Fast idle or very high rpm

OK THANK YOU IDLE AIR CONTROL VALVE IS NEW WOULD THE VEHICLE SPEED SENSOR HAVE ANYTHING TO DO WITH THIS

Engine Mechanical problem
1993 Chevy Lumina 6 cyl Front Wheel Drive Automatic 213000 miles

My 93 lumina idles extremely fast when first starting up after sitting for several hours(ie: overnight). The check engine light comes on. When I shift into drive the check engine light goes out but the car continues at a very fast idle. I pull out of my parked position and the car travels approx. 100 feet without touching the gas pedal. The idle then slows down to a normal condition and I proceed to apply my foot to the gas pedal. It runs fine as long as I have my foot on the accelerator, but when I have to idle at a stop light the idle surges then cuts back then surges again etc. until I accelerate once again.

Any ideas what the problem(s) is?

Try to retrieve code/s from the computer by jumping terminal A to B on the DLC. I recommend you clean out the IACV and see what happens to the idle

Thank you kindly for the great info. I cleaned the IACV and the idle problem seems to have been resolved for now.

1991 chev lumina z34 when i start it up it idles fast and check engine light comes on. drive it for about 15 sec. idles down, light goes out. whats my problem?

Let's start with what code's do you have?

Check mil codes. You can check them yourself. Place jumnper wire between A and B terminals of datalink connector. Turn key to on, no crank, the mil starts flashing, you count the flashes to get the codes. Your looking for two digit codes.

Also, take the throttle-body off and clean it, check idle air, With idle issues.

I posted how you can get your code's without a scan tool.

Engine problem
1996 Chevy Lumina 6 cyl Front Wheel Drive Automatic 176000 miles
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My 1996 Chevy Lumina 3.1L was running great. The other day when I started it, the idle immediately shot up very high. I came out from the store and started it again and it was back to normal. It was normal for two days and the all of a sudden I started it and the idle shot way up high again. The "Check Engine" light is NOT on and there are no error codes but when you start it the idle shoots up immediately. It will cruise at 45 to 50 MPH without even using the gas pedal. I have a pretty good knowledge of cars but I am stumped on this one. I won't drive it any more until I resolve the problem because I don't want to blow the engine. I'm not sure where to turn at this point. I will donate to this site but I was in a terrible car accident in August and I have had zero income while I'm waiting for my disability to go through which won't be for at least another 60 days. I only have 14.00 to my name so I can only give you 4.00 because I need to keep something in my account. This is my only form or transportation and I can't get to my doctor appointments any more. Do you have any ideas at all as to resolve this problem?

Ther is an idle speed control motor on that car, sounds like it may be sticking. Try removing it and cleaning it with carb cleaner. Might want to lube it with a lttle WD-40 before putting it back on.Located on side of throttle body, under TPS if I remember correctly

Engine Mechanical problem
1996 Chevy Lumina 6 cyl 188000 miles

After starting car (with cold engine) the car idles fast, I usually leave the car at high idle for a couple of minutes, and the only way to slow the idle is to shut the car off, then turn it back on. If the car is ran for a while (10-15 miles) and you shut the car off for 1-2 hours the idle is normal, if the car is off for any lengh off time 8 hrs to overnight, and I start it it has high idle. The check engine light is on, a mechanic checked codes and said the egr valve is bad, but this is the only code, and did not know what would cause a high idle without alot of labor (money), he suggested just keep turing car off. This is my 16 year old daughters car, I would like this to work. Do you have any suggestions ?

EGR valve can cause a very high idle, but I don't like to replace any parts unnecessarily. For proper diagnostic, we would like to have the trouble code number from the check engine light. Do you have it or can you get it from the mechanic? If you can't, drive the vehicle to your local Autozone and have them scan the computer for codes. Post the codes here and we'll troubleshoot.

The code for the check engine light is P0401.

Do not replace the EGR valve, just yet. You need to do the diagnostic first, and you may also want to check for clogged EGR port and line, PCV operations, EVAP canister purge solenoid, and MAP sensor.

Getting a little to technical for this mechanic, maybe time to take to a local mechanic.

That's OK. Just make sure that they do more than simply replacing the EGR valve, as that will not fix the problem.