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



Faulty bowl vent/canister purge system Check Evaporative System in
"Testing Procedures" in Emissions



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




Verify vehicle remains in Check oxygen sensor system in "Testing
Closed Loop at steady throttle Procedures" in Emissions
(2500 rpm), oxygen sensor operation
is working




Fuel metering malfunction

Carbureted Check carburetor passages, bleeds
and restrictors, internal leaks,
float level, metering rods and gaskets
Replace or rebuild if faults are found



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