Fast Idling

[JCooper60]

My idling speed is 1500 rpms once my engine warms up. Are there any other causes besides the slider valve or idle control unit ?

[Torque]

might be a bad ECU (engine control unit) if nothing else works for it.

[silverlea]

The problem could possibly be associated with the auto choke not switching off once engine is warm, thats if your car has that setup on it ? Is the return spring on the throttle adjusted correctly ?
Hope this helps.
Chers,
Silverlea.

[ronskal]

OK, I have the Bentley Manual here and it says the idle speed is via the Idle Speed Control Unit and Idle Air Stabilizing Valve. So I think your on the right path.

The ISCU has multiple inputs such as: coolant temp., air temp., engine speed etc.
If for instance the coolant temp. wire to the ISCU is loose the unit might think the engine is not warmed up, or the sensor could be faulty.

Idle speed is not a function of the main computer.

If you have a manual, you'll be able to go through the steps. If no manual it would be very hard to find the problem if it was'nt something obvious.

[E28boi]

Check your throttle body. You might be able to adjust the linkage to make it idle a little lower.