Poor Fuel Economy

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

PRELIMINARY CHECKS
^ Perform the visual and physical checks as described under Preliminary Checks. Testing and Inspection
^ 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 being dirty or 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.

Check: Distributor vent system. Refer to Chart C-4C Distributor Vent System Check. Chart C-4C Distributor Vent System Check

COOLING SYSTEM
Check: Engine coolant level.

Check: Engine thermostat for faulty part or for wrong heat range.

ENGINE MECHANICAL
Check: Compression.

ADDITIONAL CHECKS
Check: Torque Converter Clutch (TCC) operation. Refer to TCC System, Transmission Range (TR) Pressure switch assembly. A Tech 1 scanner should indicate an RPM drop when the TCC is commanded "ON."

Check: For exhaust system restriction. Refer to Chart B-1 Restricted Exhaust System Check. B Charts

Check: For proper calibration of speedometer.

Check: Air intake system and crankcase for air leaks.