Originally Posted by characteristics
My car is a 94 honda civic 1.5L. Lately it has been reving up and down but if i leave it idling for 5 min it stops and idles fine. But then when I start driving again then at a light it starts to rev the same way. It has never tried to die from it. But there is no check engine light on neither. I took it to a mechanic he didnt know what it was either. anyone have any ideas? Please help me!!
Hey man had the same problem. I cleaned the IACV, did a coolant flush, checked for vacuum leaks, and nothing fixed the odd idle. Today I took off the Fast Idle Thermo Valve, took it apart and cleaned it out with brake cleaner. No more odd idle. At cold start, she idles at around 1200 rpm then as she warms, falls to about 800 rpm. No bouncing idle at all. Maybe that will help you.