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 in
VACUUM AND VAPOR HOSE ROUTING.
Check intake manifold
and vacuum components



PCV malfunction Check PCV system in TESTING
PROCEDURES



EGR malfunction Check EGR system in TESTING
PROCEDURES



Initial timing incorrect Check Ignition Timing in ADJUSTMENT
PROCEDURES



Incorrect Spark Advance Check Spark Controls in
COMPUTERIZED ENGINE CONTROLS



Verify vehicle remains in Refer to COMPUTERIZED ENGINE
Closed Loop at steady throttle CONTROLS for
(2500 rpm) and oxygen sensor Self-Diagnostic procedures
is working