ignition problems (i think) somebody please help!!!!

Huw Powell audi at humanspeakers.com
Wed Dec 17 13:06:18 PST 2008

3k is an odd place for the cutout - around 5k is typical of a 4 cyl fuel 
pump relay, around 1500-1800 is typical of a "stuck closed" idle switch 
(which you might want to test to make sure it's working).

One thought I have is that you might have a dead spot on the 
potentiometer on the side of the air/fuel box.  It's hard to get to on 
the type 89, being "under" the edge of the fender.  To check it you need 
to put a meter on it (two different ways) and slowly raise the air flap 
through its range of motion.

Only problem with that theory is it's not rpm-related really, it's more 
related to pedal position/air demand.

One thing in its "favor" is that some of the trip computer functions use 
the pot signal (fuel economy readouts, mostly).

What have you replaced or tested so far?  Have you checked the ignition 

> i'm driveng an '88 90 quattro 5 cyl.this problem has been escalating
> for a while and now the car is not driveable. it started out that the
> engie will cut out at 3000 rpm kind of like a rev limiter.i found if
> the fuel meter on the front of the cis fuel meter is unplugged, the
> car will run fine...but the onboard computer goes to all zero's when
> 3000 is reached. i've tried swapping just about everything i can
> think of but i can't finnd the problem and now tthe car won't idle or
> run properly. it surges stalls and backfires(blew the side out of the
> muffler when it backfired).i'm at a loss and running in circles.if
> anyone thinks they can help, please do.

Huw Powell



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