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 Powertrain Management/Ignition System/Testing and Inspection/Oscilloscope Patterns and Waveforms.

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.

Incorrect Spark Advance Check Spark Controls.
SEE Ignition System/ TIMING SPECIFICATIONS