High CO and HC - At High RPM

SYMPTOM:
This condition is indicated by abnormally high carbon monoxide AND hydrocarbon emissions during cruise (2500 rpm).

POSSIBLE CAUSE ACTION


Electrical misfires Check ignition system


Vacuum leak Check vacuum lines and routing in
"Vacuum and Vapor Hose Routing"
Check intake manifold
and vacuum components


PCV malfunction Check Positive Crankcase Ventilation system in "Testing Procedures" in Emissions


EGR malfunction Check Exhaust Gas Recirculation system in "Testing
Procedures" in Emissions


Restricted exhaust Check Three Way Catalytic Converter in
"Testing Procedures" in Emissions


Initial timing incorrect Check Ignition Timing in "Adjustment
Procedures" in Emissions


Incorrect Spark Advance Check Spark Controls

Verify vehicle remains in Refer to "Fuel Injection and
Closed Loop at steady throttle Computerized Engine Controls" for
(2500 rpm), oxygen sensor operation Self-Diagnostic procedures
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)