High HC & CO -- at High RPM

Condition: Abnormally high carbon monoxide AND hydrocarbon emissions during cruise (2500 rpm).

POSSIBLE CAUSE ACTION


Electrical misfires Check ignition system



Vacuum leak Check intake manifold
and vacuum components.
Check vacuum hose routing.
See Diagrams.



Faulty canister purge system See Evaporative Emission Control System



PCV malfunction See Positive Crankcase Ventilation System



EGR malfunction See Exhaust Gas Recirculation System



Restricted exhaust See Three Way Catalytic Converter


Initial timing incorrect Check Ignition Timing.
See Adjustments.



Incorrect Spark Advance Refer to
Computers and Control Systems.



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




Fuel metering malfunction Check fuel pressure
Perform injector balance test
Test regulator operation
(check vacuum line and return hose),
Service Fuel Injectors (pressure clean)