in via the air travelling through the front panel (you can see the black stuff inside the white plastic), and eventually gets under the ribbon-cable. Smoke is of course detrimental to a setup like this.

To clean it properly, one wants to remove the ribbon strip, but after that you really have some trouble putting it back in place as the glue is a one-time-only type, and there is some sort of heat-molded graphite stuff connecting each of the poles. I still haven't figured out how to fix this, so don't try to remove the cable.

What you do instead, is to spray contact cleaner from the back, so that the fluid goes between the PCB and the ribbon strip. I even tried spraying directly from the front, in the lower part of the LCD, and this actually worked on my friend's -95 328iA cabrio (also equipped with a "Borg" OBC). So, that should be tried first before the procedure below.

>Hmm. Does this means it might be possible to leave the OBC installed and >just spray contact cleaner into some "crevice" that will permit it to flow >to the spot where the dirt builds up and shorts out the pixels? If so, >that's a revolutionary fix for a niggling problem that affects all E31s to >one degree or another. Anybody else try this? PMB

To clean "Borg" brand OBC from inside (the Siemens is similar but needs no further explanation to open):

1. Ignition off. Lights off. Take out the OBC by first removing your car stereo (disconnecting it is not necessary if it has original cabling) then pressing the plastic flap under the OBC inwards. The plastic flap covers 2/3 of the OBC bottom width and has two hinges at each end. Be careful if you have the wooden center console, the small strip of wood between the stereo and the OBC cracks easily. The OBC pops out. Remove the connector (one on Borg, but I've seen Siemens models with two connectors). Connector comes off by pressing the striped plastic "button" and folding the plastic lever over it. It's a rather crappy plastic connector, so be careful.

2. Make sure you have a reasonably anti-static work surface and clothes.

3. Disassemble the OBC: press the four black plastic hinges inwards, loosening the corners one at a time. The hinges are located at top and bottom rear corners. The back piece will now come off.

4. Locate the two black "fork type" plastic hinges holding the PCB in place, they are equidistant from the center of the PCB. (I think that "PCB" stands for printed circuit board. PMB) The plastic hinges are pressed together using a small plier or similar, allowing them to slip through the rectangular hole in the PCB. There are two white plastic hinges on the outer sides of the OBC holding the whole lamp assembly, these need to be depressed a little to allow the PCBs and LCD to come out of the box. It takes a little fiddling and some force to get it all out, but it can be done. Be careful not to apply too much pressure on the LCD itself, as it is made of glass. The LCD holder is a frame that runs all around the LCD, this has a tendency to get stuck on the way out. More fiddling required, and a good level of tolerance.

5. Now the white connection strip between the backlight lamp assembly and the LCD should be visible.

Do NOT attempt to remove the lamp assembly, it is soldered and holds the flexible cable in place. Clean the connection pads on the flexible cable with spray-on cleaner. Suitable cleaning agent is an alcohol or freon based spray, or any good quality contact cleaning spray without oil. Do NOT use 5-56 or similar greasy products, or graphite spray. Do NOT attempt to loose the flexible strip from the PCB edge connector (it won't go back that easily, as I've found out...).

7. Clean the LCD front while you're at it (you may find collected grime at the edges).

8. Reassemble in reverse order. Make sure the flexible cabling is not damaged, and that the LCD is in no way bent.

Now, I just need to figure out how to put my own OBC back together...

This is, by far, the most comprehensive report to date in respect of repairing the infamous dead pixel problem without replacing the entire OBC. Definitely a SUPERB piece of work. Hats off to Mr. Holm for being willing to experiment on his car and for being willing to write it up for us. Of course, as Mr. Holm candidly notes, it is not the last word. If anybody has additional information based upon their own experience, please pass it along. PMB

Magnus Holm

I took apart the OBD (the in-dash LCD display) the other night to see if I could restore some lost pixels and thought I'd share some info that may be helpful for those of you DIY types out there.
When I ran the pixel test I noticed that there were no single pixel faults, but that there were entire columns of pixels out. The pixels that were lit were of fairly uniform brightness, and by touching the display lightly I could "turn on" the stuck columns, so I was encouraged.

