1989 honda pop up idling - 1989 Honda Prelude

I have same car 1989 honda crx, what worked for car was I took the Idle Air Control Valve ( IACV ) off and cleaned it with carb cleaner. What you will need is a 12mm socket and only has two screws, and pliers to take off two small hoses attached to it.. And most important carb cleaner to clean the inside of IAVC. Plus you can also search for this on the Internet ...1989 honda crx Idle Surges! Hope this helps...

start spraying carb cleaner around the intake and listen for rpm drop.

have a mechanic set the idle for you.

I had the same problem with my 91' crx it would idle and have a low rev i adjusted my tranny cable located below the battery tray and accelerated and shifted fine afterwards

Huh? Engine diagram??? WHICH PART of the engine would you like a diagram for? Better question: WHAT are you trying to fix?

sounds like the idle air screw needs adjusted out on the carb, to slow the engine.. did you just get the vehicle, and trying to fix it up, or is this something that just happened??

may be the idle speed control valve, but first check all the vacuum lines

I would start with fuel filter. They are cheap and this is the problem they cause.

There is a warm up valve on the throttle body(should have 2 small coolant hoses). remove the valve and have someone start the car while you block the port to the valve on the intake. If that clears up the problem you can cut a piece of cardboard to mount in between the valve and intake.should straighten it out.

I had the same problem on a Rover. There was a leak in inlet manifold that was caussing the problem.
To verify, spray some sealant to temporarily seal the inlet manifold .and the eratic idling should disappear for some time.
If it does, you know there is leak in inlet manifold which you can take of and refit with a new gasket.