I have a 91 accord with low idle. I recently did a timing belt and water pump change no problems there, but prior to changing out that stuff i had a low idle with a surge. The surge was pretty random, I would start the car and it wouldnt surge unless i moved the vehicle and let off the gas and then the idle would stop once the car was warm. Im assuming it was the FIV and i tightened down the outer ring on that. I havent heard any surge yet, but i havent driven much. I still have a low idle though. I have cleaned the idle air control valve and the throttle body with no success on that yet. Im going to bleed the coolant tomorrow and see if that helps at all. But any further troubleshooting processes before i have to throw a new idle air control valve in it? I dont see any other options yet.

thanks

 

How low? What RPMs are you seeing?

 

around 400-500 rpms with no ac on.

 

I also forgot to mention that i pulled off one of the vacuum hoses and the rpm increased to about 900 rpm's so im pretty sure that it isnt a vacuum leak.

 

You very well maybe reading the tach wrong. The first thick white line is 500 rpms, then after that the small lines are 100 rpms.

 

Have you checked your base ignition timing? If it is slightly retarded it will lower the idle rpm.