Important: Over extended time and mileage, deposits may accumulate on the back of the throttle valve plate. The source of the deposit is EGR gas. Typically these deposits pose no problem. Occasionally the deposit may accumulate to a point where perceived pedal effort is effected. This procedure should not be performed on vehicles with low mileage, under 80,450 kilometers (50,000 miles).

1. Remove the air intake duct.

Notice: Do not insert any tools into the throttle body bore in order to avoid damage to the throttle valve plate.

2. Inspect the throttle body bore and the throttle valve plate for deposits. It is necessary to open the throttle valve to inspect all surfaces.

Notice: Do not use any solvent that contains Methyl Ethyl Ketone (MEK). This solvent may damage fuel system components.

3. Clean the throttle body bore and the throttle valve plate using a clean shop towel with GM Top Engine Cleaner, P/N 1052626 or AC-Delco Carburetor Tune-Up Conditioner, P/N X66-P, or equivalent product.
4. Install the air intake duct.