Strange Fault ...

    Car won't start (or wouldn't when I had to leave it before going away to work). Sounds simple enough ?

    Problem started a couple of days before. Took it for a fastish run of about 20 miles - no problem. Return journey ok until almost back in Norwich doing about the legal limit it suddenly appeared to have a slight loss of power (or drive) when pulling hard. Continued on for the next 3-4 miles at lower speeds to park near to the house. By this time there appeared to be a high pitched whining noise seemingly coming from the back end and the engine running lumpily. Stopped for a while, car re-started ok but again lumpy running and the whining noise. When parked lots of grinding/rattling noises from the gearbox/clutch area when running in neutral. Stopped for about half-hour then drove to a shop about 3 miles away. By the time I reached there, engine got lumpier to the stage I thought it was going to stop on me so parked in a car park - then the engine died. Could not restart it. Got a friend to pick me up and returned to house.
    Next morning returned to the car with a few tools. Tried to start it. Apart from a slight hiccup started straight off. No noise from the gearbox/clutch and no noise from the back-end.
    Baffled, drove back to the house. No problems !
    Shortly after, started it again and drove about 3 miles to the same shop area. Almost the same problem as previous day, by time I reached there, lumpy running, noise from gearbox/clutch area then engine died again and could not be re-started.
    BTW, no signs of overheating at any stage.
    Decided to open up one of the distributor caps (they and rotors + ignition leads and plugs replaced last year) - no problems and bone dry.
    Had no more time to play with it has had to go to airport to return to work.

    Got to admit I'm completely baffled by this one !
    Whats the connection between the lumpy running and the gearbox/ clutch noise ? (Noise goes away when clutch depressed)

    Sorry, forgot to add that I think the fault appears to maybe have some connection to something overheating. Once the car had cooled overnight, started first time and no transmission noise - and yet no indication of the engine overheating either time when it stopped on me ???

    Any suggestions much appreciated

    If the engine is running very badly then the irratic running cn cause the clutch bearing or input shaft to rattle about. You could also be getting some back pressure in the exhaust if the cats are damaged. The transmission or clutch would not cause the engine to run poorly as there is no crank position sensor that end . Have you tried to download any fault codes?


    8Tech.

    Yes, the fault-codes are your best bet to isolating the fault. But, it could be that you have a fault in one of the two ingnition coils that materialises when hot (internal winding insulation breakdown). Also, failing camshaft position sensors are known to give problems when the engine is hot. Either could take out half of your engine, leaving you with the symptoms you described. Check also the wiring to the Engine-control units is secure.

    Thanks guys for the suggestions.
    Unfortunately, not with the car until the weekend so can't try the codes until then.
    Have never read the codes on this car before. Have a basic code reader but have a feeling its OBD2 only. 8 series is OBD1 ?
    Is there a simple way of reading the codes without a reader or dignostics program ?
    BTW, did not replace the coils last year during my ignition refurb, so thats a possibility....

    Not sure that the 8 series, or at least the 850Csi, is OBD at all. The cheapest is probably a carsoft clone interface (ebay) with the 21-pin connector, and these will give some basic diagnostics. (One or two forum members can tell you how to obtain a much better interface than carsoft, running BMW software, for not much more.)

    You also do not have cam sensors on a V12. You have 2 crank sensors and a pair of sensors on the 6 and 12 leads. If you do need either leads or coils though, I have the V12 upgrade ignition kits in stock with 40000v coil kits and Magnecor leads complete with new sensors already fitted.


    Try and diagnose the fault first though or you could buy parts that will not cure the initial fault.


    8Tech.

    Thanks Gerry,
    If you remember, you supplied me with the Magnecors (incl sensors) last year for my ignition refurb, so those already replaced and only low mileage since.
    Unfortunately, did not replace the coils at the same time but will try the codes (somehow?) before buying any parts.

    Doesn't sound like coils to me but who knows. I have a spare pair of coils gathering dust (as a result of spend first, lazy diagnostics...) if you want to try them to rule them out, PM me. Also, Eurocarparts has original Bosch coils for £60 each so not too bad. If you do buy, bear in mind that they are handed so two different part nos.


