Is the vehicle petrol or deisel? Does it have fuel injection or is it carburettor fueled?
Petrol:
Normally, racing at idle with an electronic fuel injection engine is down to one of the sensors on the engine being faulty. Commonly the MAP (manifold absolute pressure) sensor. Can also be down to fuel regulator being faulty. This would normally cause an eratic idle not so much a racing one. is yours continously fast?
If it is a petrol carburettor engine then there could be a problem with the jets or chokes within the carb. It could also be something simple like a stuck choke cable (if fitted) or a faulty auto choke. You could try turning out the idle speed screw a few turns (with the engine running) to see if the idle lowers. This is the screw that appears to act as a stop for the section that moves when the accelerator pedal is pressed. Get someone to sit in the car and press the pedal while you watch which bit moves.
Hope this helps and doesn't confuse too much!
Richard, June 2006
