High HC - at High RPM

Symptom: High Hydrocarbons, normal or low Carbon Monoxide during cruise (2500 rpm).

POSSIBLE CAUSE ACTION


Verify vehicle remains in Closed ^ SEE COMPUTERS AND CONTROL SYSTEMS/
Loop. OXYGEN SENSOR TESTING.


Electrical misfires ^ Check ignition system.


Vacuum leak ^ Check vacuum lines and routing.
Refer to Vehicle Emission Control Information (VECI) label under hood.

^ Check intake manifold and vacuum components


[1][2]PCV malfunction ^ Check PCV system.


Incorrect Spark Advance ^ Check Spark Controls.
SEE IGNITION SYSTEM/ TIMING SPECIFICATIONS


EGR malfunction ^ Check EGR system.
Exhaust Gas Recirculation