No.14 Poor Fuel Economy - Mazda 2002 6 Workshop Manual

NO.14 POOR FUEL ECONOMY

14 POOR FUEL ECONOMY
DESCRIPTION Fuel economy is unsatisfactory.
• Contaminated air cleaner element
• VIS malfunction (if equipped)
• Engine cooling system malfunction
• Improper ATF level (ATX)
• Weak spark
• Poor fuel quality
• Erratic or no signal from CMP sensor
• Clutch slippage (MTX)
• VTCS malfunction
• Improper variable valve timing control system operation (if equipped)
• 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
POSSIBLE CAUSE
• Exhaust system clogging
Warning
The following troubleshooting flow chart contains fuel system diagnosis and repair
procedures. Read following warnings before performing fuel system services:
• Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always
• Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or
Caution
• Disconnecting/connecting quick release connector without cleaning it may possibly cause
Diagnostic procedure
STEP INSPECTION
1 Inspect for following:
• Air cleaner element for contamination
• ATF level
• Fuel quality
• Coolant level
• Brake dragging
• Clutch slippage
Are all items okay?
2 Connect WDS or equivalent to DLC-2.
Retrieve any continuous memory, KOEO and
KOER DTCs.
Are there any DTCs displayed?
3 Access ECT PID.
Drive vehicle while monitoring PID.
(See F–45 PCM INSPECTION.)
Is PID within specification?
TROUBLESHOOTING
keep sparks and flames away from fuel.
death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete
"BEFORE REPAIR PROCEDURE" and "AFTER REPAIR PROCEDURE" described in this
manual.
(See F–17 BEFORE REPAIR
(See F–17 AFTER REPAIR
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.
PROCEDURE.)
PROCEDURE.)
RESULTS
Yes Go to next step.
No Service as necessary.
Repeat Step 1.
Yes DTC is displayed:
Go to appropriate DTC test.
No No DTC is displayed:
Go to next step.
Yes Go to next step.
No Inspect for coolant leakage, cooling fan and condenser
fan operations or thermostat operation.
A6E398018881W16
ACTION
F–211
F