High CO - at High RPM

This condition indicates abnormally high Carbon Monoxide with low or normal Hydrocarbons during cruise (2500 rpm).


POSSIBLE CAUSE ACTION


Faulty bowl vent/canister purge system Check Evaporative System under
TESTING PROCEDURES.



[1][2]PCV malfunction Check PCV system under TESTING
PROCEDURES.



EGR malfunction 1. Check EGR system under TESTING
PROCEDURES.
2. Check EGR electronic controls.
Refer to COMPUTERIZED ENGINE CONTROLS.



Restricted exhaust Check Catalytic Converter under
TESTING PROCEDURES.



Incorrect Spark Advance Check Spark Controls (SCC).
Refer to COMPUTERIZED ENGINE CONTROLS



Verify vehicle remains in Refer to COMPUTERIZED
Closed Loop at steady throttle ENGINE CONTROLS for
(2500 rpm) and oxygen sensor Self-Diagnostic procedures
is working




Fuel metering malfunction

Carbureted 1. Check carburetor passages, bleeds
and restrictors - Internal leaks,
float level, metering rods and gaskets
2. 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 cleaner)