Throttle Body Inspection
NOTE:
DO NOT adjust throttle valve stop screw. Screw is preset at factory. Perform inspection only after engine has been warmed up to normal operating temperature (cooling fan comes on twice).
- Start engine and allow to reach normal operating temperature (cooling fan comes on). Disconnect vacuum hose to purge canister at top of throttle body and connect a vacuum gauge to throttle body. Ensure there is NO VACUUM.
- Check vacuum reading when throttle is opened slightly from idle. Stop engine and ensure throttle cable operates smoothly without binding or sticking. If there are any abnormalities in above mentioned steps, check for:
- Excessive wear or play in throttle valve shaft.
- Sticky or binding throttle valve lever at full close position.
- Clearance between throttle stop screw and throttle lever at full close position. There should be no clearance.
- Purge canister port should be located upstream of primary throttle valve in full closed position.