AFM cleaning/testing

[shogun]

Well, sometimes you also have to visit the Porsche boards. Just found this nice info
http://frwilk.com/944dme/afm.htm

[genphreak]

Great link Shogun, its a very accurate write-up. It's a pity that the author does not mention the fact that after 20 years the main spring tension has probably changed. In fact, he says at the end seomthing like "Never change the spring tensioner setting". I did, it worked wonders. I'd much rather a new spring though...

[E34-520iSE]

Here's some useful links regarding AFM's, for those who haven't seen them yet!:-

http://member.rivernet.com.au/btaylor/BMWText/technical/AirflowMeterCalibrat.html

http://www.picotech.com/auto/tutorials/fuel-injection3.html

http://www.well.com/user/mosk/AFM1.htm

And here's how to re-calibrate the air screw:-

http://www.geocities.com/stereowizard2004/afm.jpg

Cheers,

Shaun

[Derek A.]

I did all that to mine. In the end I picked up a remanned unit for $90 and it worked wonders. The trace gets worn out and starts to send out erratic signals.

[SRR2]

I wonder at what point, say in a car with a manual transmission where the AFM gets the most work, the AFM ought to be replaced. I'm sure the degradation is so gradual that it probably goes unnoticed, but it would be really interesting to see if there's a change in performance and mileage when you swap it out on a mid-to-high mileage car.

[E34-520iSE]

I had a similar thought about the degradation of the IAT sensor. Is it just a thermistor? If we all soldered in nice new ones would all our cars suddenly get a bit more lively? Do these components live forever or do they just fail like glass valves (tubes)?

Cheers,

Shaun

[Derek A.]

My car - 185,000 miles sure did - I replaced the AFM and it was a totally different car. I had the original on and off a dozen times playing with it. tried all the tricks. IN the end the remanned unit did wonders.

I got mine through Murrays :
http://www.murraysdiscount.com

lifetime warranty - no worries.

D.-

[SRR2]

You probably needn't worry too much about thermistors. They're fairly stable devices with no moving parts. Of course, it's not unheard of them to fail, but the failure rate is sufficiently low that it's probably not worth thinking about it. Their reliability is on the same order as semiconductors.