High HC - at High RPM

This condition is indicated by abnormally high hydrocarbon emissions with low or normal carbon monoxide emissions during cruise (2500 rpm).

POSSIBLE CAUSE

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 PCV system in "Testing Procedures" in Emissions

Initial Timing Incorrect
- Check Ignition Timing in "Adjustment Procedures"

Incorrect Spark Advance
- Check Ignition Timing in "Adjustment Procedures"

Verify Vehicle Remains In Closed Loop at Steady Throttle (2500 rpm) and Oxygen Sensor Is Working
- Test the Fuel Injection System. Refer to "On-Board Diagnostics" if so equipped