High HC - at High RPM

This condition is indicated by abnormally high hydrocarbon emissions with low or normal carbon monoxide emissions during cruise (2500 rpm).

POSSIBLE CAUSE ACTION


Electrical misfires Check ignition system



Vacuum leak Check vacuum lines and routing,
check intake manifold gasket,
carburetor base, and vacuum components



PCV malfunction Check PCV system



EGR malfunction Check EGR system



Initial timing incorrect Check ignition timing,
see Ignition Timing under
ADJUSTMENT PROCEDURES



Verify vehicle is operating in Refer to ON-BOARD DIAGNOSTICS
Closed Loop at steady throttle
(2500rpm) and oxygen sensor is
working