It sounds like you may have a valve ping problem. It could be caused by a couple things. One of which is a low octane fuel. Try getting premium fuel once to see if that helps. If not, it could be a knock sensor.
A knock sensor allows the engine to run with the ignition timing as far advanced as possible. The computer will continue to advance the timing until the knock sensor detects pinging. At that point the computer retards the ignition timing just enough for the pinging to stop.
A knock sensor assures that you're getting as much power and fuel economy as is possible from your engine.
Let me know if this helps, or if you have any other questions.
Friday, October 24th, 2008 AT 3:43 PM