Mitsubishi Lancer Evolution IX. Manual — part 387

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-23

STEP 9. Check harness between B-28 (terminal
No. 2) fuel pressure control solenoid valve
connector and C-119 (terminal No. 48)
engine-ECU connector.

• Check output line for damage.

Q: Is the check result normal?

YES :

Go to Step 10 .

NO :

Repair the damaged harness wire.

STEP 10. Check harness between B-28 (terminal
No. 1) fuel pressure control solenoid valve
connector and B-12X (terminal No. 4) engine
control relay connector.

• Check power supply line for damage.

Q: Is the check result normal?

YES :

Go to Step 11 .

NO :

Repair the damaged harness wire.

STEP 11. M.U.T.-II/III actuator test

• Item No. 09: Fuel pressure control solenoid valve

OK: Operating sound can be heard and the
valve vibrates.

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use

Troubleshooting/Inspection Service Points

P.00-5

).

NO :

Replace the engine-ECU.

AK305002

1

2

AB

Connector : B-28

Harness side
connector

B-28(B)

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305002

1

2

AB

Connector : B-28

Harness side
connector

B-28(B)

AK305003

2

1

3

4

AB

Connector : B-12X

B-12X

Harness side
connector

Relay box’s
triangle marks

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-24

Code No. P0100: Air Flow Sensor System

1 2 3 4 5 6 7

1

2

3

4

AK501800

65

43
50

42
49

41
48
60 61

64

46 47
58 59
67 68

45

56
66

52

51

44

53

62

54

63

57

55

2

3 4

5 6

7 8

9

11 12 13 14 15 16 17 18 19 20

30

21 22 23

24 25

26 27 28 29

3132 33

34 35

1

10

5 V

B-105

(MU802552)

C-119

(MU803782)

C-121

(MU803783)

Engine control relay

Battery

Air flow sensor

19

7

34

61

4

5

3

L-B

B

B-Y

6 <A-13> (*1) or
13 <C-31> (*2)

R-Y

B-Y

B-Y

W-B

Wire colour code
B: Black LG: Light green G: Green L: Blue W: White Y: Yellow SB: Sky blue BR: Brown O: Orange GR: Gray
R: Red P: Pink V: Violet PU: Purple

Engine-ECU

2

1

3

4

B-12X

Air flow sensor circuit

AB

NOTE

*1: L.H. drive vehicles
*2: R.H. drive vehicles

To engine-ECU

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-25

OPERATION

• Power is supplied to the air flow sensor (terminal

No. 4) from the engine control relay (terminal No.
4) and earthed to the engine-ECU (terminal No.
34) from the air flow sensor (terminal No. 5).

• A power voltage of 5 V is applied to the air flow

sensor output terminal (terminal No. 3) from the
engine-ECU (terminal No. 61).

• An air flow sensor filter reset signal is inputted to

the air flow sensor (terminal No. 7) from the
engine-ECU (terminal No. 19).

FUNCTION

• Air flow sensor outputs a pulse signal propor-

tional to the intake air flow rate.

• The engine-ECU determines the basic injection

timing of the injector using the pulse signal output
from the air flow sensor and the engine speed
signal.

• When the throttle position sensor output is low,

the engine-ECU causes the power transistor in
the unit to be ON to send an air flow sensor filter
reset signal to the air flow sensor. In response to
the reset signal, the air flow sensor resets the fil-
ter circuit to improve the ability of the air flow sen-
sor to measure the air flow rate in the area where
the intake air flow rate is low.

TROUBLE JUDGMENT

Check Condition

• Engine speed of 500 r/min. or more.

Judgment Criterion

• The sensor output frequency of 3.3 Hz or more

for 2 seconds.

PROBABLE CAUSES

• Failed air flow sensor

• Open/short circuit in air flow sensor circuit or

loose connector contact

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-II/III data list

• Refer to Data List Reference Table

P.13A-372

.

a. Item No. 12: Air flow sensor

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Use

Troubleshooting/Inspection Service Points

P.00-5

).

NO :

Go to Step 2 .

STEP 2. Connector check: B-105 air flow sensor
connector

Q: Is the check result normal?

YES :

Go to Step 3 .

NO :

Repair or replace the connector.

STEP 3. Perform voltage measurement at B-105
air flow sensor connector.

• Disconnect connector, and measure at harness

side.

• Ignition switch: "ON"

• Voltage between terminal No. 3 and earth.

OK: 4.9

− 5.1 V

Q: Is the check result normal?

YES :

Go to Step 9 .

NO :

Go to Step 4 .

AK305005

3

4

5

1

2

6

7

AB

Connector : B-105

Harness side
connector

B-105(B)

AK305005

3

4

5

1

2

6

7

AB

Connector : B-105

Harness side
connector

B-105(B)

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-26

STEP 4. Perform voltage measurement at C-119
engine-ECU connector.

• Measure engine-ECU terminal voltage.

• Ignition switch: "ON"

• Voltage between terminal No. 61 and earth.

OK: 4.9

− 5.1 V

Q: Is the check result normal?

YES :

Go to Step 5 .

NO :

Go to Step 6 .

STEP 5. Connector check: C-119 engine-ECU
connector

Q: Is the check result normal?

YES :

Check and repair harness between B-105

(terminal No. 3) air flow sensor connector
and C-119 (terminal No. 61) engine-ECU
connector.

• Check output line for open circuit.

NO :

Repair or replace the connector.

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK501994

65

43
50

42
49

41
48
60

61

64

46

47

58

59

67

68

45

56
66

52 51

44

53

62

54

63

57

55

AB

Connector: C-119

C-119 (GR)

C-119 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305005

3

4

5

1

2

6

7

AB

Connector : B-105

Harness side
connector

B-105(B)