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 element (filter) for dirty or being plugged.

IGNITION SYSTEM CHECKS
^ Spark plugs. Check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits. Repair or replace as necessary.

COOLING SYSTEM CHECKS
^ Engine coolant level.
^ Engine thermostat for faulty part (always open) or for wrong heat range.

ENGINE MECHANICAL CHECKS
^ Compression test.

FUEL SYSTEM CHECKS
^ Fuel pressure. See Chart A-7. Refer to Computers and Control Systems / Testing and Inspection / Procedures / Diagnostic Charts / A Charts. Testing and Inspection

ADDITIONAL CHECKS
^ Torque Converter Clutch (TCC) operation. Use Chart C-8A. Refer to Computers and Control Systems / Testing and Inspection / Procedures / Diagnostic Charts / C Charts. Testing and Inspection

The engine speed display on a Tech 1 should indicate a RPM drop when the TCC is commanded "ON."
^ For proper calibration of speedometer.
^ Induction system and crankcase for air leaks.
^ Suggest driver read "Important Facts on Fuel Economy" in "Owner's Manual."