Mitsubishi Lancer Evolution X. Manual - part 271

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.
• MB991827: USB Cable
• MB991910: Main Harness A

• MB992110: Power Plant ECU Check Harness

STEP 1. Using scan tool MB991958, check data list item 8: 
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 

8, 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, 31 − 45 kPa (9.1 − 13.3 in.Hg).
• When the engine is suddenly revved, manifold absolute 

pressure varies.

(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 − How to 

Cope with Intermittent Malfunctions 

P.00-15

.

NO :  Go to Step 2.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 2. Measure the sensor output voltage at manifold 
absolute pressure sensor connector B-18 by backprobing.
(1) Do not disconnect the connector B-18.
(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 between 

1.2 and 1.8 volts.

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

between 1.1 and 1.7 volts.

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

between 1.0 and 1.6 volts.

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

between 0.9 and 1.5 volts.

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

YES : Go to Step 10.
NO :  Go to Step 3.

STEP 3. Measure the sensor supply voltage at manifold 
absolute pressure sensor connector B-18 by backprobing.
(1) Do not disconnect the connector B-18.
(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 4.9 and 5.1 volts.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.9 and 5.1 volts?

YES : Go to Step 6.
NO :  Go to Step 4.

STEP 4. Check harness connector B-18 at the manifold 
absolute pressure sensor and harness connector B-09 at 
ECM for damage.
Q: Is the harness connector in good condition?

YES : Go to step 5.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 13.

STEP 5. Check for harness damage between manifold 
absolute pressure sensor connector B-18 (terminal No. 3) 
and ECM connector B-09 (terminal No. 44).
Q: Is the harness wire in good condition?

YES : Go to Step 12.
NO :  Repair it. Then go to Step 13.

3

2

1

AK203034

B-18 harness 
connector: 
harness side

AM

3

2

1

AK203036

B-18 harness 
connector: 
harness side

AM

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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STEP 6. Measure the ground voltage at manifold absolute 
pressure sensor connector B-18 by backprobing.
(1) Do not disconnect the connector B-18.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 2 and ground by 

backprobing.

• Voltage should be 0.5 volt or less.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage 0.5 volt or less?

YES : Go to Step 9.
NO :  Go to Step 7.

STEP 7. Check harness connector B-18 at the manifold 
absolute pressure sensor and harness connector B-09 at 
ECM for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 8.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 13.

STEP 8. Check for harness damage between manifold 
absolute pressure sensor connector B-18 (terminal No. 2) 
and ECM connector B-09 (terminal No. 46).
Q: Is the harness wire in good condition?

YES : Go to Step 12.
NO :  Repair it. Then go to Step 13.

STEP 9. Check harness connector B-18 at manifold 
absolute pressure sensor for damage.
Q: Is the harness connector in good condition?

YES : Replace the manifold absolute pressure sensor. 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 10. Check harness connector B-18 at the manifold 
absolute pressure sensor and harness connector B-09 at 
ECM for damage.
Q: Is the harness connector in good condition?

YES : Go to Step 11.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 13.

3

2

1

AK203038

B-18 harness 
connector: 
harness side

AM

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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STEP 11. Measure the sensor output voltage at ECM 
connector B-09 by using power plant ECU check harness 
special tool MB992110.
(1) Disconnect all ECM connectors. Connect the power plant 

ECU check harness special tool MB992110 between the 
separated connectors.

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

(3) Measure the voltage between terminal No. 45 and ground.

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

1.2 and 1.8 volts.

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

between 1.1 and 1.7 volts.

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

between 1.0 and 1.6 volts.

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

between 0.9 and 1.5 volts.

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

YES : Go to Step 12.
NO :  Repair harness wire between manifold absolute 

pressure sensor connector B-18 (terminal No. 1) and 
ECM connector B-09 (terminal No. 45) because of 
harness damage. Then go to Step 13.

AK604040

ECM

AB

Body side harness 

MB992110

AK604177

16 15 14 13 12 11 10 9 8 7 6 5 4 3

2

1

32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17

48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33

64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49

AB

Power plant ECU
check harness connector