No. 14 Poor Fuel Economy [MZI-3.7]: Notes

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DESCRIPTION AND POSSIBLE CAUSE

14	POOR FUEL ECONOMY
DESCRIPTION	Fuel economy is unsatisfactory.
POSSIBLE CAUSE	Contaminated air cleaner element Engine cooling system malfunction Improper ATF level Weak spark Poor fuel quality Erratic or no signal from CMP sensor 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 chain Contaminated MAF sensor Improper engine compression Exhaust system clogging 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 [MZI-3.7] .) (See AFTER SERVICE PRECAUTION [MZI-3.7] .) 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
Engine cooling system malfunction
Improper ATF level
Weak spark
Poor fuel quality
Erratic or no signal from CMP sensor
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 chain
Contaminated MAF sensor
Improper engine compression
Exhaust system clogging
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 [MZI-3.7] .)
  
  (See AFTER SERVICE PRECAUTION [MZI-3.7] .)
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.