    As for reading codes, it is OBDI and you can buy the relevant leads and software but it comes with two serial connectors. A lot of modern laptops don't have one physical serial port, let alone two. You can buy USB serial ports but expect grief. I've worked in IT for 15 years and I couldn't work it out, but I do have a low boredom threshold so maybe you'll do better. I'd take it somewhere to have the codes read.

    Nick,
    Thanks for the offer of the coils but I'll take your advice and take it somewhere to get the codes read first. If after that, its looking in the direction of the coils .....
    I've already got carsoft but could never get it to work properly. Have a serial/usb adaptor and an old laptop with a serial port (just one).
    Don't think I'll have the time this weekend to mess around trying to get carsoft to work.
    Before I take it somewhere fore the codes though ...

    Iceman
    "Stomp test" - I've heard about it before. Can you give me some details about how to do it and what to look for ?
    Meanwhile, I'll do a search if its been covered in an old thread

    Zitat von IcemanBHE;82164

    Stomp test? Easy to forget. Any BMW OBDI car will stomp test.


    Mine wont (93 Csi).

    Connecting Carsoft via USB is pot luck if it works or not. I relented and bought an old laptop with a serial port off of a mate for £30 (cost him £3k when he bought it :) ). You shouldn't have any problems with a serial port laptop.

    93 850 CSI
    hung like Einstein, clever as a horse

    IIRC on the E32 if you put a bulb in the check engine light place the stomp test does work.
    So it may also work on the Euro E31.


    They built the E31 as a true world car so almost everything that works somewhere is already in all cars or at least the wiring is there to make it work.

    It could be that the purpose of your life is only to serve as a warning to others. Mine sometimes feels that way.


    Terry


    1995 840Ci
    1991 850i
    Woodland Washington USA

    This does indeed work if you re-fit the bulb. :) (or damn well better)


    Why they didnt give it to you lads almost makes up for you getting the better options. :)


    Carsoft is crap on M70s.

    Brian
    95 840Ci 80k
    99 740i 165k
    01 740iS 30k

    Well the saga continues.....
    Got back to the car Fri night. Won't start (even after cooling all week).
    So had to cancel Sat booking to take car to diagnostics place.

    Tried Carsoft on my normal laptop with RS232/PCIMA adaptor - progam would not recognise the input.
    Eventually got my old laptop with serial port to work with Carsoft and ran full diagnostics - most modules including DDE/DME did not respond and only HKL and the instrument cluster modules came up as OK.
    ABS had error codes (I'm assuming they were error codes as in German) 15 and 7.
    Airbag had error code 17.
    So not much there to give me any clues.
    Don't know why so many modules came up as no reponse ? (I'm already excluding modules listed in Carsoft as not fitted to the 8 series).

    On an off chance, decided to try the "stomp test".
    My car appears to have a bulb in both the EML and check engine slots (at least they both light up briefly when the ignition is switched on).
    However trying the stomp test procedure a number of times brought up no blinks from the check engine light.

    So, unless anybody can come up with any suggestions about the codes etc, looks like I might have to get the car trailered to the Bosch diagnostics centre or (heaven forbid!) the stealers next weekend.

    Martin,


    sorry to hear that. Carsoft is a bit hit and miss, but on my MY'95 Csi, it does work on everything except Live Engine Data and AHK. Also, it cannot clear ABS fault codes, although it can read them.


    I'd tried the Stomp test on my car and many previous Beemers, but never had any success with it. OBD-1 was driven by California regulations and so figured that EC cars had a different software and set-up. But other people here say that it works, so I don't know.


    Perhaps you could check simple things, like whether you get a spark from each coil when you crank the engine. If you do, then the ECU (in terms of ignition) is OK and so are the crank position sensors, which do the ignition timing.

    I would take a look at the rotors and caps on the distributors first. Also, if you do need coils, my 40Kv coils are only £15 more than the cheapo's from the aftermarket, and they come with all the fittings too.


    8Tech.

    Zitat von arnie;82288

    Also, it cannot clear ABS fault codes, although it can read them.


    You sure about that, mine clears ABS Fault codes. If you have a permament fault it might look like its not clearing them.

    93 850 CSI
    hung like Einstein, clever as a horse

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