Mitsubishi Montero (2004+). Manual - part 150

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-87

DIAGNOSIS

Required Special Tools:

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

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

STEP 1. Using scan tool MB991958, check data list item 95: 
Manifold Absolute Pressure 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) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958 to the data reading mode for item 

95, Manifold Absolute Pressure Sensor.

• When altitude is 0 m (0 foot), 101 kPa (29.8 in.Hg).

• When altitude is 600 m (1,969 feet), 95 kPa (28.1 in.Hg).

• When altitude is 1,200 m (3,937 feet), 88 kPa (26.0 

in.Hg).

• When altitude is 1,800 m (5,906 feet), 81 kPa (23.9 

in.Hg).

(4) Start the engine.

• When the engine is idling, 16 − 36 kPa (4.7 − 10.6 

in.Hg).

• When the engine is suddenly revved, manifold absolute 

pressure increases.

(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.

AK302970

AB

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-88

STEP 2. Measure the sensor output voltage at manifold 
absolute pressure sensor connector B-28 by backprobing.
(1) Do not disconnect the connector B-28.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 1 and ground by 

backprobing.

• When altitude is 0 m (0 foot), voltage should be 3.7 and 

4.3 volts.

• When altitude is 600 m (1,969 feet), voltage should be 

3.4 and 4.0 volts.

• When altitude is 1,200 m (3,937 feet), voltage should be 

3.2 and 3.8 volts.

• When altitude is 1,800 m (5,906 feet), voltage should be 

2.9 and 3.5 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?

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

AK200975

1

2

3

AB

HARNESS 
CONNECTOR: 
COMPONENT SIDE

CONNECTOR: B-28

B-28(B)

3

2

1

AK203034

B-28 HARNESS 
CONNECTOR: 
HARNESS SIDE

AI

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-89

STEP 3. Check connector B-28 at the manifold absolute 
pressure sensor and connector D-135 at PCM for damage.
Q: Is the connector in good condition?

YES : Go to Step 4.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

AK200975

1

2

3

AB

HARNESS 
CONNECTOR: 
COMPONENT SIDE

CONNECTOR: B-28

B-28(B)

AK200947

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

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120

CONNECTOR: D-135

HARNESS CONNECTOR: 
COMPONENT SIDE

AB

PCM

D-135(GR)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-90

STEP 4. Using scan tool MB991958, check data list item 95: 
Manifold Absolute Pressure 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) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958 to the data reading mode for item 

95, Manifold Absolute Pressure Sensor.

• When altitude is 0 m (0 foot), 101 kPa (29.8 in.Hg).

• When altitude is 600 m (1,969 feet), 95 kPa (28.1 in.Hg).

• When altitude is 1,200 m (3,937 feet), 88 kPa (26.0 

in.Hg).

• When altitude is 1,800 m (5,906 feet), 81 kPa (23.9 

in.Hg).

(4) Start the engine.

• When the engine is idling, 16 − 36 kPa (4.7 − 10.6 

in.Hg).

• When the engine is suddenly revved, manifold absolute 

pressure increases.

(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 :  Replace the PCM. Then go to Step 12.

STEP 5. Measure the sensor supply voltage at manifold 
absolute pressure sensor connector B-28 by backprobing.
(1) Do not disconnect the connector B-28.
(2) Turn the ignition switch to the "ON" position.

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

backprobing.

• Voltage should be between 4.8 and 5.2 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.8 and 5.2 volts?

YES : Go to Step 7.
NO :  Go to Step 6.

AK302970

AB

MB991911

MB991824

MB991827

AK200975

1

2

3

AB

HARNESS 
CONNECTOR: 
COMPONENT SIDE

CONNECTOR: B-28

B-28(B)

3

2

1

AK203036

B-28 HARNESS
CONNECTOR:
HARNESS SIDE

AI