Poor Fuel Economy

DEFINITION: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, the economy is noticeably lower than it was on this vehicle at one time, as previously shown by an actual road test.

PRELIMINARY CHECKS

^ Refer to Important Preliminary Checks. Testing and Inspection
^ Check air cleaner filter for dirt or being plugged.
^ Visually (physically) check: Vacuum hoses for splits, kinks, and proper connections.
^ Perform Powertrain On-Board Diagnostic System Check. Testing and Inspection
^ Check owners driving habits.
^ Is A/C ON full time (Defroster mode ON)?
^ Are tires at correct pressure?
^ Are excessively heavy loads being carried?
^ Is acceleration too much, too often?
^ Suggest owner fill fuel tank and recheck fuel economy.
^ Suggest driver read "Important Facts on Fuel Economy" in Owners Manual.

FUEL SYSTEM CHECKS

^ Check the fuel type, quality. Refer to Contamination Testing.
^ Check the fuel pressure. Refer to Fuel Supply System Check.

COOLING SYSTEM CHECKS

^ Check the engine coolant level.
^ Check the engine thermostat for always being open or for the wrong heat range.

ADDITIONAL CHECKS

^ Check the transmission shift pattern.
^ Check the Torque Converter Clutch (TCC) operation. When the TCC is commanded ON, a scan tool should indicate an RPM drop.
^ Check the Service Bulletins for control module software updates. Check for dragging brakes. Refer to Brakes and Traction Controls.