I took the unit out according to the directions posted in the archives, and found that I had a Borg display. After getting the back off of the unit I found a pretty clean interior, with none of the dust problems that the other OEM design apparently has. I was hoping to see an obvious problem such as a loose connector, but no luck there. After poking around a bit I noticed that the main printed circuit board (PCB) was pretty "clean" (from a workmanship point of view), but that the solder joints at the connection of the flat cable to the PCB were badly corroded. Clearly the OEM used an acid core solder to assemble the cable to the PCB. Acid core solders are great timesavers when you have to solder to a surface that you don't want to take the time to clean properly, but over time (years) the remaining acid reacts with moisture in the air and destroys the joint. That had happenend here, and the corrosion was obvious.

The correct way to cure the problem is to disconnect the cable from the PCB, remove as much solder as you can with a wick, and then do a thorough cleaning of both the cable and the PCB. Most people don't have the equipment to do this, and those of you who do know what to do next. For those of you who don't have the equipment or patience to do a cleaning, simply re-solder the connection with a standard rosin core solder. This will restore the connection and should last many years. This process applies to both ends of the cable (the PCB end and the display end). I was missing about 30% of my pixels before, and re-soldering these connections restored all of them.

PS Just so you know, these displays are not active electroluminescent, but simpler (and less expensive) backlit LCD. The displays themselves therefore cannot "burn out" as some seem to think. All the power for the lighting of the display goes into the backlight incandescent bulbs, and the pixels simply act as addressable shutters for this light. Also, if for some reason you would prefer a white-on-black display, you can remove the color gel from between the bulbs and the display.

The cable shown in this photograph, is the cable which connects the front panel switches to the main PCB. Unless you are having a problem with switch response I would leave that cable alone. There is a similar flat ribbon cable which runs between the display PCB and the main PCB, and that's the one I was was referring to in my post. On my OBD, the solder joints at the cable/display PCB interface were done by machine and were in good shape. The solder joints at the other end of the cable, at the cable/main PCB interface, were hand-soldered and those were the ones I re-did.

BTW - in the Borg unit there are no "contacts" to clean. Everything is soldered in place. It's just that the soldering was badly done.

Scott

Check the following areas of your cooling systems :

Check Gauge for proper function.

Radiator Cap, later recall replacement

Anti-Freeze Fluid Level & age of coolant

Check Belt for condition

Check Belt tensioner

Fan - Clutch working?

Fan - Blades damaged?

Fan - Thermo switch not working.

Thermostat - Verify in Boiling water.

Radiator - Leak - corrosion

Hoses - Leaks - cracks - hard - plugged

Water Pump - Leak corrosion debris or Noise.

Front Air Dam - attached properly - No Debris

Upper and Lower baffle/trays - secure

Engine timing - Computer - Chips

Inside engine Cooling channels clogged -rare

Blown Head gasket - special fluid check,& water in oil

Cracked head or block, requires special testing.

Aftermarket additional fans??

Aftermarket water spray in front of radiator for Extreme conditions for a short time.

It happened again. A low-level life form managed to scrape the front corner of my 850 while it was parked in the deck at my office - and leave no note. No broken parts, but enough scraped paint to require a R&R of the front trim of the car.

I've become a pro at this now, having removed and reinstalled the front trim three times now (first time for the oil cooler installation, second and third times to remove and install parts needed for painting). While it's still fresh in my mind, I'm going to write up the procedure with as much detail as I can recall so that any other DIY'ers among us can undertake such projects as factory oil cooler installations, etc.

