Do you mean the engine goes to 3000 - 4000 rpm by itself when you start the engine? That could be related to a major vacuum leak or a problem with the idle speed motor.
If this happens while driving, does the engine speed stay high when you take your foot off the gas pedal? If it does, look for a sticking throttle cable or something binding in the throttle body. Carefully turn the engine off without disturbing anything, then look at the two throttle body assemblies under the hood. First pull lightly on the throttle cable. If it's tight, it's sticking or catching on something. A likely cause would be the floor mat. If the cable is free, poke at each throttle body to see if one releases and goes back to idle. They are both connected through a link so you'll have to watch closely to see which one was stuck. A problem with the throttle bodies is very rare.
Do you mean the transmission is not up-shifting to the next higher gear? That would be a transmission problem, not an engine speed problem. In this case, the engine rpm will go back down when you release the gas pedal. Do you also find that there is very little power when pulling away from a stop sign? That would mean the transmission has defaulted to 2nd gear and is staying there because the transmission computer detected slippage in one of the clutches or a problem with one of the sensors. This condition will not go away until the ignition switch is turned off and the engine is restarted. The dealer or a transmission shop will connect a hand-held computer to your car to read the stored diagnostic fault codes. That will provide some clues as to the cause of the problem.
Thursday, April 2nd, 2009 AT 10:31 PM