Questions and Answers

Chevrolet Monte Carlo Has A Rough Idle Q. I own a 2002 Chevrolet Monte Carlo SS with the Series II 3800 (3.8L) engine. I am currently experiencing a rough idle in park and a slight hesitation in Drive when the RPM is low. The Monte is, of course, an automatic transmission and fully loaded, Cruise control, A/C, ABS, Fuel Injected, etc. The current mileage is 28,476 miles.

In March I had the lower intake manifold gasket replaced as well as the air filter. Two weeks after I had it back it started to have a rough idle in park. I have since added GM fuel injection cleaner, replaced the fuel filter, and had it scanned for codes. No codes were found in the computer.

The rough idle remains and I have possibly narrowed it down to the plugs and wires, valves, and/or the fuel pump. I thought it many have been a tank of bad gas so I have changed from Shell, 91 octane, to Amoco Gold.

The anti-freeze and oil are both clean and at proper operating levels. There has been a slight operating temperature increase over the course of the month, as well as a change in how the engine starts. The starter barely cranks and the engine turns over too fast as if the cold start injector is working overtime.

My guess is that the problem may not be electrical since the engine has yet to produce any codes. Which direction should I head next? Am I missing a key piece to this puzzle? Any assistance would be greatly appreciated. Thank you for your time.

John

A. This problem may have been "installed" when the intake work was done or it could just be dirty injectors. A dealer has the new tools and procedures to help in cleaning these injectors properly.