1. Elevate front end of car

2. Remove front tires

3. Remove "flash-to-pass" light bars (pull out air inlet grilles next to

light bar by giving a firm tug at each end; remove upper and lower screw on each light bar assembly (inward side, middle two screws are for light adjustment), and tilt light assembly horizontally outward and then straight forward to remove "arms" from mounting holes at the rear. Unscrew wiring harness connectors).

4. Remove forward facing covers from front wheels wells (this is the piece the brake duct discharges through. These are held in place by several 10mm head fasteners and one screw on the bottom lip. Removing these will expose the air collectors.

5. Unscrew the first two fasteners on each side of the wheel well liners, and bend back to catch and hold them on the brake calipers.

6. Inside the rectangular opening on the lower air collectors (for the CSi front air dam, anyway) is a screw which mounts the air dam mounting bracket to the collector. Remove these screws.

7. Remove the large splash shield which covers the front of the lower engine (held in place by four large fasteners.

8. Disconnect the alternator air inlet hose.

9. Remove headlight assemblies (I debated adding this step, because the purpose of this is to provide easy access to the air inlet hoses which connect the lower air collectors to the air filter housing boxes. It's not so much a problem to loosen the clamps when removing the front cover, but trust me on this one - based purely on personal experience - you'll be very glad you have full access to these air bellows when your reinstalling. I've done it both ways, and this most recent being my third time, all I can say it was SO MUCH EASIER to realign and connect up the air hoses with the headlight assemblies out of the way).

10. Loosen clamps on air filter housing to lower air collector housings and pull hoses off.

11. In the area behind the two air inlet grilles (already removed), there is a 16mm bolt which attached the front bumper and cover assembly to the bumper shocks. Remove this bolt on each side.

12. On the top, there are six screws with large black washers which secure the top of the cover to the front chassis. Remove these and be sure to also remove the little spacer washers in the holes.

13. At the lower air opening, there are three screws which hold the inner air snorkel (which directs air coming in the kidney grilles)to the lower bumper cover/air dam. Be sure to remove these screws.

14. You are now ready to remove the entire front cover (upper and lower air dam) as a single assembly. Make sure to place a large blanket, moving pads, or big towels on the floor to place the painted parts on when they are removed from the car. Gently tug straight forward. The sides are held in place by a slide-in bracket. This piece is reasonably heavy as a single assembly, so be prepared for the weight of it when it clears the bumper shock mounts.

14. Set the assembly down on the pads.

15. To separate the upper from the lower assembly, you must remove the the slide in plastic retaining g clip on each side of the lower cover by pushing upwards. Next remove the single screw at the wheelwell opening on each side. The lower cover will now slide out from the upper cover.

16. Depending on how much further disassembly must be done, you will find that the bumper, the center air duct, and the lower air boxes are all held to the cover by plastic rivets. You can remove these as needed.

17. The two kidney grilles are installed from the rear and are held in place by four clips, one on each side.

18. The BMW roundel emblem is secured from the rear by two small circular clamps and adhesive tape backing. To remove this, you must first remove the clamps before gently prying up the emblem.

19. Installation is basically reverse of above, except that I would install the upper cover first, and then add the lower cover /front air dam after the upper cover is completely mounted.

20. Final step is to properly realign headlights in hood openings and adjust horizontal levels as needs.

Anyway, I put my car back together after getting the painted parts back from the shop (they did it for me in only four days this time) and it was sure nice to have it back on the road. And the front end looks brand new again.

Steve Castle

Supercharged with Silicon

The Dawn of the Digital Hot Rod!

By Barry Winfield

As six hot cars career along the Firestone test track at Fort Stockton, Texas, competition and apprehension reign among one group of spectators: the guys who, to the tune of more than a half a million dollars, have tweaked these cars into terrifying shape. Taken together, these six monsters produce 2,400 horsepower - enough to run a fleet of stock Toyotas or Fords. A Corvette modified by drag racer John Lingenfelter scarfs up the long, banked track at 189 mph. Race driver Peter Farrell's dangerously red Mazda RX-7 has been pumped up from the stock 255 horsepower to a mind-boggling 360. A transmogrified BMW 850 boasts a V-12 engine that now belts out 475 horsepower. A flag-yellow Mercedes-Benz 500SL - upgraded by RENNtech of Delray Beach, Florida - struts its US$200,000 stuff, running out of revs before it runs out of power: It screams off at 182 mph and 6,200 rpm.

