THROTTLE BODY CARBON BUILD-UP (SERVICE PROCEDURE)

Subject: THROTTLE BODY CARBON BUILD-UP

Model and Year: 1990-92 STORM -----------------------------------------------------------------------------

On some GEO Storms it may become necessary to clean carbon deposits from the throttle body. Symptoms may include low idle speeds or slightly elevated idle speed. Sometimes it may result in an increased effort to open the throttle. No attempt should be made to adjust the idle speed or TPS as these are non serviceable items. If normal service procedures and the following Throttle Body Cleaning Procedure do not correct the condition, replace the throttle body.

Procedure:

---------- 1 . Disconnect the negative battery terminal.

2. Disconnect the mass air flow duct at throttle body.

3. Cover the throttle position sensor (TPS) and IAC valve, to protect them from overspray.

4. Block IAC air inlet passage with a shop towel to prevent cleaner from entering the passage.

5. Block throttle lever in wide open throttle position.

NOTICE: THE CHEMICALS USED IN THESE CLEANERS ARE VERY STRONG, TOXIC AND HIGHLY FLAMMABLE. DIRECT CONTACT WITH ANY RUBBER OR PLASTIC PARTS WILL CAUSE SWELLING, CRACKING, OR OTHER DAMAGE.

CAUTION:

SKIN PROTECTION AND VENTILATION TO LIMIT PERSONAL EXPOSURE ARE REQUIRED TO AVOID PERSONAL INJURY.

6. Spray GM Top Engine Cleaner, P/N 1052626 or AC Delco Carburetor Tune-up Conditioner, P/N #X66-A, using a shop towel to clean away any residue that has accumulated.

7. Use a nylon parts cleaning brush to remove heavy deposits.

Part is currently available from GMSPO.

IMPORTANT: What appears to be a small amount of accumulation may be enough to limit air flow.

8. Release throttle lever. Open and close throttle lever several times to be sure it operates freely.

9. Unblock IAC inlet passage and uncover TPS and IAC valve.

10. Connect mass air flow duct to throttle body.

11. Connect negative battery terminal.

Labor Operation Number: T1799

Labor Time: 0.3 Hours

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.