Poor Fuel Economy
DESCRIPTIONFuel economy, as measured by an actual road test, is noticeably lower than expected. Also, economy is noticeably lower than it was on this car at one time, as previously shown by an actual road test.
INSPECTION
^ 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?
^ Suggest owner fill fuel tank and recheck fuel economy.
^ Suggest driver read "Important Facts on Fuel Economy" in Owner's Manual.
^ Check for proper calibration of speedometer.
Visual check
^ Vacuum hoses for splits, kinks, and proper connections as shown on Vehicle Emission Control Information label.
^ Ignition wires for cracking, hardness, and proper connections.
^ Air cleaner element (filter) for dirt or being plugged.
^ Remove spark plugs. Check for cracks, wear, improper gap, burned electrodes or heavy deposits. Repair or replace as necessary.
^ Engine thermostat for faulty part (always open) or for wrong heat range. Using a "Scan" tool, monitor engine temperature. A "Scan" displays engine temp. in degrees centigrade. After engine is started, the temperature should rise steadily to about 90°C, then stabilize, when thermostat opens. See Cooling System.
^ Fuel pressure. See Chart A-7.
^ Compression Test.
^ [1][2]Torque Converter Clutch (TCC) for proper operation. See Chart C-8A. A "Scan" should indicate an rpm drop, when the TCC is commanded "ON."
^ Exhaust system restriction. See CHART B-1.
^ Using a "Scan" tool, crank engine for five seconds while in clear flood mode. Start engine and check for a Code 42. An open Electronic Spark Timing (EST) line will cause poor fuel economy. Refer to Code 42 diagnostic chart for repair procedure.