Date:         Fri, 30 Apr 1999 20:22:39 -0400
Reply-To:     "John P. Flaherty" <jflaherty@PIVOT.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "John P. Flaherty" <jflaherty@PIVOT.NET>
Subject:      AFM
Content-Type: text/plain; charset="iso-8859-1"

Volks:

After replacing the temp sensor failed to cure the fuel loading problem on
my 84 GL I took it to a VW mechanic who told me that I needed a new AFM. As
I didn't have the money at that time, I took the van home. I read the AFM
posts, and worked on it today.I cleaned the contacts, and repositioned the
pointer so it glided on fresh track. Before reinstalling, I got out the OHM
meter and Bentley, and did some tests. On pins 3 & 4, I had 560 OHMs,
exactly as Bentley said I should. On 2 & 3 however Bentley didn't say what
the change in OHMs should be across the arc, only that it should change. My
results were interesting. With the throttle closed, I had the same 560 OHMs
that I had across 3 & 4. A slight opening of the throttle, (about 1/8 inch
movement of the pointer) shot this up to 1150 OHMs. It stayed there until
the throttle was about 90% open then dropped, again over about 1/8 inch of
pointer travel, to 250 OHMs.

I don't know whether resistance is supposed to increase or decrease as the
pointer moves, but in either case, I would have expected consistency. The
fact that it does both suggests to me that the mechanic was indeed correct,
and my AFM is shot. Is this a correct assumption based on this data?
Anything else I can try? Or is this normal? Bentley could certainly have
been more descriptive on this one.

Any help will be appreciated.

TIA

John Flaherty
Standish, ME
'84 GL
'74 SB