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. Refer
to VACUUM AND VAPOR HOSE DIAGRAMS.
Check the intake manifold area
and vacuum components.



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



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


EGR malfunction Check the EGR system under
TESTING PROCEDURES.


Restricted exhaust Check the Catalytic Converter
under TESTING PROCEDURES.



Initial timing incorrect Check Ignition Timing. Refer to
ADJUSTMENT PROCEDURES.



Incorrect Spark Advance Check Spark Controls (EST-ESC) under
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