Mitsubishi Montero Sport (2004+). Manual - part 222

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-301

CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 71) 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 PCM (terminal
No. 57).

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
inputs the resulting signals to the PCM.

• When the left bank heated oxygen sensor (front)

begins to deteriorate, the heated oxygen sensor
signal response becomes poor.

• The PCM varies the air/fuel mixture to make it

leaner and richer, and checks the response
speed of the left bank heated oxygen sensor
(front). In addition, the PCM also checks for an
open circuit in the left bank heated oxygen sensor
(front) output line.

DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor (front) rich/lean

switching frequency is under specified value.

MONITOR EXECUTION
Continuous

AK200495

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

A-09(GR)

CONNECTOR: A-09

AK103912AB

CONNECTOR: C-71

C-71

AK103738AE

CONNECTORS: C-90, C-91

PCM

C-91(GR)

C-90(GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-302

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

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• Engine coolant temperature is higher than 50°C

(122

°F).

• Engine speed is at between 1,250 and 3,000

r/min.

• Volumetric efficiency is at between 25 and 60

percent.

• Under the closed loop air/fuel control.

• The throttle valve is open.

• short-term fuel trim is higher than −30 and +25

percent.

• More than 3 seconds have elapsed after the

abovementioned conditions have been met.

• The PCM monitors for this condition for 7 cycles

of 12 seconds each during the drive cycle.

F1: THRESHOLD VALUE FOR REAL-TIME SWITDHING FREQUENCY
F0: THRESHOLD VALUE FOR AVERAGE SWITDHING FREQUENCY

START

MONITORING

CONDITIONS

MALFUNCTION

GOOD

END

YES

Ff < F0

CALCULATE AVERAGE SWITCHING

FREQUENCY (Ff) OVER SPECIFIED TIMES

AK301438

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-303

Judgment Criteria

• The left bank heated oxygen sensor (front) sends

"lean" and "rich" signals alternately 11 times or
less for 12 seconds.
NOTE: If the sensor switch time is longer than the
Judgment Criteria due to the MUT-III OBD-II test
Mode

−

H02S Test Results, it is assumed that the

heated oxygen sensor has deteriorated. If it is
short, it is assumed that the harness wire is bro-
ken or has a short circuit.
If the heated oxygen sensor signal voltage has
not changed even once (lean/rich) after the DTC
was erased, the sensor switch time will display as
0 seconds.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 4

− Heated Oxygen Sensor Monitor

P.13A-4

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

• Left bank heated oxygen sensor (front) deterio-

rated.

• Connector damage.

• PCM failed.

DIAGNOSIS

Required Special Tools:

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

• MB991824: V.C.I

• MB991827: USB Cable

• MB991911: Main Harness B

• MB991316h: 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).

(4) Warm up the engine, 2,500 r/min.

• Output voltage repeats 0.4 volt or less and 0.6 − 1.0 volt

10 times or more within 10 seconds.

(5) 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.00-7

NO : Go to Step 2.

AK303629AB

MB991911

MB991827

MB991824

16-PIN

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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

connector A-09 and connect test harness special tool,
MB991316, 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.

(3) Perform a tracing for 5 minutes or more with the engine

speed of 4,500 r/min.

(4) Connect a digital volt meter between terminal No. 2 (black

clip) and terminal No. 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

CAUTION

• Be very careful when connecting the jumper wire;

incorrect connection can damage the oxygen sensor.

• Be careful the heater is broken when voltage of beyond

8 volts is applied to the oxygen sensor heater.
NOTE: If the sufficiently high temperature (of approximate
400

C or more) is not reached although the oxygen sensor

is normal, the output voltage would be possibly low
although the rich air-fuel ratio. Therefore, if the output volt-
age is low, use a jumper wire to connect the terminal No.1
(red clip of special tool) and the terminal No. 3 (blue clip of
special tool) of the oxygen sensor with a (+) terminal and (-)
terminal of 8 volts power supply respectively, then check
again.

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 4.

AK200496

A-09(GR)

CONNECTOR: A-09

HARNESS
CONNECTOR:
COMPONENT SIDE

LEFT BANK
HEATED OXYGEN
SENSOR (FRONT)

AKX01624

HEATED
OXYGEN
SENSOR
COMPONENT
SIDE
CONNECTOR

MB991316

WHITE

BLACK

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