High HC and CO at High RPM

This condition indicates abnormally high Carbon Monoxide and Hydrocarbons during cruise (2500 rpm).

POSSIBLE CAUSE ACTION


Electrical misfires Check ignition system.



Vacuum leak Check vacuum lines and routing. See VACUUM
AND VAPOR HOSE DIAGRAM in EMISSIONS.
Check intake manifold and vacuum components.



Faulty bowl vent/canister purge system Check Evaporative System. See EVAPORATIVE CONTROL
SYSTEM in TESTING PROCEDURES.



[1][2]PCV malfunction Check PCV system. See CRANKCASE or
POSITIVE CRANKCASE VENTILATION SYSTEM in
TESTING PROCEDURES.



EGR malfunction Check EGR system. See EXHAUST GAS RE-CIRCULATION
SYSTEM in TESTING PROCEDURES.



Restricted exhaust Check exhaust system for a restriction. See
CATALYTIC CONVERTER in TESTING PROCEDURES.



Initial timing incorrect Check Ignition Timing. See ADJUSTMENT PROCEDURES
in EMISSIONS.



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



Fuel metering malfunction

Carbureted Check carburetor passages, bleeds,
and restrictors - Internal leaks,
float level, metering rods, and gaskets.
Replace or rebuild if faults are found.



Fuel Injected Check fuel pressure.
Perform injector balance test.
Inspect regulator operation
(check vacuum line and return hose).
Service Fuel Injectors (Pressure clean).