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.
See VACUUM AND VAPOR HOSE DIAGRAMS in EMISSIONS.
Check intake manifold, and vacuum components.



PCV malfunction Check PCV system. See POSITIVE CRANKCASE
VENTILATION in TESTING PROCEDURES.



EGR malfunction Check EGR system. See EXHAUST GAS RE-CIRCULATION
SYSTEM in TESTING PROCEDURES.



Initial timing incorrect Check Ignition Timing. See ADJUSTMENT PROCEDURES
in EMISSIONS.



Incorrect Spark Advance Check Spark Controls (EST, ESC etc..).