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



Faulty canister purge system Check evaporative system



[1][2]PCV malfunction Check PCV system



EGR malfunction Check EGR system



Restricted exhaust Check catalytic converter



Initial timing incorrect Check ignition timing



Incorrect Spark Advance Check spark controls



Verify vehicle remains in Closed Loop Perform Self-diagnostic procedures
at steady throttle (2500 rpm) and
oxygen sensor is working



Fuel metering malfunction Check fuel pressure
Perform injector balance test
Inspect regulator operation
(check vacuum line and return hose),
Service fuel injectors (Pressure cleaner)