Poor Fuel Economy

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



PRELIMINARY CHECKS

^ Perform the careful visual checks as described in "Preliminary Checks."
^ Visually/physically check: Vacuum hoses for splits, kinks, and proper connections as shown on "Vehicle Emission Control Information" label.
^ Check owner's 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?
^ Check air cleaner filter for dirt or being plugged.

IGNITION SYSTEM

^ CHECK: Spark plugs. Remove spark plugs, check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits. Repair or replace as necessary.

COOLING SYSTEM

^ CHECK: Engine coolant level.
^ CHECK: Engine thermostat for faulty part (always open) or for incorrect heat range.

ENGINE MECHANICAL

^ CHECK: Compression.

FUEL SYSTEM

^ CHECK: Fuel pressure. See CHART A-7. Chart C-7 EGR System Check

ADDITIONAL CHECKS

^ CHECK: TCC operation. Use CHART C-8. A Tech 1 scan tool should indicate an RPM drop, when the TCC is commanded "ON." Chart C-8A Torque Converter Clutch (TCC) Diagnosis
^ CHECK: For proper calibration of speedometer.
^ CHECK: Induction system and crankcase for air leaks.
^ CHECK: Suggest driver read "Important Facts on Fuel Economy" in "Owner's Manual."