High HC and CO -- at High RPM

This condition is indicated by abnormally high carbon monoxide AND hydrocarbon emissions during cruise (2500 rpm).

POSSIBLE CAUSE ACTION


Electrical misfires Refer to IGNITION SYSTEM.



Vacuum leak Check vacuum lines and routing.
Check intake manifold
and vacuum components



Faulty canister purge system Check Evaporative System. Refer to TESTING PROCEDURES.



PCV malfunction Check PCV system. Refer to TESTING PROCEDURES.



EGR malfunction Check EGR system. Refer to TESTING PROCEDURES.



Restricted exhaust Check Catalytic Converter. Refer to TESTING PROCEDURES.




Initial timing incorrect Refer to COMPUTERS AND CONTROL SYSTEMS.



Incorrect Spark Advance Check Spark Controls. Refer to COMPUTERS AND CONTROL SYSTEMS.



Verify vehicle remains in Refer to COMPUTERS AND CONTROL SYSTEMS.
Closed Loop at steady throttle
(2500 rpm), oxygen sensor operation
is correct




Fuel metering malfunction Refer to FUEL SUPPLY AND AIR INDUCTION SYSTEMS and COMPUTERS AND CONTROL SYSTEMS.