High CO and HC at Idle

DEFINITION
At idle indicates abnormally high Carbon Monoxide and Hydrocarbons.

POSSIBLE CAUSE ACTION

VERY RICH Air-Fuel mixture Check - Air/Fuel ratio
- Engine misfire causing system to
go full rich.
- Fuel pressure regulator operation
(check vacuum line and return hose)
- Fuel pressure
Chart A-6 Fuel System Diagnosis
Perform O2 sensor test
Testing and Inspection




Faulty Fuel Evaporative system, Check EVAP system.
vapor lines and valves



Fuel in crankcase being Remove [1][2]PCV from crankcase.
sucked through PCV valve Retest emissions
Testing and Inspection