High HC - at High RPM

This condition is indicated by abnormally high hydrocarbon emissions with low or normal carbon monoxide emissions during cruise (2500 rpm).

POSSIBLE CAUSE ACTION


Electrical misfires Check ignition system



Vacuum leak Inspect vacuum hoses for
proper routing and damaged lines
Check intake manifold gasket area



PCV malfunction Check PCV system



EGR malfunction Check EGR system



Initial timing incorrect Check Ignition Timing, see "ADJUSTMENT PROCEDURES"


Incorrect Spark Advance Check Spark Controls, see
"COMPUTERIZED ENGINE CONTROLS"



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