Mitsubishi Lancer Evolution IX. Manual - part 418

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-147

STEP 7. Connector check: B-119 injector resistor 
connector and C-121 engine-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 8 .

NO : 

Repair or replace the connector.

STEP 8. Check harness between B-119 (terminal 
No. 5) injector resistor connector and B-18 
(terminal No. 1) No.3 injector connector.

• Check output line for damage.

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Repair the damaged harness wire.

STEP 9. Fuel pressure measurement.

• Fuel pressure measurement (Refer to fuel pres-

sure test 

P.13A-396

).

Q: Is the check result normal?

YES : 

Replace the engine-ECU.

NO : 

Repair.

AK305016

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AB

Harness side 
connector

B-119(B)

B-119(B)

Connector : B-119

<L.H.drive vehicles>

<R.H.drive vehicles>

AK501995

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AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305016

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AB

Harness side 
connector

B-119(B)

B-119(B)

Connector : B-119

<L.H.drive vehicles>

<R.H.drive vehicles>

AK305012

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2

Connector : B-18

Harness side connector

B-18(B)

AE

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-148

Code No. P0304: No. 4 Cylinder Misfire Detection System

OPERATION

• 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

• Low compression pressure

• Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the ignition coil spark.

Q: Is the check result normal?

YES : 

Go to Step 2 .

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

).

STEP 2. Connector check: B-17 No. 4 injector 
connector

Q: Is the check result normal?

YES : 

Go to Step 3 .

NO : 

Repair or replace the connector.

STEP 3. Check No. 4 injector itself.

• Check Injector itself (Refer to 

P.13A-406

).

Q: Is the check result normal?

YES : 

Go to Step 4 .

NO : 

Replace the No. 4 injector.

AK305012

1

2

Connector : B-17

Harness side connector

B-17(B)

AF

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-149

STEP 4. Connector check: C-121 engine-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 5 .

NO : 

Repair or replace the connector.

STEP 5. 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: Is the check result normal?

YES : 

Go to Step 6 .

NO : 

Repair the damaged harness wire.

STEP 6. Check injector resistor itself.

• Check injector resistor itself (Refer to 

P.13A-407

).

Q: Is the check result normal?

YES : 

Go to Step 7 .

NO : 

Replace the injector resistor.

AK501995

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AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305012

1

2

Connector : B-17

Harness side connector

B-17(B)

AF

AK501995

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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-150

STEP 7. Connector check: B-119 injector resistor 
connector and C-121 engine-ECU connector

Q: Is the check result normal?

YES : 

Go to Step 8 .

NO : 

Repair or replace the connector.

STEP 8. Check harness between B-119 (terminal 
No. 6) injector resistor connector and B-18 
(terminal No. 1) No. 4 injector connector.

• Check output line for damage.

Q: Is the check result normal?

YES : 

Go to Step 9 .

NO : 

Repair the damaged harness wire.

STEP 9. Fuel pressure measurement.

• Fuel pressure measurement (Refer to fuel pres-

sure test 

P.13A-396

).

Q: Is the check result normal?

YES : 

Replace the engine-ECU.

NO : 

Repair.

AK305016

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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

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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-18

Harness side connector

B-18(B)

AE