High HC and CO at High RPM

DEFINITION
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
- Intake manifold and vacuum components


Canister purge system Check EVAP system.




[1][2]PCV malfunction Check PCV system.
Testing and Inspection



EGR malfunction Check EGR system.
Testing and Inspection



Restricted exhaust Check - Catalytic converter.
- Exhaust system for collapsed/
pinched pipes and muffler damage
Testing and Inspection



Initial timing incorrect Check Ignition timing



Incorrect Spark Advance Check Spark controls




Vehicle remains in Perform O2 sensor test
open Loop at steady throttle Testing and Inspection
(2500 rpm)



Fuel Injection Check - Fuel pressure
Chart A-6 Fuel System Diagnosis
- Regulator operation,
(check vacuum line and return hose)
- Service Fuel Injector (Pressure cleaner)