Please help Buick rpm's increase while parked/neutral
 

My Buick has started to accelerate uphill, the rpm's increase while idle, parked, neutral, coasting. It had a little difficulty starting a while back but starts fine now. I have no clue what's going on. Any help is appreciated. I don't drive the car much but I like to know that it will start when I need it.:(

What year, model, engine, and transmission?

I had similar problems with my 1987 Cadillac Deville, 4.1l V8 "HT4100", 4 speed automatic, TBI. I never did find out what was wrong.

1990 Buick Century, automatic transmission, I stopped by autozone to get directions and they mentioned either an air leak, injector problem, or idler setting being off...

I don't know anything about the way the Buick is set up. My '88 Escort has had that problem in the past and it was the idle speed control motor. That's one possible problem or an idle air control valve or a vacuum leak. I also had to replace the ECU in my '88 once because it would suddenly raise the idle a couple thousand RPM's.

I'm not really sure if that would be the problem. The difficulty it had starting. seems like it might be some other problem than the idle motor.

I would look for a vacuum leak. Get a can of old fashioned carb cleaner. While the engine is idling spray down the vacuum lines. If the idle drops, or the car stalls when a particular part or hose is sprayed you have a vacuum leak there.

Thanks for the tip, I was told to check for a leak but I couldn't hear one. I'll see if I can find the leak and post the outcome.

Extra air is getting in the motor somehow. Stuck throttle (cable, linkage, throttle blade), IAC motor, vacuum leak, etc.

-BC

The engine speed may increase not decrease when the flamable liquid is sprayed on the air leak as it would be adding fuel to the engine. A small spray of water could also be used as it is safer than a flamable liquid. Always good to check the gas pedal, its linkage and carpet around it too.

I've heard both carb cleaner and starting fluid being used to test for vacuum leaks. I think carb cleaner is far safer... Its always worked for me.

-Jay