Mitsubishi 3000GT Service Manual page 144

MULTIPORT FUEL INJECTION - Troubleshootina
DTC No.
PO1 25
Excessive Time to Enter Closed Loop Fuel Control
Background
The MFI system reduces exhaust emissions by means of closed-loop fuel control.
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The engine control module checks the time taken until closed-loop fuel control commences.
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Range of Check, Set Conditions
Even though the specified length of time (approximately 30 seconds) has passed since the
conditions* were met following starting of the engine, the MFI system does not enter closed-loop
fuel control.
temperature of 20-50°C (68-122'F), an engine speed of 1,900-2,200 r/min., etc.
When the oxygen sensor begins to deteriorate, the oxygen sensor signal response becomes
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The engine control module forcibly varies the air-fuel mixture to make it leaner and richer,
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and checks the response speed of oxygen sensor.
In addition, the engine control module also checks for an open circuit in the oxygen sensor
Oxygen Sensor Heater Circuit Malfunction (Bank 1
Sensor 1)
Background
The engine control module checks whether the heater current is within a specified range when
the heater is energized.
Range of Check, Set Conditions
The oxygen sensor heater current is either lower than several dozen milliamperes or higherthan
several amperes.
DTC No.
PO1 36 Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2)
Background
The engine control module checks for an open circuit in the heatd oxygen sensor output line.
Range of Check, Set Conditions
The heated oxygen sensor output line is open-circuit.
Title
when the amount of fuel injected is increased
ontrol of the air-fuel ratio.
Title
TSB Revision
Probable causes
Heated oxygen sensor failed.
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Injector failed.
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Engine control module failed.
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Probable causes
circuit in oxygen sensor
e control module failed.
Probable causes
Open or shorted oxygen sensor
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heater circuit.
Open circuit in oxygen sensor
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heater.
Engine control module failed.
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Probable causes
Heated oxygen sensor failed.
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Engine control module failed.
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Open circuit in heated oxygen
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sensor output line.