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Re: Intermittent idle & stall

> A friend of mine has an 84 5000S that has developed a problem.  At start up it
> idles well and normal, but once it warms up a bit it begins to cut out.  It
> then comes back before the engine dies completely.  It does this out and back
> at about 1.5 second intervals.  There is no apparent affect while driving,
> this is only at idle.
> Is it a fuel issue?  Maybe the idle control?  I'm going to do some diagnostics
> today, but I'm sure I am apt to miss something, which will certainly be the
> problem.
> Anyone out there on the planet have any clues for what it might be?
> Thanks,
> Johann Pahlmann
> 4 Audis
> 1 Porsche
> 1 less girlfriend than last week which means more time to drive, right
> Gilford?


I've had some similar experiences on my 87 5KCST.  What has worked in
the past has been a combination of the following:

Check first for collapsed vacuum hoses.  If they are soft, they need to
be replaced.  The engine seems to be real sensitive to restricted vacuum
at idle which is somewhat overcome at cruising speed.

Next, you may want to replace the fuel filter.  For similar reasons, the
restriction is more apparent at idle.

You can also try replacing the air filter.

Look for things that restrict air or fuel.  Even a small amount affects
the balance of the engine.  If all these things don't work,
check/replace the temperature sensor.  The rational here is that alot of
engine management is run off the temperature sensor.  If this is not
working, the engine doesn't know where it's at and starts to do some
interesting things at idle.

Good Luck!

PS:  By the way, I am not a mechanic.  My brother in-law, father-in law,
and myself have all owned the 5000 breed.  We have had to deal with a
myriad of these problems over 130,000 miles of driving enjoyment?!