High CO & HC - at Idle

This condition, at idle, indicates abnormally high Carbon Monoxide and Hydrocarbons.

POSSIBLE CAUSE ACTION


VERY RICH Air/Fuel Mixture

Carbureted Check Air/Fuel ratio, flooding or
leaking carburetor, partially
closed choke, high fuel level (floats),
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
under TESTING PROCEDURES.



Faulty Fuel Evaporative system, 1. Check Fuel Evaporative system
vapor lines, purge solenoid under TESTING PROCEDURES. If OK step 2
and valves
2. Check Evaporative System electronic controls.
Refer to COMPUTERIZED ENGINE CONTROLS.



Fuel in crankcase being Remove [1][2]PCV from crankcase
sucked through PCV valve and retest emissions



Engine misfire with Closed Loop Refer to COMPUTERIZED
fuel metering, causing system ENGINE CONTROLS.
to go full rich for rich trouble code,
check fuel feedback (Oxygen sensor)