Poor Fuel Economy

Fuel economy is noticeably lower than expected. Customer detects a significant reduction in fuel mileage.

POSSIBLE CAUSE ACTION


EGR malfunction, Check EGR system in "Testing
Flange gasket leaking, Procedures" in Emissions
solenoid and thermo valves
malfunctioning



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



Spark timing Check Spark Controls
Refer To Ignition Timing
In "Adjustment Procedures"


Air management valves Check Air Injection system in
"Testing Procedures" in Emissions



Air damper door binding, Check inlet air temperature system (HAI)
air cleaner temperature in "Testing Procedures" in Emission
control malfunction



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



Malfunctioning Closed Loop Perform Computer Feedback
Fuel Metering System System Tests