Poor Fuel Economy

SYMPTOM:
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)
air cleaner temperature in "Testing Procedures" in Emission
control malfunction


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