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 in
"Testing Procedures" in Emissions



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



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



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