No. 14 Poor Fuel Economy: Notes

SYMPTOM TROUBLESHOOTING - NO. 14 POOR FUEL ECONOMY [L3]

14	POOR FUEL ECONOMY
DESCRIPTION	Fuel economy is unsatisfactory.
POSSIBLE CAUSE	Contaminated air cleaner element Improper ATF level (ATX) Brake dragging Clutch slippage (MTX) Improper coolant level Poor fuel quality PCM DTC is stored Engine cooling system malfunction Cooling fan system malfunction Ignition system malfunction Spark plug malfunction Excessive/inadequate fuel pressure Intermittent open or short in fuel pump related circuit Fuel pump mechanical malfunction Fuel line restriction or clogging Fuel leakage from fuel injector Fuel injector is clogging Improper operation of variable tumble control Improper operation of variable valve timing control system Improper operation of variable valve intake air control Exhaust system clogging Contaminated MAF sensor Low engine compression Improper valve timing PCV valve malfunction WARNING: The following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read following warnings before servicing fuel system: Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this service information. (See BEFORE SERVICE PRECAUTION .) (See AFTER SERVICE PRECAUTION .) CAUTION: Disconnecting/connecting quick release connector without cleaning it may cause damage to fuel pipe and quick release connector. Always clean quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.

POOR FUEL ECONOMY

DESCRIPTION

Fuel economy is unsatisfactory.

POSSIBLE CAUSE

Contaminated air cleaner element
Improper ATF level (ATX)
Brake dragging
Clutch slippage (MTX)
Improper coolant level
Poor fuel quality
PCM DTC is stored
Engine cooling system malfunction
Cooling fan system malfunction
Ignition system malfunction
Spark plug malfunction
Excessive/inadequate fuel pressure
- Intermittent open or short in fuel pump related circuit
- Fuel pump mechanical malfunction
- Fuel line restriction or clogging
- Fuel leakage from fuel injector
- Fuel injector is clogging
Improper operation of variable tumble control
Improper operation of variable valve timing control system
Improper operation of variable valve intake air control
Exhaust system clogging
Contaminated MAF sensor
Low engine compression
Improper valve timing
PCV valve malfunction
WARNING:
The following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read following warnings before servicing fuel system:
- Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.
- Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this service information.
  (See BEFORE SERVICE PRECAUTION .)
  
  (See AFTER SERVICE PRECAUTION .)
CAUTION:
- Disconnecting/connecting quick release connector without cleaning it may cause damage to fuel pipe and quick release connector. Always clean quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.