Genuine Pontiac Grand Prix Throttle Body

Pontiac Grand Prix Throttle Body Parts Questions & Answers

• Throttle Body Assembly
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  Q: How can you detect and fix a vacuum leak at the bottom of the throttle body?

  A: The TBI throttle body is attached to the top of the intake manifold by two bolts. They can sometimes work loose from vibration and temperature changes during normal engine operation, causing a vacuum leak. If you suspect a vacuum leak at the bottom of the throttle body, use a rubber hose as a stethoscope. Start the engine and place one end of the hose next to your ear as you probe around the base of the throttle body with the other end. You will hear a hissing sound if a leak exists, but be careful of hot and moving engine components. Remove the air cleaner assembly. Locate the throttle body mounting bolts. Determine if any special tools or adapters will be necessary to tighten them. Tighten the bolts securely and evenly. Do not overtighten them, as the manifold threads could strip. If, after properly tightening the bolts, a vacuum leak still exists, the throttle body must be removed and a new gasket installed. After tightening the fasteners, reinstall the air cleaner and return all hoses to their original positions.