Mazda RX-8 Manual page 152

NO.14 POOR FUEL ECONOMY
14 POOR FUEL ECONOMY
The fuel economy is unsatisfactory.
DESCRIPTION
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POSSIBLE
CAUSE
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WARNING:
repair procedures. Read the following warnings before servicing fuel system:
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Contaminated air cleaner element
Air suction at intake-air system (between MAF sensor and intake ports)
Poor fuel quality
Inadequate fuel pressure
Pressure regulator (integrated in fuel pump unit) malfunction
Fuel pump relay stuck closed
Fuel leakage from fuel injector
Restriction in exhaust system
Erratic signal from eccentric shaft position sensor
Improper MAF sensor installation
Improper fuel injector control operation (abnormal signals from MAF, ECT,
front/rear HO2S and IAT sensors to PCM)
Knock sensor malfunction (abnormal signal to PCM)
Contaminated MAF sensor
Improper engine compression
Engine internal malfunction
Abnormal engine oil condition (viscosity, deterioration)
Low oil pressure
Excessive fuel pressure
Metering oil pump malfunction
Leakage or clogging in oil pipe
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Leakage or clogging in oil nozzle
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Eccentric shaft bypass valve malfunction (stuck open)
Improper cooling fan control system operation
Thermostat malfunction (stuck open)
Improper engine coolant level
Improper ignition timing
Weak spark
Spark plug malfunction
Brake dragging
Low tire pressure
Clutch slippage (MT)
Improper ATF level (AT)
Improper A/C operation (A/C cut-off control does not operate)
The following troubleshooting flow chart contains fuel system diagnosis and
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
(w) RX8-Engine Troubleshooting
Page 103