High HC at High RPM

DEFINITION: Abnormally high Hydrocarbons with low or normal CO during cruise (2500 rpm).

POSSIBLE CAUSE ACTION


Electrical misfires Check ignition system



Vacuum leak Check vacuum lines and routing.

Check intake manifold, and vacuum components.



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



EGR malfunction Check EGR system.





Incorrect Spark Advance Check Spark Controls (EST, etc..).