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 in
VACUUM AND VAPOR HOSE DIAGRAMS
Check intake manifold
and vacuum components



Faulty canister purge system 1. Check Evaporative System under
TESTING PROCEDURES.
2. Check Evaporative System electronic controls.
Refer to COMPUTERIZED ENGINE CONTROLS.



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.



Initial timing incorrect Check Ignition Timing under
ADJUSTMENT 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 Check fuel pressure
Perform injector balance test
Inspect regulator operation
(check vacuum line and return hose),
Service Fuel Injectors (Pressure cleaner)