High CO -- at High RPM

Condition: Abnormally high carbon monoxide with low or normal hydrocarbon emissions during cruise (2500 rpm).


POSSIBLE CAUSE ACTION


Faulty canister purge system See Evaporative Emissions System



PCV malfunction See Positive Crankcase Ventilation



EGR malfunction See Exhaust Gas Recirculation



Restricted exhaust See Catalytic Converter



Incorrect Spark Advance Refer to Computers and Control Systems.



Verify vehicle remains in Refer to Computers and
Closed Loop at steady throttle Control Systems
(2500 rpm) and oxygen sensor
is working




Fuel metering malfunction Check fuel pressure
Perform injector balance test
Test pressure regulator operation
(check vacuum line and return hose),
Service Fuel Injectors (Pressure cleaner)
Refer to Fuel Delivery and Air Induction