hey all, i have a honda Civic EK hatch with d15B A/T gearbox. when i drive the car in the morning it idles a little high i think that's normal cause it's still cold, but when the car reaches normal temp and i put it on Neutral it idles from high to low contiuously and if i put it in Park it just idles high. can anyone help me with my problem??

 

Check engine light?

 

no CEL, i checked for codes found nothing the light didn't even blink once. i've googled it and found that it COULD be the iacv or the fitv and a friend told it could be vacuum. i'll check these tomorrow to see if it works.

 

Make sure the cooling system is completely full. Check in the radiator with engine cold.

Clean the IACV, sounds like it is stuck open. Two wire IACVs should spring closed with the wire unplugged. Make sure the throttle cable goes slack and the throttle plate fully closed at idle. The FITV should be closed (hole in the bottom of the throttle body in front of the throttle plate not sucking air) once the engine is warmed up. You could try closing down the air screw in the top of the throttle body. Excessive air leaking in from anywhere will make it idle too high.

 

A clogged PCV valve will cause rough Idleing.Hope this helps