I have a problem with the idle speed on a '93 prelude SI with a 2.3 liter 5 speed. I know there have been many threads regarding idle issues with Gen 4 preludes but my problem has some unique symptoms. Idle is perfect when the car is standing still. If the car is moving at all it will idle between 2,400 and 3,000 RPM if you put it in neutral or press in the clutch. As long as the car remains rolling it will stay at this very high RPM. It remains at this high RPM until the car comes to a COMPLETE stop for about 2 or 3 seconds. Then the idle will return to normal, about 900 RPM. I have replaced the Fast Ilde valve. the IACV and the TPS. I assume the car is getting a signal from the ABS system that it is moving but why is it trying to control the idle speed when the car is moving? Any help would be greatly appreciated.

Steve P. in NC

 

coolant temp sensor maybe?? i know im reaching, but im trying to think of everything that influences idle. and thats all i can think of

 

If this happened after replaced your coolant then you probably need to rebleed the coolant system. Also check you ECT , what ashleylarry stated above. That is what will affect idle speed too.

 

Thanks for your replies.
The car has had this problem since I bought it a year and a half ago. I have not replaced the coolant but I believe the radiator was replaced about two years ago. Surely the system would not trap air for that long, would it? If so, what part of the system are you talking about bleeding?

My temperature gauge seems to work fine. Is the ECT sensor the one that sends a signal to this gauge? If not, can you point me to it.

Thanks again