Mitsubishi Montero (2004+). Manual - part 352

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-895

STEP 4. Using scan tool MB991958, 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-950

a. Item 39: Right Bank Heated Oxygen Sensor (front).
b. Item 11: Left Bank Heated Oxygen Sensor (front).

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

1.0 volts while idling after the engine has been warmed.

(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor 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.

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

− Fuel Pressure Test

P.13A-995

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, spark plugs, spark plug cables.

c. Check compression pressure.

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

f. Check the EGR 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.

AK302970

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-896

INSPECTION PROCEDURE 23: Transient, Mass Emission Tailpipe Test Failure.

COMMENT

• The test is failed when the air/fuel ratio is not con-

trolled to the ideal air/fuel ratio. This occurs due
to the feedback control by heated oxygen sensor
signals, insufficient EGR flow rate, or deteriorated
catalyst.

NOTE: If the three-way catalyst temperature is low
when checking the exhaust gas, the three-way cata-
lyst cannot sufficiently clean the emissions. Warm up
the engine sufficiently before checking the exhaust,
and check immediately.

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

• Malfunction of air/fuel ratio control system.

• Malfunction of the EGR system.

• Deteriorated catalyst.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: USB Cable

• MB991911: Main Harness B

STEP 1. Check the exhaust gas with the engine at normal
operating temperature.
Q: After enough warm up, was the exhaust gas checked

enough?
YES : Go to Step 2.
NO : Check it again after enough warm up.

STEP 2. Check the following items.
(1) Check the following items.

a. Check all vacuum hoses and connectors.
b. Check electrical wires and connectors for obvious prob-

lems.

c. Check the exhaust system for missing or damaged

parts.

Q: Are they normal?

YES : Go to Step 3.
NO : Repair or replace it. Then confirm that the malfunction

symptom is eliminated.

STEP 3. Check the driveability.
(1) Check if the malfunction symptom described on the

symptom chart is occurring.

Q: Is the drivability normal?

YES : Go to Step 4.
NO : Refer to Trouble Symptom Chart

P.13A-30

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-897

STEP 4. Using scan tool MB991958, read the diagnostic
trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 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-26

NO : Go to Step 5.

STEP 5. Check the ignition timing.
Refer to GROUP 11A, On-vehicle Service

− Ignition Timing

Check

P.11A-7

Q: Is the ignition timing normal?

YES : Go to Step 6.
NO : Check that the crankshaft position sensor and timing

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

STEP 6. Using scan tool MB991958, check data list.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 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-950

a. Item 21: Engine Coolant Temperature Sensor.
b. Item 13: Intake Air Temperature Sensor.

c. Item 25: Barometric pressure Sensor.

d. Item 69: Right Bank Heated Oxygen Sensor (rear).
e. Item 59: Left Bank Heated Oxygen Sensor (rear).

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : Go to Step 7.
NO : Repair or replace it. Then confirm that the malfunction

symptom is eliminated.

AK302970

MB991911

MB991824

MB991827

AK302970

MB991911

MB991824

MB991827

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-898

STEP 7. Using scan tool MB991958, check data list item 39:
Heated oxygen sensor bank 1, sensor 1 (right front).
(1) Start the engine and run at idle.
(2) Set scan tool MB991958 to the data reading mode for item

39, Heated Oxygen Sensor bank 1, sensor 1 (right front).

• Warm up the engine. When the engine is decelerated

suddenly from 4,000 r/min, the output voltage should
increase from 200 millivolts or less to 600

− 1,000 milli-

volts in a few seconds.

(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : Go to Step 8.
NO : Refer to DTC P0130 - Heated Oxygen Sensor Circuit

(bank 1, sensor 1)

P.13A-167

, DTC P0131 - Heated

Oxygen Sensor Low Voltage (bank 1, sensor 1)

P.13A-184

, DTC P0132 - Heated Oxygen Sensor

Circuit High Voltage (bank 1, sensor 1)

P.13A-191

DTC P0133 - Heated Oxygen Sensor Circuit Slow
Response (bank 1, sensor 1)

P.13A-196

, DTC P0134

- Heated Oxygen Sensor Circuit No Activity Detected
(bank 1, sensor 1)

P.13A-202

STEP 8. Using scan tool MB991958, check data list item 11:
Heated oxygen sensor bank 2, sensor 1 (left front).
(1) Start the engine and run at idle.
(2) Set scan tool MB991958 to the data reading mode for item

11, Heated Oxygen Sensor bank 2, sensor 1 (left front).

• Output voltage should be 0.6 − 1.0 volts at sudden

engine revving.

(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : Go to Step 9.
NO : Refer to DTC P0150 - Heated Oxygen Sensor Circuit

(bank 2, sensor 1)

P.13A-268

, DTC P0151 - Heated

Oxygen Sensor Circuit Low Voltage (bank 2, sensor
1)

P.13A-284

, DTC P0152 - Heated Oxygen Sensor

Circuit High Voltage (bank 2, sensor 1)