No.14 Poor Fuel Economy: Notes

POSSIBLE CAUSE & DESCRIPTION (POOR FUEL ECONOMY)

14

POOR FUEL ECONOMY

DESCRIPTION

Fuel economy is unsatisfactory.

POSSIBLE CAUSE

Contaminated air cleaner element
Variable intake air control malfunction
Engine cooling system malfunction
Improper ATF level (AT)
Weak spark
Poor fuel quality
Erratic or no signal from CMP sensor
Clutch slippage (MT)
Improper variable valve timing control system operation
Improper coolant level
Inadequate fuel pressure
Spark plug malfunction
PCV valve malfunction
Brake dragging
Improper valve timing due to jumping out of timing belt
Contaminated MAF sensor
Improper engine compression
Exhaust system clogging
WARNING:
The following DIAGNOSTIC PROCEDURE TABLE 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 article.
  (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.