High CO, Low or Normal HC -- at Idle

This condition, at idle, is indicated by abnormally high carbon monoxide emissions while the hydrocarbon emissions remain normal or low.

POSSIBLE CAUSE ACTION


Rich Air-Fuel mixture Check Air/Fuel ratio,
perform injector balance test,
test regulator operation
(check vacuum line and return hose),
check fuel pressure



Dirty air filter(s) Clean or replace




Saturated fuel evaporative canister Check Evaporative system. Evaporative Emissions System



Malfunctioning Closed Loop fuel metering Refer to COMPUTERS AND CONTROL SYSTEMS.
system - Exhaust leak or other false
indicators "Fooling" oxygen sensor to
sense a lean condition




Stuck or restricted PCV Check PCV system. Refer to TESTING PROCEDURES.
valve and/or hose