92 chevy corsica when starting engine reves real high and then idles normal what could cause this?

Hi Alexandra, Im AL the owner of Big As Auto Repair

There are several things that can cause high idle, but the 2 most common problems are as follows.

(1) You could have a vacuum leak somewhere on the engine. Here is how to check for that issue. Here's what I want you to do: Buy a can of CARB Cleaner and while the engine is running spray around the Intake Manifold, the manifold is the thing the throttle body sit on. Also spray around all the vacuum line as well. If while spraying there is a change in the idle speed then you have found your leak. If there is no change then move on to step 2.

(2) Sometimes when you have a high mileage vehicle parts begin to ware out or can also begin to stick in place. Here something you can check. Idle Air Control Motors can start sticking from corrosion build up and can cause a high idle issue. Here what I want you to do. Start the engine and let it idle, while its idling I want you to tap on the Idle Air Control Motor If it idles down to normal idle speed replace the motor. The motor mounts onto the throttle body and most of them are round. Once you replace it and start the engine you'll notice that its idling real high, :This Is Normal, just let it idle until the engine controller resets the idle speed to normal.

Hope this helps and should you need further help please visit my auto repair website. http://www.bigasautorepair.com/

Not an uncommon issue for one to idle fast while cold but , 2000 rpms is a little higher than normal. May want to check the engine coolant temperature sensor for proper voltage and the coolant level. Also, check for small vacuum leaks around the throttle body gasket.

well if it runs normal when your driving then it sounds like a gas problem or maybe you need to adjust your idle a little bit, other than that it could be fuel filter or carburetor adjustments

Could be your idle air control valve is not allowing the engine to idle properly when you put a load on it.

sounds like the thermostat stickng as when engine gets cold the choke will start workin again, causing the over reving or your electric fan is on all the time "over cooling" the engine

Idle Air Control (IAC) HAS FAILED, Check for Codes Related to this Component, and Replace as Needed

check and make sure air filter is ok, and there are no restrictions in hose to throttle body, check iac (idle air control.

sounds like a vacuum leak to me. check all of your vacuum lines for cracks or breaks. see if any are missing.

You will have a no start or stalls after engine gets hot and then cools down restarts, the sensor is on the front of the engine mounted into the cam gear cover if it is not visiable get under the, (here is a picture) car and look.