The idle speed on my Mk2 Golf gti 8v fluctuates between 2000 - 3000 revs. When i start the car it sits at the correct 1000 revs but then gradually creeps ip to 2000 and sometimes as high as 3000. I have cleaned the idle control valve and throttle body. Replaced the engine control temperature sensor as when this is unplugged the idle speed drops to 1000 however even with the new sensor it still idles at 2000. I also replaced the cam cover breather seal. Can anyone offer any advice....
Sounds like you've still got an air leak somewhere - vac hoses or main intake pipe are normally favourite. could also be a leaky O ring on the idle adjusting screw. The revs should drop when you unplug the temp sensor. Or... are the throttle switches working properly?
check the throttle cable isn't too tight, it should hit up against the stop firmly. Also I had a problem with my idle screw unwinding itself every week or so, a new one from VW sorted it.
also look at the thottle valve stop screw, i had one the other week that the lock nut was loose and it was winding itself in, so the idles was getting faster and faster
shaungti did u ever find out what ur problem was? because i have the same problem, im pretty certain its the ecu.
Have you checked the throttle position switches on the back of the throttle body? Also check the wiring to this switch for breaks.
i had exactly the same problem on a 16v KR, after trying all of what has been said, it was a bad connection in a single pole temperature sender wire below the dizzy. think it was the green/black one. Cut the wire back, soldered a new bit of wire on the end and crimped on a new connector. cured totally. Oli.
Had the same fault on my 8v digi when I bought it, it had a 2k rpm idle, found one of the throttle switches disconnected and the loom for it was hanging down the back of the engine bay.
