Idles differently when cold and warm.

Ti Kan ti at
Mon Nov 5 13:51:06 EST 2001

Kate FitchGerald writes:
> [ 87 4000S ]
> When my cars is cold, the car idles much differently
> then when it's warm. I have the Haynes manual for my
> car and I've read the Chapter on Fuel Injections a
> couple of times, but, I haven't seem to pin point my
> problem.
> ...

The idle stabilizer valve is probably all gunked up inside and
needs cleaning.  Remove it and spray the inside with liberal
amounts of carburetor cleaner, reinstlal and see if that makes
things better.  On your car, the ISV is the cylindrical looking device
with one end connected to the big rubber intake boot, and the other
end with a hose connected to it.  It also has an electrical connection.

If cleaning the ISV doesn't help, note whether the ISV is making
a buzzing sound when the engine runs.  Perhaps there is a electrical
continuity problem.

Otherwise, your car needs a basic fuel injection diagnosis.  You should
follow the procedure in the Bentley manual for that.

01 S4 2.7 biturbo quattro
84 5000S 2.1 turbo
80 4000 2.0
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Research Laboratories, Sunnyvale, CA. USA
  ///    ti at

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