Mitsubishi Lancer Evolution X. Manual - part 273

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-157

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.

STEP 2. 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 8.
NO :  Go to Step 3.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

3

2

1

AK203036

B-18 harness 
connector: 
harness side

AM

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 3. Check harness connector B-09 at ECM for 
damage.
Q: Is the harness 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.

STEP 4. Measure the sensor supply 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. 44 and ground.

• 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 7.
NO :  Go to Step 5.

STEP 5. Check harness connector B-18 at the manifold 
absolute pressure sensor for damage.
Q: Is the harness 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 12.

AK604040

ECM

AB

Body side harness 

MB992110

AK604178

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

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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STEP 6. Check for short circuit to ground 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 11.
NO :  Repair it. Then go to Step 12.

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

YES : Repair harness wire between manifold absolute 

pressure sensor connector B-18 (terminal No. 3) and 
ECM connector B-09 (terminal No. 44) because of 
open circuit. Then go to Step 12.

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

Connector Inspection 

P.00E-2

. Then go to Step 12.

STEP 8. 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 9.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 12.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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STEP 9. 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 11.
NO :  Go to Step 10.

STEP 10. Check for open circuit and short circuit to 
ground between manifold absolute pressure sensor 
connector B-18 (terminal No. 1) and ECM connector B-09 
(terminal No. 45).
Q: Is the harness wire in good condition?

YES : Replace the manifold absolute pressure sensor. Then 

go to Step 12.

NO :  Repair it. Then go to Step 12.

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