For 1990-2009 cars

1. Remove the air cleaner outlet duct.
2. Inspect the throttle body bore and throttle plate for deposits. You must open the throttle plate in order to inspect all of the surfaces.

Notice: Do not subject a throttle body assembly which contains the following components to an immersion cleaner or a strong solvent:

• | Throttle position (TP) sensor

• | Idle air control (IAC) valve

• | Sealed throttle shaft bearings

The cleaners will damage the electric components or sensors. The cleaners will damage some of these components that contain seals or O-rings. Solvents can wash away or break down the grease used on non-serviceable throttle shaft bearings. Never use a wire brush or scraper to clean the throttle body. A wire brush or sharp tools may damage the throttle body components. Do not use a cleaner that contains methyl ethyl ketone. This extremely strong solvent may damage components and is not necessary for this type of cleaning.
3. Clean the throttle body bore and the throttle plate using a clean shop towel and top engine cleaner, GM P/N 1052626 (Canadian P/N 993026), or equivalent.
4. If the deposits are excessive, remove and disassemble the throttle body for cleaning. Refer to the following procedures:

• | Throttle Body Assembly Replacement

• | Throttle Position Sensor Replacement

• | Idle Air Control Valve Replacement

5. After disassembly, clean the throttle body using a parts cleaning brush. DO NOT immerse the throttle body in any cleaning solvent.
6. If removed and disassembled for throttle body cleaning, assemble and install the throttle body. Refer to the following procedures:

• | Throttle Body Assembly Replacement

• | Throttle Position Sensor Replacement

• | Idle Air Control Valve Replacement

7. Install the air cleaner outlet duct.