High HC & CO at High RPM

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"
in Emissions - Check intake manifold
and vacuum components




PCV malfunction Check PCV system in "Testing
Procedures" in Emissions



EGR malfunction Check EGR system in "Testing
Procedures" in Emissions



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



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



Incorrect Spark Advance Check Spark Controls in
"Fuel Injection and Computerized
Engine Controls"



Verify vehicle remains in Refer to "Computers And Control Systems" for
Self-Diagnostic procedures
Closed Loop at steady throttle
(2500 rpm), oxygen sensor operation
is working




Fuel metering malfunction

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