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

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