Mitsubishi Lancer Evolution IX. Manual - part 415

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-135

Code No. P0300: Random Cylinder Misfire Detected

OPERATION

• Refer to P0201 injector circuit 

P.13A-105

.

• Refer to P0202 injector circuit 

P.13A-111

.

• Refer to P0203 injector circuit 

P.13A-117

.

• Refer to P0204 injector circuit 

P.13A-123

.

FUNCTION

• If a misfire occurs while the engine is running, the 

engine speed changes for an instant.

• The engine-ECU checks for such changes in 

engine speed.

TROUBLE JUDGMENT

Check Conditions

• The engine speed is 500 − 6,500 r/min.

• The engine coolant temperature is −10°C or 

higher.

• The barometric pressure is 76 kPa or more.

• The volumetric efficiency is 30 − 55%.

• The adaptive learning has been completed with 

the vane that generates the crankshaft position 
signals.

• During the engine operation except the shift 

change or low speed driving and rapid accelera-
tion and deceleration, also intermittent operation 
of air compressor (A/C: within the 3 seconds after 
changing to ON from OFF or to OFF from ON).

• The throttle deviation is within the range of −0.06 

V/10ms to 0.06 V/10ms.

Judgment Criteria

• Misfire has occurred more frequently than 

allowed during the last 200 revolutions (When the 
catalyst temperature is higher than 950

°C).

or

• Misfire has occurred in 15 or more of the last 

1,000 revolutions (corresponding to 1.5 times the 
limit of emission standard).

PROBABLE CAUSES

• Ignition system related part(s) failed

• Failed crank angle sensor

• Incorrect air-fuel ratio

• Low compression pressure

• Failed coolant temperature sensor

• Skipping of timing belt teeth.

• EGR system and EGR valve failed

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-II/III data list 

• Item No. 22: Crank angle sensor

OK: Keep the engine speed constant to make 
the pulse width of output waveform con-
stant.

Q: Is the check result normal?

YES : 

Go to Step 2 .

NO : 

Check crank angle sensor system (Refer to 
Code No. P0335 

P.13A-155

).

STEP 2. M.U.T.-II/III data list

• Refer to Data List Reference Table 

P.13A-372

.

a. Item No. 21: Engine coolant temperature sensor
b. Item No. 81: Long-term fuel compensation

c. Item No. 82: Short-term fuel compensation

Q: Are the check results normal?

YES : 

Go to Step 3 .

NO : 

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

P.13A-17

).

STEP 3. Check ignition coil spark.

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Check ignition circuit system (Refer to 
Inspection procedure 30 <L.H. drive 
vehicles>

P.13A-356

 or Inspection 

procedure 31 <R.H. drive 
vehicles>

P.13A-363

).

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-136

STEP 4. Connector check: Injector connector

a. B-22 (No. 1 injector connector)
b. B-20 (No. 2 injector connector)

c. B-18 (No. 3 injector connector)

d. B-17 (No. 4 injector connector)

Q: Are the check results normal?

YES : 

Go to Step 5 .

NO : 

Repair or replace the connector.

STEP 5. Check injector itself. 

• Check Injector itself (Refer to 

P.13A-406

).

Q: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Replace the injector.

STEP 6. Connector check: C-121 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Repair or replace the connector.

AK305012

1

2

Connector : B-17,B-18,B-20,B-22

Harness side connector

B-22(B) B-20(B) B-18(B) B-17(B)

AB

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-137

STEP 7. Check harness between injector 
connector and C-121 engine-ECU connector.

a. Check harness between B-22 (terminal No. 2) 

No. 1 injector connector and C-121 (terminal No. 
1) engine-ECU connector.

b. Check harness between B-20 (terminal No. 2) 

No. 2 injector connector and C-121 (terminal No. 
9) engine-ECU connector.

c. Check harness between B-18 (terminal No. 2) 

No. 3 injector connector and C-121 (terminal No. 
24) engine-ECU connector.

d. Check harness between B-17 (terminal No. 2) 

No. 4 injector connector and C-121 (terminal No. 
2) engine-ECU connector.

• Check output line for damage.

Q: Are the check results normal?

YES : 

Go to Step 8 .

NO : 

Repair the damaged harness wire.

STEP 8. Check injector resistor itself.

• Check injector resistor itself (Refer to 

P.13A-407

).

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Replace the injector resistor.

AK305012

1

2

Connector : B-17,B-18,B-20,B-22

Harness side connector

B-22(B) B-20(B) B-18(B) B-17(B)

AB

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-138

STEP 9. Connector check: B-119 injector resistor 
connector and C-121 engine-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 10 .

NO : 

Repair or replace the connector.

STEP 10. Check harness between B-119 injector 
resistor connector and injector connector.

a. Check harness between B-119 (terminal No. 1) 

injector resistor connector and B-22 (terminal No. 
1) No. 1 injector connector.

b. Check harness between B-119 (terminal No. 4) 

injector resistor connector and B-20 (terminal No. 
1) No. 2 injector connector.

c. Check harness between B-119 (terminal No. 5) 

injector resistor connector and B-18 (terminal No. 
1) No. 3 injector connector.

d. Check harness between B-119 (terminal No. 6) 

injector resistor connector and B-17 (terminal No. 
1) No. 4 injector connector.

• Check output line for damage.

Q: Are the check results normal?

YES : 

Go to Step 11 .

NO : 

Repair the damaged harness wire.

AK305016

1

2

3

4

5

6

AB

Harness side 
connector

B-119(B)

B-119(B)

Connector : B-119

<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>

AK305016

1

2

3

4

5

6

AB

Harness side 
connector

B-119(B)

B-119(B)

Connector : B-119

<L.H.drive vehicles>

<R.H.drive vehicles>

AK305012

1

2

Connector : B-17,B-18,B-20,B-22

Harness side connector

B-22(B) B-20(B) B-18(B) B-17(B)

AB