The aim here, obviously, is to go as fast as physics will allow. In the not-too-distant past, cars were hot-rodded exclusively by the addition of larger carburetors, free-flowing exhausts, high-compression pistons, wider camshafts, or big bore jobs. Some of these techniques are still in use, but any engine modification these days also requires new engine-computer chip strategies to manage the revised operating parameters. The revolution in automotive electronics has spawned an $80 million industry supporting more than a dozen aftermarket chip companies.

Thus, with the BMW 850, the original engine's computer chip was ditched. With it went the 155-mph automatic speed limiter that many current German and Japanese manufacturers have adopted. In keeping with the car's brutal new persona, the replacement chip promises a much less sanctimonious attitude.

The car's tuners - from a company called AutoThority - have already run the car faster than 155 mph, and they are confident that their various tweaks will see it clocking top speeds in the 190-mph range on the Texas circle track. As the car pulls out, a ripple of interest runs through the assembled participants. But then, to our collective surprise, after streaking eagerly to 170 mph, the car hangs there as if held back by an invisible rein. It turns out that the BMW, which sports an all-electronic fly-by-wire throttle system instead of the mechanical linkage most cars use, has two speed limiters. The first one is in the engine-control module chip, the second - at a slightly higher speed - is in the throttle-control circuitry. The guys from AutoThority are mortified.

Such are the pitfalls facing aftermarket car-computer hackers, those guys in the arcane business of recalibrating the chips in car engines to defy the original intentions of their makers.

Now, car manufacturers are not by nature killjoys, but among the factors they must consider when setting up the many values that control the function and performance of an engine are drivability (the smoothness, response, and predictability of a car), durability (manufacturers have to stand by their products for many years and many thousands of miles), and, of course, exhaust emissions (the car has to meet federal or state tailpipe regulations, for a specified period of time, under warranty).

Some owners are less preoccupied with these considerations than they are with power and speed. These people give performance a higher priority than durability. And, until recently, many of them neglected tailpipe emissions altogether. But that's not an attitude the aftermarket chip industry can afford these days. Thanks to aggressive policing by the Environmental Protection Agency (EPA) and by the California Air Resources Board (CARB) (much of the car chip aftermarket is, predictably, in California), aftermarket automotive companies have to be sure - dead sure - that they do not degrade the exhaust quality of a car they modify. The penalties are dire, with hefty fines levied for each car modified. A few year's worth of vehicles on the wrong side of the law, and you're as good as broke. And manufacturers will void vehicle warranties if aftermarket modifications cause cars to fail legal emissions requirements.

Not to exaggerate the problem. Tailpipe emissions tests run by the EPA and CARB - though differing in some details - are programs run on a dynamometer to simulate a cold start followed by an urban driving cycle with periods of idling, as if the car were caught in traffic. Prolonged wide-open-throttle bursts are not tested. So some makers of aftermarket engine-control chips focus on the top end, leaving the original manufacturers' calibrations much as they were at start-up, idle, and part-throttle settings.

Full throttle at high engine revolutions often gives the big gains anyway. According to Blake Carpenter, chief engineer at Texas-based Hypertech, many production cars run quite rich (a high fuel-to-air ratio) at full throttle, with less spark advance than is optimal for maximum power. This is typical manufacturer conservatism. With that cautious strategy, the car makers are dealing with possible fuel quality fluctuations. The event they fear most is detonation, produced by too low an octane rating, too lean a mixture, too advanced an ignition spark, or a cozy combination of the lot.

