High HC at High RPM

This condition indicates abnormally high Hydrocarbons with low or normal CO 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



[1][2]PCV malfunction Check PCV system



EGR malfunction Check EGR system



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