Arkady, the AFM eventually fails on virtually all Vanagons, from what I can tell.  It has a moving gate that is electronically connected so that it signals the amount of air the vehicle is drawing into combustion.  The gate wears and over time signals become erratic.  Since these signals are a basis for metering fuel and spark, the vehicle then runs rough, and rpms vary.  In an advanced case of failure, the vehicle experiences what is called "Vanagon syndrome," whereby the engine seems to be running ok as one goes down the road at a reasonable speed, when suddenly the engine seems to fail as if fuel has been cut off and just as suddenly, it resumes running ok.  Entire incident may be only a second or two in duration.  May run fine for miles, before occurring again.

Source?  Experience, communication from other Vanagon drivers, and explanation from two good Vanagon mechanics.

Yes, the part is expensive.  Some folks try to eke out use of the bad one by fiddling with the gate.  Someone with more experience than I have would have to explain that to you.  From what I can tell, the fix is not worth one's effort -- just frustrating as results are usually poor.

I think that GoWesty has a report available on its web page concerning this, and other shops may have information about it online, too, as I recall.

David Mc

---- Arkady Mirvis <arkadymirvis@GMAIL.COM> wrote:
> Expensive part! Are failures common? What causes the failure? What are the
> symptoms and consequences of AFM failure? Please name the sources. Ark