5000 CSQT high RPM idle

[Alex Kowalski]

Hi Jon, and welcome to the List.

You wrote:

>My Avant was running perfect and then out of the blue today started to idle
at approx 3,100 RPM.

There are high idle problems, and then there are REALLY HIGH idle problems,
and yours sounds like the latter.
It also sounds a lot like the description from this thread back in 1995:
follow this link and read some of the symptoms.

http://www.audifans.com/archives/1995/03/msg00194.html

I think you might have a missing throttle body idle adjustment screw
(sometimes they vibrate out!) or a completely disintegrated o-ring inside
the screw housing.  This screw sets the amount of air that is allowed to
bypass the throttle plate, thereby giving you manual adjustment over the
idle.  If that turns out to be the culprit, esp. if it is missing entirely,
you are going to have to reinstall the screw and go through the entire
idle-speed adjustment procedure.  Before we open that can of worms, however,
see if you can determine if air is passing through the screw orifice on the
throttle body.

HTH,
Alex Kowalski
'87 5KCSTQ
'86 5KCSTQ