Okay when i start my car, it idles up to 2k rpms, then drops to 1k, then goes back up and down, up and down and i cant stop it. All vaccum lines are hooked up. I disconnect the throttle positioning sensor and it stops reving up and down but idles really high. I adjust the flat head screwdriver bolt on the intake all the way close and still doesn't drop the idle to less then 1700rpms. I can not get my idle down. When i reconnect the TPS, the idle stays smooth but is really high and i think puts the car in limp mode cuse it runs like ****. What is causing this?

 

Make sure your coolant level is full. If it is, check your fast idle throttle valve (bolted to underside of throttle body). When it goes out it will cause fluctuating idle when cold and high idle when warm.

 

what is it, it is a valve or a screw you turn/ When you say it goes out do you mean it failes or twists out?

 

What car do you have?

 

1990 Acura integra ls b18

 

Auto or manual?

 

manual

 

Check the IAC valve, and the Fast-Idle Valve. Plug your fingers over the wholes on the inside rim of the throttle body, if it lowers you idle down to like 400, then it's one of those valves. The top one is the IACV, the bottom is the fast idle valve. If it drops only to like 1200 or 1000, then you have an intake leak. Check the throttle-body, and IM gaskets, as well as double check your vacuum lines. If that doesn't work, bleed you coolant as stated in the posts above this one.

 

Also, check the PCV valve, a crack in the valve will cause an intake leak. Also check your timing.

I had this problem for almost two years, and it ended up being my throttle body gasket.