Mitsubishi Lancer Evolution IX. Manual - part 448

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-267

STEP 18. Check harness between ignition coil 
connector terminal No. 2 of each cylinder and 
body earth.

• Check earthing line for open circuit and damage.

Q: Is the check result normal?

YES : 

Check and repair harness between ignition 

coil connector terminal No. 3 of each 
cylinder and C-121 engine-ECU connector.

• Check signal line for open/short 

circuit and damage.

NO : 

Repair the damaged harness wire.

STEP 19. Check spray condition of injector.

• Check each injector for spray condition (Refer to 

P.13A-406

).

Q: Is the check result normal?

YES : 

Go to Step 20 .

NO : 

Replace the injector.

STEP 20. Check compression pressure.

• Check compression pressure (Refer to GROUP 

11A 

− On-vehicle Service 

P.11A-11

).

Q: Is the check result normal?

YES : 

Go to Step 21 .

NO : 

Repair.

STEP 21. Check EGR control solenoid valve 
itself.

• Check EGR control solenoid valve itself (Refer to 

GROUP 17 

− Emission Control System − 

Exhaust Gas Recirculation (EGR) System 

P.17-15

).

Q: Is the check result normal?

YES : 

Go to Step 22 .

NO : 

Replace the EGR control solenoid valve.

STEP 22. Check EGR valve itself.

• Check EGR valve itself (Refer to GROUP 17 − 

Emission Control System 

− Exhaust Gas Recir-

culation (EGR) System 

P.17-15

).

Q: Is the check result normal?

YES : 

Go to Step 23 .

NO : 

Replace the EGR valve.

STEP 23. Replace the engine-ECU.

• After replacing the engine-ECU, re-check the 

trouble symptoms.

Q: Does trouble symptom persist?

YES : 

Check for foreign matters (water, kerosene, 

etc.) in fuel and replace if necessary.

NO : 

The check is end.

AK305047

1

2

3

Connector : B-103, B-114

B-114(GR)

B-103(GR)

AB

Harness side 
connector

AK501995

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

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-268

Inspection Procedure 8: Unstable Idling (Rough Idling, hunting), Improper Idling Speed (Too High or 
too Low), Engine Stalls During Idling (Die Out)

COMMENTS ON TROUBLE SYMPTOM

• Probable causes can be widely found in ignition 

system, air-fuel ratio control system, idle speed 
control system, fuel system, etc. A sudden 
engine stall is possibly caused by poor connector 
contact.

PROBABLE CAUSES

• Failed ignition system

• Failed fuel system

• Failed air-fuel ratio control system

• Failed idle speed control system

• Failed intake/exhaust system

• Failed emission gas cleaning system

• Throttle valve body fouled

• Timing belt out of place

• Compression pressure improper

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check battery condition.

Q: Has the battery terminal been disconnected?

YES : 

After warm-up engine, idle for about 10 

minutes.

NO : 

Go to Step 2 .

STEP 2. M.U.T.-II/III diagnosis code

Q: Diagnosis code set?

YES : 

Inspection chart for diagnosis code (Refer 

to 

P.13A-17

).

NO : 

Go to Step 3 .

STEP 3. M.U.T.-II/III data list

• Refer to Data List Reference Table 

P.13A-372

.

a. Item No. 12: Air flow sensor
b. Item No. 13: Intake air temperature sensor 

c. Item No. 14: Throttle position sensor

d. Item No. 21: Engine coolant temperature sen-

sor 

e. Item No. 25: Barometric pressure sensor

Q: Are the check results normal?

YES : 

Go to Step 4 .

NO : 

Perform the diagnosis code classified check 
Procedure for the sensor that has shown an 
abnormal data value (Refer to Inspection 
Chart for Diagnosis Codes 

P.13A-17

).

STEP 4. M.U.T.-II/III data list

• Refer to Data List Reference Table 

P.13A-372

.

a. Item 27: Power steering fluid pressure switch

Q: Is the check result normal?

YES : 

Go to Step 5 .

NO : 

Check power steering fluid pressure switch 
system (Refer to Code No. P0551 

P.13A-197

).

STEP 5. Check idle speed control servo for 
operating sound.

• Check idle speed control servo for operating 

sound (Refer to 

P.13A-408

).

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Check idle speed control servo system 
(Refer to Code No. P0505 

P.13A-190

).

STEP 6. Check throttle body (throttle valve 
portion) for contamination.

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Clean throttle body (throttle valve portion) 
(Refer to 

P.13A-395

).

STEP 7. Check air intake from intake hose and 
intake manifold.

Q: Is the check result normal?

YES : 

Go to Step 8 .

NO : 

Repair.

STEP 8. Check injector for operating sound.

• Check injector for operating sound (Refer to 

P.13A-406

).

Q: Can operating sound be heard?

YES : 

Go to Step 9 .

NO : 

Check the injector system of the defective 

cylinder.

(Refer to Code No. P0201: No. 1 injector 

system 

P.13A-105

).

(Refer to Code No. P0202: No. 2 injector 

system 

P.13A-111

).

(Refer to Code No. P0203: No. 3 injector 

system 

P.13A-117

).

(Refer to Code No. P0204: No. 4 injector 

system 

P.13A-123

).

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-269

STEP 9. Check timing marks of timing belt.

Q: Is the check result normal?

YES : 

Go to Step 10 .

NO : 

Align timing marks.

STEP 10. M.U.T.-II/III data list

• Refer to Data List Reference Table 

P.13A-372

.

a. Item No. 11: Oxygen sensor (front)

Q: Is the check result normal?

YES : 

Go to Step 11 .

NO : 

Check the oxygen sensor (front) system

(Refer to Code No. P0130 

P.13A-75

).

STEP 11. Perform voltage measurement at C-119 
engine-ECU.

• Measure engine-ECU terminal voltage.

• Ignition switch: "ON"

• Voltage between terminal No. 46 and earth, also 

between terminal No. 58 and earth.

OK: 0.5 V or less

Q: Is the check result normal?

YES : 

Go to Step 13 .

NO : 

Go to Step 12 .

STEP 12. Connector check: C-119 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Check and repair harness between C-119 

(terminal No. 46 and No. 58) engine-ECU 
connector and body earth.

• Check earthing line for open circuit 

and damage.

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>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-270

STEP 13. Perform voltage measurement at C-121 
engine-ECU connector.

• Measure engine-ECU terminal voltage.

• Engine: Idling after warm-up

• Transmission: Neutral

• Radiator fan: Not operating

• Voltage between terminal No. 8 and earth.

OK: Switching the head lamps to ON from 
OFF causes the voltage to increase by 0.2 

− 

3.5 V.

Q: Is the check result normal?

YES : 

Go to Step 16 .

NO : 

Go to Step 14 .

STEP 14. Connector check: C-121 engine-ECU 
connector and B-25 alternator connector.

Q: Is the check result normal?

YES : 

Go to Step 19 .

NO : 

Repair or replace the connector.

AK501995

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

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK501995

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

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305036

M

2

1

3

4

Harness side 
connector

AB

Connector : B-25

B-25(GR)