Air Mass Sensor

put VERY simple.

-wire is heated to a set temperature.
-air passes the hot wire cooling it.
-current is applied to maintain temperature stable
-more air flow = more current
-engine management uses this current to calculate air mass in intake.
-engine adjusts fuel mix and timing based on this

feedback from the O2 sensor in the exhaust is used in conjunction with the MAF to maintain the correct air fuel ratio and timing.

Not having one = less than optimal fuel mix, rough idle, loss of power and responce.

Zitat von Bob Beebe;85661

Does anyone know where I could obtain one please. Tried ebay and nothing found. Guess I need a breaker somewhere to remove one?

The breaker stands here



no, not the 8, but the oxford green 7

I'll have a look at the AMSs the next days...

Bob, according to bmwfans.info the air flow meter on our cars is shared with M50 powered cars, like the e36 320i and e34 520i.

I found this: http://cgi.ebay.co.uk/bmw-3-se…ts_SM&hash=item230dbecfd1

I have two spares in my garage, I don't really want to sell them but if you're really stuck give me a shout.

I would be very concerned if the MAF (Air Mass Sensor) did not have a wire in it. Another thing that some state is the oiled air filters (K & N) can cause problems with MAFs. The benefits/risks/disadvantages of oiled air filters can be extensively discussed, but to my thinking, if you put an oiled filter in the airflow, then pass the air over a very small wire, it may not be advantageous. As Noggie said, the car will run, but will not run its best without a fully functional MAF. Good luck!

care for modern air mass sensors?

I've built a little setup to enable our dear old M70 (or S70) engines to equip more modern air mass sensors.

Some pictures:
http://www.8er.org/forum/showpost.php?p=81269&postcount=122

The complete thread (in the German part of the forum) shows the whole project with all the data.

So far I've been testing the setup in my own M70 with no negative results. One can expect the new setup to behave like equipping fully functioning original sensors.

What do you guys think?

oops.. can you see these?


The idea is to design an electronics board with a processor that converts the characteristics (massflow to voltage) of the modern sensor into the characteristic of the original sensor. That way, the DMEs will not notice the difference.

The pictures display a "test bench like" setup. I merely shoved it all in there to see if it works. It's not how I would imagine a proper clean installation. But.. I found out that it does work so far.

fuzzifikation's thread is posted in the German/Swiss/Austrian club E31 club forum. The club forum is only available to paying club members. For pricing and club membership, please contact reinhard.

Here are fuzzifikation's pictures (click to enlarge):

Zitat von fuzzifikation;85723

What do you guys think?

What did you think we'd think? Awesome, of course ! Given the prices BMW demands for trade-in refurbished MAFs, this may make several E31 owners happy.

Thank you, revtor!

Pricing of original BMW MAFs is only one of the aspects - unfortunately there is not a big margin there with all the new parts ( saving a couple of hundred euros is realistic - but not a whole lot more). Availability might be another one - maybe in a couple of years those old refurbished MAFs are not available anymore? It's more the availability that this project aims for - to keep the old M70s on the road.

The biggest negative aspect so far is that it seems as if no one can get their hands on the connectors of the original MAFs. In the pictures you see sawed-off connectors (the last pic shows one) from original but defect MAFs that were donated to me for the project. However, this solution is not optimal and I am desperatly looking for those connectors!

Without these original connectors one would have to cut the wire harness before the connectors and install a coupling. That is a non-reversible alteration. Although the original MAFs could still be used, the wire harness would not be original anymore. Something that I think only few are willing to do.

In your other thread you suggested approximately 600 EUR for two sensors and the electronics. For the refurbished M70 MAFs the difference may not be that big, but a single S70 MAF goes for over 700 EUR... Plus if one of the sensors ever fails again, you only have to replace the relatively cheap hot film MAF.

But I agree the wiring and connectors will be a decisive factor to many... I hope you can find a solution for that!

Zitat von revtor;85743

..., but a single S70 MAF goes for over 700 EUR...

I'm not religious but... JESUS CHRIST!

Zitat von revtor;85743

But I agree the wiring and connectors will be a decisive factor to many... I hope you can find a solution for that!

Me too .. maybe one of the guys reading this might have an idea?

Perhaps ITT Cannon can help.
They are one of the leading connector manufacturers in the world.

http://www.ittcannon.com/content.aspx?id=370

This series might fit.
http://www.ittcannon.com/Product.aspx?id=1110

or this.
http://www.ittcannon.com/product.aspx?id=1100

Any luck finding a MAF?

I just collected a huge pile of e31 parts, and in that pile there was 3 MAF's.

Send me the Pnr of the ones you have and maybe I have one for you.
Edit: just saw the number in your first post, will check one of the next days when I go out to my garage and start sorting out the valuable parts from the junk (stuff that is broken)

"....What did you think we'd think? Awesome, of course ! Given the prices BMW demands for trade-in refurbished MAFs, this may make several E31 owners happy..."

Are the BMW supplied MAFs refurbished?

I just ordered a CSi one and I think (hope) they are new..??

I'll know when it arrives, but it was not listed as refurbished and they did not ask for my old one, which incidentally is ok, but I'd like to have a spare.

Otherwise, there are these, which seem to have the right connector, so some Chinese company should be able to make the connector adapter for using say, a Bosch HFM5 type.

http://www.onlineautomotive.co…ctID=7561&VehicleID=28616

Don't trust the 'Chinese copy' MAF's, they look good but fail to measure air-mass accurately, and let's face it, that's all they have to do! Bought one for the E38 a couple of years ago, when it went to BMW for running problems they just laughed at the innacuracy!