1989 Buick Century Car idles high


1989 Buick Century 4 cyl Front Wheel Drive Automatic 81,000 miles

I recently discovered my car has been burning oil and leaking coolant. We filled up the oil & coolant and have been keeping an eye out on it. Not even a week after discovering the above two, the car started to idle high. When I drive it, it accelerates and is increasingly harder to make stops. The car seems to drive itself. Once in park, it makes a roaring sound and the car shakes a bit.
We found codes 42, 34, and 21. My step-dad is very sure we can fix it here at home, but I am cautious and want to bring it into a shop. I was wondering if anyone has any suggestions as to what is happening or where to start.
Also, if you could give a good picture of how the Throttle Position sensor fits back into the throttle body that would be great.
Thanks in advance.

Do you
have the same problem?
Thursday, April 2nd, 2009 AT 8:14 PM

1 Reply


1989 Buick Century Car idles high

Too fast an idle speed. If an engine without computerized idle speed control is idling too fast and refuses to come down to a normal idle speed despite your best efforts to back off the carburetor idle speed screw or air bypass adjustment screw (fuel injection), air is getting past the throttle somewhere. Common leak paths include the carburetor and throttle body gaskets, carburetor insulator spacers, intake manifold gaskets, and of course, any of the engine's vacuum fittings, hoses and accessories. It is even possible that leaky O-rings around the fuel injectors are allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft and a defective idle speed speed control motor/valve stuck in the extended (high idle speed) position/throttle position sensor. Also the throttle plate could be binding in its bore and kinked accelerator cable, coolant temperature sensor might not be operating properly misleading the computer that the engine is still cold and computer throwing fuel at it raising the idle speed.

Was this
Thursday, April 2nd, 2009 AT 9:08 PM

Please login or register to post a reply.

Recommended Guides