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.
Refer to 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.

Check cam timing.

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

EGR malfunction Check EGR system.
Exhaust Gas Recirculation