High HC and CO - at High RPM

This condition indicates abnormally high Carbon Monoxide and Hydrocarbons during cruise (2500 rpm).

POSSIBLE CAUSE ACTION

Electrical misfires Check ignition system



Vacuum leak Check vacuum lines and routing.
Check intake manifold and vacuum components.



Saturated fuel evaporative canister
or malfunctioning vapor purge system 1. See EVAP System
If OK, go to step 2.
2. Check Evaporative System electronic controls.



PCV malfunction Check PCV system



EGR malfunction 1. Check EGR system
If OK, proceed to step 2
2. Check EGR electronic controls.



Restricted exhaust Check Catalytic Converter



Initial timing incorrect Check Ignition Timing



Incorrect Spark Advance Check Spark Controls (SC).



Verify vehicle remains in Closed
Loop at steady throttle (2500 rpm)
and oxygen sensor is working



Fuel Metering 1. Check Air/Fuel ratio, fuel pressure, and regulator operation.
2. Perform injector balance test.
3. Service Fuel Injectors (Pressure cleaner).