High HC and CO at High RPM

This condition indicates 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 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



[1][2]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 (EST-ESC) in
"Fuel Injection and Computerized Engine Controls"



Verify vehicle remains in Refer to "Fuel Injection and
Closed Loop at steady throttle Computerized Engine Controls" for
(2500 rpm) and oxygen sensor Self-Diagnostic procedures
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
Inspect regulator operation
(check vacuum line and return hose),
Service Fuel Injectors (Pressure cleaner)