Mitsubishi Eclipse. Manual — part 452

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-351

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CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the ECM (ter-
minal No. 71) <M/T> or PCM (terminal No. 71)
<A/T> from the output terminal (terminal No. 4) of
the left bank heated oxygen sensor (front).

• Terminal No. 2 of the left bank heated oxygen

sensor (front) is grounded with ECM (terminal
No. 49) <M/T> or PCM (terminal No. 57) <A/T>.

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TECHNICAL DESCRIPTION

• The left bank heated oxygen sensor (front)

detects the concentration of oxygen in the
exhaust gas; it converts that data to voltage, and
sends it to the ECM <M/T> or PCM <A/T>.

• When the left bank heated oxygen sensor (front)

begins to deteriorate, the heated oxygen sensor
signal response deteriorates also.

• The ECM <M/T> or PCM <A/T> varies the air/fuel

mixture to make it leaner and richer, and checks
the response speed of the left bank heated oxy-
gen sensor (front). In addition, the ECM <M/T> or
PCM <A/T> also checks for an open circuit in the
left bank heated oxygen sensor (front) output
line.

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DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor (front) output volt-

age stays low when air/fuel ratio is forced to be
rich. The above procedure is repeated when oxy-
gen sensor is inactive.

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MONITOR EXECUTION
Continuous

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MONITOR EXECUTION CONDITIONS (Other
monitor and Sensor)

Other Monitor (There is no temporary DTC stored

in memory for the item monitored below)

• Heated oxygen sensor heater (front) monitor

• Misfire monitor

• Fuel system monitor

Sensor (The sensor below is determined to be

normal)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

• Throttle position sensor

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AK300061

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-24

AB

B-24 (B)

AK300091

CONNECTORS: C-58, C-62 <M/T>

ECM

AD

C-58 (GR)

C-62 (GR)

AK300244

CONNECTORS: C-55, C-59 <A/T>

AD

PCM

C-55 (GR)

C-59 (GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-352

DTC SET CONDITIONS

Logic Flow Chart

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Check Conditions

• 3 minutes or more have passed since the starting

sequence was completed.

• Left bank heated oxygen sensor (front) signal

voltage has continued to be 0.2 volt or lower.

• Engine coolant temperature is higher than 76°C

(169

°F).

• Engine speed is higher than 1,200 r/min.

• Volumetric efficiency is higher than 25 percent.

• Volume airflow sensor output frequency is 75 Hz

or more.

START

V

F

> =4.5V

2secs HAS PASSED

YES

YES

YES

NO

NO

NO

MALFUNCTION

MONITORING

CONDITIONS

YES

NO

MONITORING

CONDITIONS

+5V ON

AK301436

V

F

< 0.2V

10secs HAS PASSED

YES

YES

NO

NO

END

MALFUNCTION

GOOD

MODULATE A/F CONDITION TO RICH

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-353

• At least 20 seconds have passed since fuel shut

off control was canceled.

• Monitoring time: 10 seconds.

Judgement Criteria

• Making the air/fuel ratio 15 percent for 10 sec-

onds richer does not result in raising the heated
oxygen sensor (front) output voltage beyond 0.15
volt.

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OBD-ll DRIVE CYCLE PATTERN
Refer to , Diagnostic Function

− OBD-ll Drive Cycle −

Procedure 6

− Other Monitor

P.13B-7

.

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TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are: )

• Left bank heated oxygen sensor (front) failed.

• Short circuit in left bank heated oxygen sensor

(front) output line.

• ECM failed. <M/T>

• PCM failed. <A/T>

• Connector damage.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

• MD998464: Test Harness

STEP 1. Using scan tool MB991958, check data list item 11:
Heated Oxygen Sensor Bank 2, Sensor 1 (left front).

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine and run at idle.
(3) Set scan tool MB991958 to the data reading mode for item

11, Heated Oxygen Sensor Bank 2, Sensor 1 (left front).

• Warming up the engine. When the engine is revved, the

output voltage should be 0.6 to 1.0 volt.

• Warming up the engine. When the engine is idling, the

output voltage should repeat 0.4 volt and 0.6 to 1.0 volt
alternately.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent.

Refer to GROUP 00, How to Use Troubleshooting/
Inspection Service Points

P.00-6

.

NO : Go to Step 2.

AK300810

AB

MB991911

16-PIN

MB991827

MB991824

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI) <3.0L>

13B-354

STEP 2. Check the left bank heated oxygen sensor (front).
(1) Disconnect the left bank heated oxygen sensor (front)

connector B-24 and connect test harness special tool,
MD998464, to the connector on the left bank heated oxygen
sensor (front) side.

(2) Warm up the engine until engine coolant 80

°C (176°F) or

higher.

CAUTION

Be very careful when connecting the jumper wires; incor-
rect connection can damage the right bank heated oxygen
sensor (front).

(3) Use the jumper wires to connect terminal 1 (red clip) to the

positive battery terminal and terminal 3 (blue clip) to the
negative battery terminal.

(4) Connect a digital volt meter between terminal 2 (black clip)

and terminal 4 (white clip).

(5) While repeatedly revving the engine, measure the left bank

heated oxygen sensor (front) output voltage.

Standard value: 0.6

− 1.0 volt

Q: Is the voltage between 0.6 and 1.0 volt?

YES : Go to Step 3.
NO : Replace the left bank heated oxygen sensor (front).

Then go to Step 5.

AK300424

1

2

3

4

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

CONNECTOR: B-24

AB

B-24 (B)

HARNESS CONNECTOR:
COMPONENT SIDE

AKX01625AC

BLUE

RED

BLACK

JUMPER
WIRES

WHITE

MD998464