High Idle problem on 1993 Buick Regal?

Question

Here is the problem : 1993 Buick Regal , it's a 6 cylinder, 3800 and only has 108,000 miles on it. Runs beautiful. But when it gets down to about 25 degrees at night, it will (once every few weeks) idle fast when started (but it will NOT idle down). In fact, if I kick the gas pedal it idles even faster. If I turn off the engine and restart the car, the problem is gone. I have had 2 mechanics look at it and a few people on the Internet have offered suggestions. NO, it is not the Air Idle Control(already replaced), the ECM computer (already replaced), or the Throttle Position Sensor (already replaced). All the wires have been checked, the PCV has been replaced and there are no vacuum leaks. Also, the ohm settings on the Throttle Position Sensor have been checked. This problem never happens when it is real cold outside or if the car is in a heated garage. This is starting to piss me off. Someone must know the answer to this. Please help!

Answer 1

I have this problem with my Diesel Suburban sometimes, after its cold at night and I start it, it idles high, but if I lrt it run for about 10 - 15 seconds, shut it off and start it again, its gone. To be honest, i cant answer what it is, but if its not causing that big of a deal, just ignore it. Just my suggestion

Answer 2

On some cars the throttle body gets dirty and needs to be cleaned. The Idle Air Control valve seat might still be dirty and the new one can't seat completely. I would remove the air valve and clean the entire valve body. Also look for play in the throttle body plate. It may have excessive clearance around the shaft to housing location. Did the throttle position sensor just bolt right in? Some of these need a precision electrical measurement and adjustment to operate properly. Did you clear the computer of any codes? Try removing the battery cable from the car for 1/2 hour to clear the computer of previous run history. Reattach the cable and start it up and let it idle without touching the gas or brakes until it warms up to operating temp and then try to drive it.

This may be too obscure for this car but I had this problem where the pressure switch on the power steering system went bad and it was causing problems with the idle. It was sending incorrect signals to the computer sensing a need to increase the engine speed.

Answer 3

I recommend taking this vehicle to a quality repair facility. Look for one on the internet at ASE.com that is Blue Seal rated. This certification is the highest in the industry and only 3-4% of shops have it. A facility like this will be able to help you. A direction I think that you can start with is the Mass Air Flow sensor. This module can over report the amount of air coming in the vehicle, which subsequently causes it to add more fuel, then when it is warmer after a few minutes, it will report correctly and idle will return to normal. It is impossible for anyone to say what is happening over the internet, but I just wanted to give you a new direction as a possibility.

Answer 4

the vehicle will idle higher if it is cold. is it like revving way up does it idle down when the vehicle finally warms up. if its only running a bit faster and not slamming when you put it in gear i wouldn't worry about it. you might check your coolant temp sensor and there might also be an intake air temp sensor. these are real dependable good engines take it to a good shop spend the money letting the mechanic fix it not buying parts that don't need changed. this car should easily run a nother 100,000 miles.good luck.

Answer 5

At this point.i think the only way you will solve this,would be to have a GM tech hook a scan tool up to the car before its started and ck the readings to see if all the sensors are in specs.some scan tools have a snap-shot feature ,which enables the info to be captured and played back and viewed frame by frame.This is the best advise i can give.