AFM Running Rough

[tom325sport]

My 325i has been running a little rough (idle was fine just on acceleration was poor) so decided to have a look for the problem. Gave it a service, cleaned the distributor cap/rotor arm and cleaned the air flow meter butterfly. This is what I found...

This is closed...



And this is open...



Should that gap/lip be there ? It looks like it's bent somehow as it won't go flat.

Anyway it was filthy so cleaned it up, put it back on and the car runs better (bar a few jerks!). Also should the butterfly be smooth when operated?

Thanks

[tom325sport]

Anyone help?

[Brianmoooore]

Is the flap not parallel to the housing? It looks like it's leaning slightly one way when closed, and the other way when open. Should operate smoothly throughout its whole travel, and certainly shouldn't tilt around its axis.
The bit that may need cleaning is the printed carbon track and rotor under the black plastic cover. The flap and housing would only need a clean if there was enough build up of gunge to obstruct the flap.
The bits under the plastic cover are fragile, and the cover should only be removed if the AFM has been tested electrically and has been proven to be faulty. Testing is simple, and involves the use of a six or nine volt battery and a meter. Details are (probably) in the wiki.

[tom325sport]

Brian - thank you for great bit of advise. Yes I left the plastic cover well alone but will get testing.
The flap is not parallel with the housing - I wonder how this has happened? The butterfly flap is still smooth on operation however.