Poor Fuel Economy

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

POSSIBLE CAUSE
EGR malfunction.
Flange gasket leaking.
Solenoid and thermo valves malfunctioning.

ACTION
Check EGR system.



POSSIBLE CAUSE
Ignition timing

ACTION
See "Computers and Control Systems".



POSSIBLE CAUSE
Spark timing

ACTION
Check Spark Controls.



POSSIBLE CAUSE
Air management valves.

ACTION
Check Air Injection system.



POSSIBLE CAUSE
Restricted exhaust.

ACTION
Check Catalytic Converter.