(Detonation is that "pinging" or "run-on" that plagues old cars when the ignition is turned off. It occurs when the compressed fuel-air mixture explodes spontaneously in the combustion chamber instead of burning evenly across a rapidly moving flame front. If the conditions are right, detonation - or pre-ignition as it's also known - does not even require a spark from the ignition system; red-hot carbon deposits or engine parts will do. However it occurs, it's bad news, eventually leading to serious engine damage and poor performance.)

From the chip hackers' standpoint, the manufacturers' cautious approach to full-throttle calibrations leaves them some leeway. At the right levels, lean mixtures and lots of spark mean better performance. And that's where Blake Carpenter looks for it. He says many cars per-form better with more spark advance and leaner mixtures. Except, that is, for the serious performance cars. Cars like Corvettes and Camaros, he says, are calibrated close to the edge at full throttle. Their designers control detonation problems with piezoelectric knock sensors, which hear the onset of detonation, then instruct the computer to retard the ignition.

The new Corvette LT1 engine, says Carpenter, proved a real challenge: Only after a year of research could any improvements be found. Nothing in the spark and injector values was worth going after. Lots of work on what's called reverse engineering (analyzing the original equipment values) and plenty of data from fifth-wheel equipment (precision speed-measurement equipment using either calibrated wheels or an optical device attached to the car) led him to the electronically controlled coolant thermostat. It was opening at fairly high temperatures, to speed warm-up in colder climates for better heater and emissions performance. Carpenter punched in a new, cooler value (160 degrees versus the 175-degree stock setting), and the car responded with more power. The LT1, he says, likes cool cylinder-head temperatures.

This protracted investigation starkly contrasts with the routine for tamer vehicles. A 1989 Chevy Lumina Eurosport with a 3.1-liter V-6 engine had so many spark and mixture settings that the car was easily transformed. In fact, says Carpenter, the new calibrations not only boosted acceleration - shaving off about 1.2 seconds from standstill to 60 mph - but also took a surprise toll on Hypertech owner Mark Heffington: During an in-car demonstration, the fifth-wheel display unit leapt off the dashboard and smacked him in the face, chipping a tooth.

After all that, adds a rueful Carpenter, only about two chips sold for that car all year. Clearly, the Lumina is not the car performance-oriented customers snap up. Carpenter says manufacturers seldom tune for optimum power, preferring to tune for 87 octane fuel and emissions performance. By changing only the wide-open-throttle strategies, it's relatively easy for Hypertech to meet EPA and CARB certification requirements. They submit chip files to show what they're doing to the chip and usually get an immediate exemption order that allows them to sell the product. Occasionally, however, they are asked to run tests with the new chip.

Ignition and fuel strategies are only two ways to heighten performance. Modern engine control units also guide transmission function, setting shift points and locking or unlocking torque converters at predetermined points. Veteran engine computer hacker John Adrain, of Adaptive Technologies, says he remembers an Infiniti Q45 with a chip from Jim Wolf Racing that picked up 1 1/2 seconds between 60 and 80 mph by simply moving the transmission shift points 400 rpm up the dial.

Adrain would know about engine control: He invented and markets the Prompaq, a device that mounts four separate engine control PROM chips and patches into the car's computer. Any one of the chips can be engaged by a simple key switch; it loosely resembles the task-switching software on the computer this is being written on. The Prompaq is the ultimate car-tuner's toy, enabling a driver to select from various performance programs, depending on the application. Say you want a towing strategy that pushes gearshift points up, even on a light throttle, and stays rich and retarded for good cooling: Switch to Position One. Want total acceleration to dust off that pesky Camaro driver? Select Two. Handing over the car to a hyperactive valet? Switch to the chip with the 3,000-rpm cutoff point and pocket the key. Or, after parking, switch to the security chip that disables the engine. Then walk away.

