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. Evaporative Emissions System



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



EGR malfunction Check EGR system. Exhaust Gas Recirculation



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



Initial timing incorrect Check Ignition timing



Incorrect Spark Advance Check Spark controls (EST-ESC)



Vehicle remains in Perform O2 sensor test
open Loop at steady throttle refer to OXYGEN SENSOR TESTING/
(2500 rpm) DIAGNOSIS, TESTING AND INSPECTION PROCEDURES
in COMPUTERS AND CONTROL SYSTEMS



Fuel Injection Check - Fuel pressure
refer to FUEL SYSTEM PRESSURE
TEST/ DIAGNOSIS, TESTING AND INSPECTION
PROCEDURES in FUEL SUPPLY AND AIR INDUCTION
- Regulator operation,
(check vacuum line and return hose)
- Service Fuel Injector (Pressure cleaner)