Engine Performance problem
2002 Chevy Cavalier 4 cyl Front Wheel Drive Automatic 129000 miles, 2.2 4cyl
The idle has been acting strange this winter. If it was really cold the idle would stay high about 900-1000 RPM's for the duration of my drive home about 25 minutes. However if I were to pull over on the way home and turn the car off then re-start it the idle would go to the normal range of 550 RPM.
Now that spring has finally gotten to Wisconsin when I turn the Air conditioner on, the engine idle will rev up and down between 550 to 1100 as long as the Air is on.
Lets try cleaning out the idle air control valve/its passages for a start
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.