My car is idling up and down cold, warm. When it's cold and I start it it idles at about 2000 rpm then dips down to 1000 and back up, holds its position until warm and then up and down constantly. ok PVC is brand new, IAC valve is working properly. I cleaned the throttle body and thats when it started going crazy constantly. Here's the question, what on the throttle body could be bad. Its a ODB 2 B16 in a 1992 Civic Si..

 

 

aright do this.... start the car when its cold wait for it to warm up and when the idle is fluctuating unplug the idle air controll valve and see if it stops.

if it stops doing that than it could either be the idle air controll or you can do this.

take the throttle body off the intake manifold get a can of throttle body cleaner and spray the whole inside of the manifold including all the ports. there should be a port where the throttle body bolts up and it goes to the iac spray the hell outta that and spray a lot too. i used almost all the can on it. then spray the throttle body out.

put it back on start it up. ( its going to take a bit because of all the cleaner you sprayed in there. ) and see if that helps. thats what i had to do to mine after i replace the iac and it didnt do anything.

 

what throttle body are you using? does it have a fast idle valve on the bottom?...that could be your issue if you do have one. if you do have one, put your finger over the lower hole in front of the throttle plate. if your car idles normally there's your problem. could be a vac leak at the gasket when you put the tb back on...or you lost coolant when you took it off and disconnected the coolant lines and have air in the system. did you check to see if you have any vac hoses disconnected? try adjusting the idle screw cuz sometimes this helps with minor rev fluctuations.