AFM - what happens when its not working proper

[M5pilot]

Just changed the AFM on the 320i.

320i is fitted with 325i throttle body and chip and it had loads of flat spots, suddenly got faster then slower etc etc. I thought the chip and throttle might not be working so well together.

Changed the AFM (Ant advised this) and the difference it made was huge.

I thought this 320i was quick before but now I understand!

Its amazing how heavily the 320i was restricted. Its a BIG difference.

The old AFM flap was so so loose! This one is how it should be. Fuel economy is much better aswell now.

[320Touring]

Another hing to add to the list

so far on saturday, i've got to clean the car, do a TB overhaul and now sort AFM

[PeteE30Tourer]

Considering the spring in the AFM is something that can be relatively easily adjusted, and that it potentially has such an impact on driveability of the car, i'm surprised no-one has come up with a way to tune these cars by playing with this.

So what are the pro's and con's of tightening or loosening this spring?

[M5pilot]

I wouldnt start playing with it, the effects are not good.

[E30BeemerLad]

in general how much resistance should there be on the flap inside the AFM, just enough so it closes promptly with a little pop when you take your finger out? Also, short of spraying a dose of carb cleaner in, is there much else to do on the maintentance side of things for AFM?

I need a good weekend spent on my car giving the tb an overhauling etc. But i'm too lazy and am usually sitting on here or out driving it!

[paulj]

I dont want to sound like a nipple but what is an AFM and what does it do

[320Touring]

I dont want to sound like a nipple but what is an AFM and what does it do

AFM=Air Flow Meter

Measures the volume of air entering the inlet manifold to allow control of fuelling

is found just behind the air filter on bmw engines

Hope that helps

[Wilson]

in general how much resistance should there be on the flap inside the AFM, just enough so it closes promptly with a little pop when you take your finger out? Also, short of spraying a dose of carb cleaner in, is there much else to do on the maintentance side of things for AFM?

I'd like to know this too!

[E30BeemerLad]

really like those wheels in black Wilson!

keep thinking about getting the spokes on my 'pinas done in the Lachs Silver so there's just a subtle difference, leaving the rim in the original silver. Thoughts?

[Cloggy Saint]

Just changed the AFM on the 320i.

320i is fitted with 325i throttle body and chip and it had loads of flat spots, suddenly got faster then slower etc etc. I thought the chip and throttle might not be working so well together.

Changed the AFM (Ant advised this) and the difference it made was huge.

I thought this 320i was quick before but now I understand!

Its amazing how heavily the 320i was restricted. Its a BIG difference.

The old AFM flap was so so loose! This one is how it should be. Fuel economy is much better aswell now.

Did you replace it with a 2.5 AFM or another 2.0?