Mitsubishi 380. Manual - part 627

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-600

INSPECTION PROCEDURE 22: Too high CO and HC concentration when idling

.

COMMENT

• Abnormal air/fuel ratio is suspected.

.

TROUBLESHOOTING HINTS (The most 
likely causes for this case:)

• Malfunction of air/fuel ratio control system.

• Deteriorated catalyst.

• Refer to component locations GROUP-

70

• Refer to configuration diagrams GROUP-

80

• Refer to circuit diagrams GROUP-

90

DIAGNOSIS

Required Special Tools:

• Diagnostic tool(MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

STEP 1. Using diagnostic tool, read the diagnostic trouble 
code (DTC).

CAUTION

To prevent damage to diagnostic tool, always turn the igni-
tion switch to the "LOCK" (OFF) position before connect-
ing or disconnecting diagnostic tool.
(1) Connect diagnostic tool to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the DTC set?

YES : Refer to Diagnostic Trouble Code Chart 

P.13A-17

.

NO :  Go to Step 2.

STEP 2. Check the advance ignition timing.
Ignition timing is controlled by the ENGIN-ECUand will vary 
depending on engine requirement..

Q: Is the advance ignition timing normal?

YES : Go to Step 3.
NO :  Check that the crankshaft position sensor and timing 

belt cover are in the correct position. Then confirm 
that the malfunction symptom is eliminated. 

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-601

STEP 3. Using diagnostic tool, check data list.

CAUTION

To prevent damage to diagnostic tool, always turn the igni-
tion switch to the "LOCK" (OFF) position before connect-
ing or disconnecting diagnostic tool.
(1) Connect diagnostic tool to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check the following items in the data list. Refer to Data List 

Reference Table 

P.13A-637

.

a. Item 5: Engine Coolant Temperature Sensor.
b. Item 6: Intake Air Temperature Sensor.

c. Item AD: Right Bank Heated Oxygen Sensor (rear).

d. Item AC: Right Bank Heated Oxygen Sensor (front).
e. Item AF: Left Bank Heated Oxygen Sensor (rear).

f. Item AE: Left Bank Heated Oxygen Sensor (front). 

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Are they operating properly?

YES : Go to Step 4.
NO :  Repair or replace it. Then confirm that the malfunction 

symptom is eliminated.

STEP 4. Using diagnostic tool, check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items of the data list. Refer to Data List 

Reference Table 

P.13A-637

.

a. Item AC: Right Bank Heated Oxygen Sensor (front).
b. Item AE: Left Bank Heated Oxygen Sensor (front).

• Voltage should fluctuate between 0 − 0.4 volt and 0.6 − 

1.0 volt while idling after the engine has been warmed.

(3) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Are they operating properly?

YES : Replace the heated oxygen sensor (front). Then 

confirm that the malfunction symptom is eliminated. If 
not resolved, go to step 6.

NO :  Go to Step 5.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-602

STEP 5. Check the fuel pressure.
Refer to On-vehicle Service 

− Fuel Pressure Test 

P.13A-661

.

Q: Is the fuel pressure normal?

YES : Go to Step 6.
NO :  Repair or replace it. Then confirm that the malfunction 

symptom is eliminated.

STEP 6. Check the following items.
(1) Check the following items, and repair or replace the 

defective items.

a. Check the injectors for fuel leakage.
b. Check the ignition coil and spark plugs.

c. Check compression pressure.

d. Check the positive crank case ventilation system.
e. Check the evaporative emission system.

(2) Then check the malfunction symptom.

Q: Is the malfunction symptom eliminated?

YES : The check is completed.
NO :  Replace the catalytic converter. Then confirm that the 

malfunction symptom is eliminated. 

INSPECTION PROCEDURE 23: Purge Flow Test of the Evaporative Emission Canister Failure.

.

COMMENT

• The test fails when the purge line or purge port is 

clogged or if the evaporative emission purge 
solenoid fails.

.

TROUBLESHOOTING HINTS (The most 
likely causes for this case:)

• Malfunction of the evaporative emission purge 

solenoid.

• Evaporative emission canister is clogged.

• Refer to component locations GROUP-

70

• Refer to configuration diagrams GROUP-

80

• Refer to circuit diagrams GROUP-

90

• Purge line or purge port is clogged.

DIAGNOSIS

Required Special Tools:

• Diagnostic tool(MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991910: Main Harness A

MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS

MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>

13A-603

STEP 1. Using diagnostic tool, read the diagnostic trouble 
code (DTC).

CAUTION

To prevent damage to diagnostic tool, always turn the igni-
tion switch to the "LOCK" (OFF) position before connect-
ing or disconnecting diagnostic tool.
(1) Connect diagnostic tool to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the DTC set?

YES : Refer to Diagnostic Trouble Code Chart 

P.13A-17

.

NO :  Refer to GROUP 17, Emission Control System 

− 

Purge Control System Check (Purge Flow Check) 

P.17-82

.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827