Throttle Body: Testing and Inspection

Throttle Valve Adjusting Screw:

1. The factory-set Throttle Valve adjusting screw is not used to adjust idle speed. Its only function is to provide a mechanical stop for the linkage to prevent damage to the throttle plate and housing. It should be adjusted only if the factory setting has been tampered with or changed. Refer to ADJUSTMENT PROCEDURES.

2. Check the vacuum hose fittings at the throttle valve for proper vacuum signal as some fittings can become plugged, this is due to the introduction of PCV vapors near the throttle valve. If signs of PCV residue are found, remove the intake air hose and visually check the throttle valve. Clean the vacuum fittings and throttle valve with suitable spray type cleaner as needed.