NO.14 POOR FUEL ECONOMY [LF]
POSSIBLE CAUSE & DESCRIPTION (POOR FUEL ECONOMY)
correct?
No
Inspect for cause.
5
Install fuel pressure
gauge between fuel
pipe and fuel
distributor.
Start the engine and
idle it.
Measure fuel line
pressure during idle.
Is fuel line pressure
correct during idle?
(See
FUEL LINE
PRESSURE
INSPECTION [LF]
.)
Yes
Inspect the ignition timing.
No
Low:
Inspect the fuel pump relay and
fuel pump circuit.
Inspect the fuel line for
clogging.
If there is no malfunction,
replace the fuel pump unit.
(See
FUEL PUMP UNIT
REMOVAL/INSTALLATION
[LF]
.)
High:
Replace the fuel pump unit.
(See
FUEL PUMP UNIT
REMOVAL/INSTALLATION
[LF]
.)
6
Inspect the knock
sensor.
Is the knock sensor
normal?
Yes
Inspect ignition timing.
No
Replace the knock sensor.
7
Verify test results.
If normal, return to diagnostic index to service any additional
symptoms.
(See
ENGINE SYMPTOM TROUBLESHOOTING [LF]
.)
If malfunction remains, inspect related Service Bulletins and/or On-
line Repair Information and perform repair or diagnosis.
If vehicle is repaired, troubleshooting completed.
If vehicle is not repaired or additional diagnostic information
is not available, replace the PCM.
(See
PCM REMOVAL/INSTALLATION [LF]
.)
14
POOR FUEL ECONOMY
DESCRIPTION
Fuel economy is unsatisfactory.
Contaminated air cleaner element
Variable intake air control malfunction
Engine cooling system malfunction
2007 Mazda MX-5 Miata Sport
2007 ENGINE PERFORMANCE Symptom Troubleshooting - MX-5 Miata
Microsoft
Thursday, July 09, 2009 2:42:10 PM
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