High CO and HC - at Idle

This condition, at idle, is indicated by abnormally high carbon monoxide AND hydrocarbon emissions.

POSSIBLE CAUSE ACTION


VERY RICH Air-Fuel mixture

Carbureted Check Air/Fuel ratio, flooding or
leaking carburetor, partially
closed choke, high fuel level (float),
and dirty air bleeds



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



Malfunctioning air pump Check Air Injection system
in "Testing Procedures" in Emissions



Faulty Fuel Evaporative system, Check Fuel Evaporative system
vapor lines, purge solenoid in "Testing Procedures" in Emissions
and valves



Fuel in crankcase being Remove PCV from crankcase
sucked through PCV valve and retest emissions



Engine misfire with Closed Loop Refer to "Computers and
fuel metering, causing system Control Systems"
to go full rich for rich trouble code,
check fuel feedback (Oxygen sensor)