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"
in Emissions - Check intake manifold
and vacuum components



PCV malfunction Check PCV system in "Testing
Procedures" in Emissions



EGR malfunction Check EGR system in "Testing
Procedures" in Emissions



Initial timing incorrect Check Ignition Timing in "Adjustment
Procedures" in Emissions



Incorrect Spark Advance Check Spark Controls (EST ESC) in
"Fuel Injection and Computerized Engine Controls"



Verify vehicle remains in Refer to "Fuel Injection and
Closed Loop at steady throttle Computerized Engine Controls" for
(2500 rpm) and oxygen sensor Self-Diagnostic procedures
is working