I have a 96 civic dx, it idles real funny. I start it and it idles fine, after about 5 minutes it starts idling high then normal, high then normal. I have ruled out a vacuum leak by tryin about 5 different procedures. There is no check engine light on. When I do unplug the map sensor it idles fine... so I replaced the map sensor hoping it would fix the problem, and yet it hasnt. Any ideas guys? ( and it still idles normal when I unplug the map sensor.)

 

Try cleaning the IACV on the throttle body and also topping off and bleeding the cooling system.

 

replace the IAC valve

 

I have indeed cleaned the IACV, and also have bled the cooling system and topped it off. The problem persists. My lights are also dimming with the idling issue. Possible alternator bad? this is a headdddache!!!!!!!!!!!!!!

 

AutoZone will check your alternator and battery free of charge.

Is the engine overheating or loosing coolant?

How did you bleed the cooling system?

Have you tried adjusting the idle screw on the throttle body?