Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 249 (ENGINE CONTROLS - REMOVAL & INSTALLATION)AIR INDUCTION SYSTEMSTHROTTLE BODY CLEANING PROCEDURE
1999 GMC Forward Control 5.7 R, Automatic
Throttle Body Cleaning Procedure
1999 GMC Forward Control 5.7 R, AutomaticSECTION Throttle Body Cleaning Procedure
WARNING: This page is about a different car, the 2003 Pontiac Bonneville, 2003 Buick Park Avenue, and 2003 Buick LeSabre. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
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.
- Remove the air cleaner outlet duct. Remove the air inlet screen, if applicable. Inspect the throttle body bore and the throttle valve plate for deposits. Open the throttle valve in order to inspect all of the surfaces.
- Clean the throttle body bore and the throttle valve plate using a clean shop towel with GM Top Engine Cleaner (1052626) or an equivalent product. If the deposits are excessive, remove and disassemble the throttle body for cleaning. See THROTTLE BODY .
- After disassembly, clean the throttle body using a parts cleaning brush. DO NOT immerse the throttle body in any cleaning solvent. If you removed and disassembled the throttle body for cleaning, assemble and install the throttle body. Install the air inlet screen, if applicable. Install the air cleaner outlet duct.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.