High idle

[bennyc]

1990 Olds. Cutlass Ciera S 3.3L V6

I have a problem with my car idling high, or what it seems to be high. I have no way of saying what it idles at because I dont have a tach. But its high enough, for my father and next door neighbor to bring it to my attention.

The story goes... About 6 months ago it would idle high every once and a while, then everyday. I recently had to change the computer out, now when i start the car for the first time everyday day it idles normal. But when it heats up and i begin to drive longer the idle goes up high, again i cant tell the RPM but its loud enough. I think this could potentially damage my transmission, because when the car heats up it shifts down 1st and Reverse very hard. My question is how do I correct this issue? Electrical Issue (no warnings yet)? Mechanical issue? Any help would much appreciated, this has been a pain in my butt for about 7 months.

[DIY Mechanic]

The check engine light would come on if the computer is unable to bring the idle down.

AC causes high idle [normal], low air pressure [Dirty air filter], and debris in front of the radiator are the usual suspects.

[bennyc]

Thanks for the info.

I checked the air filter and changed it (it was time anyway). I drove about 15 miles and begin too idle too high.

I also checked in front of the radiator, and that checked out ok.

And the A/C doesnt work, so i dont use the system.

Any other troubleshooting ideas would be much apprieciated.

[HeldtheViolets]

Try the idle control sensor/throttle control sensor.. that was my problem with my 92 cutlass ciera.. I got a new one and while it still idles high, it just takes some adjusting.. run and error code and see what you get maybe?

-Elisha

[djnoname]

My 93 ciera (3.3l) idles way to low and upon reading some of the older posts I discovered the following..... on those sensors. Since yours is way to high you probably have the same malfunctioning sensors.
You have four sensors that work all in conjunction with the throttle body and C3I ignition in management of idle, driving, fuel/air delivery to your injectors. If any gave out then your idle will be to high/low and car may stall not drive correctly at higher speeds either.
IAC (idle air control sensor) controls your idle speed and charachteristics it's like $70 and probably will make a big difference if cleaned or replaced. Kind of hard to get screwdriver there but it's to the right of air filter housing when you are standing on drivers side fender. Has two screws and plastic wire clip. It screws out and for the new one you have to push back spring and little bar (pintlr) to less then one inch then install and turn your key to "ON" (but dont start) for 5 sec then "OFF" for 30 sec and this will reset your pintle to where it needs to be for proper idle. Then start car and check your idle. Should be correct but pushing back pintle and then resetting it is about the only idle adj possible on 3.3L.

Cleaning your MAF sensor (black box with A B C wires to left of air cleaner housing) will help driving performance. Open box and gently clean what looks like inside of lightbule with carb cleaner and rag. Then put back the way u found it.

replacing your TPS (throttle pos sensor) which is the black sensor to the left of your maf sensor box is a good idea but not necessary if your idle is good after replacing your IAC. Its around 50 bucks but if you can afford it this will also help your IAC sensor work better as well as cruising performance. It is not easy to access due to tight fit though.

Lastly is your CTS (coolant temp sensor) which is right above your water pump. This really helped my idle and is really cheap $19 and the easiest sensor to replace. There are two sensors above your water pump and the CTS is the one towared front of car. Unplug clip, use 19mm socket and replace.

Remove your air cleaner housing for IAC & TPS sensor replacement and unplug neg batter cable b4 any of the above.

[sugarmagnolia07]

Pop the hood and look at the vacume hose(s) that are closer towards your wind sheild. On my car when the idle was running high one of them had popped loose. I noticed because when I was in park the idle would never fall lower than 1rpm.