[928uk] idle speed.

[Richard Armstrong]

Take off the air cleaner and MAF, and there is a tube just inside the 
entrance to the rubber tube that the MAF goes onto. Make sure the tube 
is located properly as leaks around the barb of the tube are not 
uncommon. That tube goes straight to the control valve.

The other reasons could be:  Vac leaks, check overall vacuum,  perished 
control valve tubes. To get at the tubes and stabiliser, the inlet 
manifold has to come off.
Idle switch - you can hear it click when the pedal is depressed 
slightly. It still may be erratic, and the actual contact can be checked 
at the LH plug. (See manual)
Also Engine temp sender (has 2 outputs, 1 to each ECU). This ultimately 
was the cause of my erratic idle, and fixing it involved removing and 
replacing the connector (it has self cleaning wipers)! From memory it 
was the brown sender front right as you look at the engine.

Richard A

In message 
<20040723150725.WJKP25257.fep05-winn.mailhost.ntl.com at localhost>, 
mandy.dougan at tesco.net writes
>problem with erratic idle speed on our 1987 s4.
>when cold, the rpm will range from 800 to 2000+ rpm.
>settles down to 800 rpm when warm.
>i have read somewhere that this can be a sticking idle control valve 
>and can be cured by spraying wd40 into the valve.
>how do i get to the valve?
>any help much appreciated.
>
>steve & mandy.
>
>
>_______________________________________________