High HC - at High RPM

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

POSSIBLE CAUSE ACTION


Electrical misfires ^ Check ignition system.

^ SEE IGNITION SYSTEM/ OSCILLOSCOPE PATTERNS.


Vacuum leak ^ Check vacuum lines and routing.

^ SEE Vehicle Emission Control Information (VECI) label under hood.

^ Check intake manifold and vacuum components.


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


Initial timing incorrect ^ Check base timing.

^ SEE IGNITION SYSTEM/ ADJUSTMENT PROCEDURES.


Incorrect Spark Advance ^ Check Spark Controls.

^ SEE IGNITION SYSTEM/ TIMING SPECIFICATIONS.