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Mitsubishi Montero (2004+). Manual - part 139

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-43

CIRCUIT OPERATION

• The volume airflow sensor power is supplied from

the MFI relay (terminal No. 1), and the ground is
provided on the PCM (terminal No. 88).

• 5-volt power is applied to the volume airflow sen-

sor output terminal (terminal No. 3) from the PCM
(terminal No. 63). The volume airflow sensor gen-
erates a pulse signal when the output terminal
and ground are opened/closed (opened/short).

TECHNICAL DESCRIPTION

• While the engine is running, the volume airflow

sensor outputs a pulse signal which corresponds
to the volume of air flow.

• The PCM checks whether the frequency of this

signal output by the volume airflow sensor while
the engine is running is at or above the set value.

DESCRIPTIONS OF MONITOR METHODS

• An open or short circuit is detected while monitor-

ing the output frequency of the volume airflow
sensor.

MONITOR EXECUTION

• Continuous

MONITOR EXECUTION CONDITIONS (Other
monitor and Sensor)

Other Monitor (There is no temporary DTC stored

in memory for the item monitored below)

• Not applicable

Sensor (The sensor below is determined to be

normal)

• Not applicable

AK201039

MFI RELAY

B-22X

CONNECTOR: B-22X

AK200940AD

B-48(B)

CONNECTOR: B-48

VOLUME AIRFLOW
SENSOR

AK201038AH

CONNECTORS: D-133, D-134

PCM

D-134(GR)

D-133(GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-44

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

• Engine speed is higher than 500 r/min.

Judgement Criteria

• Volume airflow sensor output frequency has con-

tinued to be 3.3 Hz or lower for 2 seconds.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function

− OBD-II Drive Cycle −

Procedure 6

− Other Monitor

P.13A-4

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

• Volume airflow sensor failed.

• Open or shorted volume airflow sensor circuit,

harness damage, or 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

START

MONITORING
CONDITIONS

END

YES

MALFUNCTION

GOOD

OUTPUT FREQUENCY

< 3.3Hz

CONTINUOUS

FAILURE FOR 2 secs

AK302919

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-45

STEP 1. Using scan tool MB991958, check data list item 12:
Volume Airflow Sensor.

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

12, Volume Airflow Sensor.

(4) Warm up the engine to normal operating temperature: 80

°C

to 95

°C (176°F to 203°F).

• The standard value during idling should be 10 Hz or

more.

• When the engine is revved, the frequency should

increase according to the increase in engine speed.

(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.00-6

NO : Go to Step 2.

STEP 2. Measure the power supply voltage at volume
airflow sensor connector B-48 by backprobing.
(1) Do not disconnect the connector B-48.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No.4 and ground by

backprobing.

• Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts)

present?
YES : Go to Step 5.
NO : Go to Step 3.

AK302970

MB991911

MB991824

MB991827

AK200937

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-48

B-48(B)

AKX01514

6 7

1 2 3 4 5

AKX01514

B-48 HARNESS
CONNECTOR:
HARNESS SIDE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-46

STEP 3. Measure the power supply voltage at volume
airflow sensor harness side connector B-48.
(1) Disconnect the connector B-48 and measure at the harness

side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 4 and ground.

• Voltage should be battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts)

present?
YES : Go to Step 4.
NO : Repair harness wire between MFI relay connector

B-22X (terminal No. 1) and volume airflow sensor
connector B-48 (terminal No. 4) because of open
circuit or short circuit to ground. Then go to Step 13.

STEP 4. Check connector B-48 at the volume airflow
sensor for damage.
Q: Is the connector in good condition?

YES : Repair harness wire between MFI relay connector

B-22X (terminal No. 1) and volume airflow sensor
connector B-48 (terminal No. 4) because of harness
damage. Then go to Step 13.

NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 13.

STEP 5. Check connector B-48 at volume airflow sensor
for damage.
Q: Is the connector in good condition?

YES : Go to Step 6.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then go to Step 13.

AK200937

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-48

B-48(B)

AKX01405

B-48 HARNESS CONNECTOR:
COMPONENT SIDE

AK200937

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-48

B-48(B)

AK200937

HARNESS
CONNECTOR:
COMPONENT SIDE

CONNECTOR: B-48

B-48(B)

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