Of course, Prompaq is great for aftermarket chip developers. It's an easy way to compare various configurations in back-to-back tests without carting around a laptop loaded with engine settings. But Adrain is already moving on. He has filed a patent application for a novel computer piggyback system that lends much greater flexibility to an original equipment engine-control computer. He believes that there's a real need for continual recalibration of car computers. "For one thing," he says, "the fuel formulas keep changing."

AutoThority's Paul Misencik doesn't completely agree, but he concedes that fuel quality varies quite a bit across the United States. AutoThority's approach to the chip business (concentrating mainly on Porsches and BMWs) varies from that of a company like Hypertech mostly in that it works hard to improve drivability and throttle response across the operating spectrum. It wants to make the car more fun to drive. "The wide-open throttle work," says Misencik, "is a small part of our operation."

Remapping all of an engine's operating values demands more than just tightening up the wide-open throttle parameters. Reverse engineering is so complex as to stump the pros. "Dump out the data on a chip," explains Misencik, "and it comes out in hexadecimal code. It looks like gibberish. So it's difficult to see which maps are which."

Maps are sets of values arranged in two- or three-dimensional grids. One axis may be the throttle position, another the speed of the engine at that time. The computer looks at the coordinates of these maps for data points that initiate appropriate responses. AutoThority designed graphic tuning software that allows it to identify maps and depict the various engine-operating curves on chips its technicians have never seen before. This saves days of reverse engineering. Misencik has found that data points are often not laid out for optimum smoothness and can easily be improved. The computer averages values between data points when the coordinates do not exactly correlate, so the addition of extra data points helps improve engine response and smoothness.

AutoThority may be up to speed here, but Misencik points out that as automotive technology advances, the opportunities for aftermarket work decline. Right now the company profits from the tuning habits characteristic of specific market areas. The Germans, says Misencik, almost universally tune for slow initial throttle response (for smooth driving in traffic) by maintaining relatively low levels of spark advance. All the good stuff - suitable for high-speed autobahnstorming - happens at higher revs during the deep part of the pedal's travel. By contrast, the Japanese usually go for bright initial throttle response. Case in point: the latest Mazda RX7 Turbo. "It kicks you in the butt at the first touch of the pedal," he says.

"We try to impart that eager feeling at part-throttle that Porsches and BMWs normally don't exhibit. And we spend far more development time on transitions, throttle response, smoothness, and crispness than on full-throttle work. In fact, we knock the full-throttle stuff off in a day. Because of this approach, it's harder for us to get emissions certification, and it's more time-consuming and expensive to do."

He's not kidding. The application and test procedures (using a dynamometer at an environmental research laboratory) cost the company about $4,000, not counting its own development time. That's why high-end chips can cost as much as $600 per set, compared with the hundred bucks or so asked for the cheap and cheerful variety. And although your average driver spends only 3 to 5 percent of the time at full throttle, this full-spectrum recalibration is harder to sell to the public.

But AutoThority's modus operandi suits the upscale German car market that makes up its primary business. Aside from the extra cost, it seems the right way to go. If you're going to delve into the guts of the beast, you might as well do the whole thing the way you want it.

The possibility of this kind of aftermarket intervention may signal just a brief interregnum in the course of automotive electronic evolution. It's ironic: When cars first went electronic, the public imagined the demise of end-user tinkering. We soon discovered that the new electronic architecture could be figured out and modified. But it's possible that accelerating technological innovation, combined with steadily tightening government regulations, may soon result in nonadjustable electronic controls on cars. Or will that just be the ultimate hot rod/hacker's challenge?

Adaptive Technologies: +1 (805) 488 8832.

AutoThority Performance Engineering: +1 (703) 323 0919.

Hypertech: +1 (901) 382 8888.

Jim Wolf Racing: +1 (619) 472 0680.

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Last Modified: 04:54:21 AM - May 24, 1994 PST www@wired.com

Brake Pedal Pulsates

With the car stopped and the break pedal applied, I feel a slight tap or short vibration on the break pedal at very even intervals.
It seems to happen about every 4 to 5 seconds.
I just had a full inspection done at my local dealer and the car received a clean bill of health.
This included a brake fluid flush.
I was wondering if anyone in the group has felt this and/or knows the cause.

PMB, I think your wild-assed guess is on to something.
I have a new symptom now that literally sounds related to your hypothesis.
After starting a very warm engine (and only on a very warm engine) I now frequently hear something that sounds like a hydraulic system releasing pressure.
It's a short burst that is quite loud.
I have witnessed the sound startle some people close by in the parking lot.
Its rather embarrassing I must say.
My vibrating brake pedal concerned me, but now this sound has me outright worried! My braking power is seems to be good.
As I mentioned, the car passed a full inspection by my reputable dealer.
However I cant help not to imagine the terrible scenario of losing all braking power when pulling up to a red light at a busy intersection.
Will the failure of the hydraulic system result in a total loss of brake power?
Should I take it back to my dealer and ask them to focus in on the hydraulic system?
Any thoughts (including wild-assed guesses) are appreciated.

Brad Hedlund

That is the pressure control valves opening and closing on your hydraulic system brake booster.
It is normal, but if you find that when you stomp on the brake hard and you get great resistance followed by a sinking of the brake pedal after a second or two then you may want to check your hydraulic pressure accumulator (bomb).
The pressure regulator valves themselves get old and need replaced too.

JustaGuyInOKC

I had a similar problem, it turned out to be the pressure accumulator (also known as the pressure bomb).
The problem most likely is in the hydraulic system rather than the brakes.
Remember that the hydraulic powers the brake booster, steering boost and ASC.
There is also a pressure valve in the hydraulic system that can get "sticky" with age and cause a similar sound.
Have your mechanic check the hydraulics rather than the brakes, due a complete pressure test and check for leaks.

Stan Conston

Could this be an accumulator problem?

Bertsmith

That slight bump you feel is the pressure regulator cycling.
Depending on who you consult, it's either normal or an indication of impending failure of either the regulator or hydraulic accumulator.
If the accumulator eventually fails, you'll receive a brake warning light flash when you first apply the brakes.
You'll notice a momentary loss of braking power, and then it'll grab - very disconcerting.

If it gets more pronounced, I'd have the dealer perform a hydraulic system pressure test.
Reason: If you replace the accumulator and the problem resides in the regulator, you'll destroy the accumulator in short order.

Fling, Mark F.

Sounds a bit like the ABS is coming into operation.
If the problem always happens, you could temporarily remove the ABS fuse from the under hood fuse box to see if it goes away.
The dealer should be able to diagnose such a fault with ease if it can be readily reproduced.

Richard Chapman

840Ci (1996 model)

• 4.4-liter DOHC (4-cam) 32-valve V-8 engine, 282 HP

• 5-speed automatic transmission with Steptronic and Adaptive Transmission Control

• Dynamic Stability Control

• Forged-alloy wheels are the only factory option available

840Ci(1997 model)

• Scheduled maintenance for 3 years/36,000 miles included; upgrades to scheduled maintenance for 4 years/50,000 miles or full service for 3/36,000 or 4/50,000 available

850Ci (1997 model)

• No changes for 1997

1996-97: 840Ci-850Ci

All E31 Models
• Electronic Damping System (electronically controlled suspension system) newly standard; updated technology, functions basically unchanged (optional on 840Ci)

• Automatic-locking retractors on passenger seatbelts to accommodate child restraint seats

• Servotronic power steering: vehicle-speed-sensitive variable power assist (which appeared on limited-production 1994-95 850CSi) replaces former engine-speed-sensitive system. Reduces parking effort without any negative effect on road feel.

• Exterior colors; all 8 colors were offered on both 840Ci's and 850Csi.

Added New Colors for both 850Ci and 840Ci ONLY:

• Artic Silver (309)

• Cosmos Black (303)

Deleted Colors for All:

• Diamond Black (181)