Mitsubishi Montero (2002-2004). Manual — part 749

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SYMPTOM PROCEDURES

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STEP 5. Engine stall reproduction test.
Q: Is it easy to reproduce the engine stall?

YES : Go to Step 6.
NO : Check if the following signals change suddenly by

wiggling the circuit harness and connectors.

a. Crankshaft position sensor signal.
b. Volume airflow sensor signal.

c. Injector drive signal.

d. Primary and secondary ignition signal.
e. Fuel pump drive signal.

f. PCM power supply voltage.

Repair or replace. Then confirm that the malfunction

symptom is eliminated.

STEP 6. Using scan tool MB991502, check data list.

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 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 GROUP

13A, Data List Reference Table

P.13Ab-29

.

a. Item 13: Intake Air Temperature Sensor.
b. Item 25: Barometric Pressure Sensor.

c. Item 21: Engine Coolant Temperature Sensor.

d. Item 69: Right Bank Heated Oxygen Sensor (rear).
e. Item 39: Right Bank Heated Oxygen Sensor (front).

f. Item 59: Left Bank Heated Oxygen Sensor (rear).

g. Item 11: Left Bank Heated Oxygen Sensor (front).
h. Item 27: Power Steering Pressure Switch.

i. Item 28: A/C Switch.
j. Item 68: EGR valve (stepper motor).

k. Item 79: Throttle position sensor (main).

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

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

symptom is eliminated.

ACX01539

16-PIN

MB991502

AC

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SYMPTOM PROCEDURES

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STEP 7. Using scan tool MB991502, check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items of the data list. Refer to GROUP

13A, Data List Reference Table

P.13Ab-29

.

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

• Fluctuates between 0 − 0.4 volts 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: Is the sensor operating properly?

YES : Go to Step 9.
NO : Go to Step 8.

STEP 8. Check the fuel pressure.
Refer to GROUP 13A, On-vehicle Service

− Fuel Pressure Test

P.13Aa-13

.

Q: Is the fuel pressure normal?

YES : Check the following items, and repair or replace the

defective items.

a. Vacuum leak.

• Broken intake manifold gasket.

• Broken air intake hose.

• Broken vacuum hose.

• Positive crankcase ventilation valve does

not operate.

b. Injector clogged.

Then confirm that the malfunction symptom is

eliminated.

NO : Repair or replace. Then confirm that the malfunction

symptom is eliminated.

STEP 9. Check the ignition timing.
Refer to GROUP 11A, On-vehicle Service

− Ignition Timing

Check

P.11A-6

.

Q: Is the ignition timing normal?

YES : Check the following items, and repair or replace the

defective items.

a. Check the ignition coil, spark plugs, spark plug

cables.

b. Check if the injectors are clogged.

c. Check compression pressure.

d. Check if the foreign materials (water,

kerosene, etc.) got into fuel.

e. Check the EGR valve.

Then confirm that the malfunction symptom is

eliminated.

NO : Check that the crankshaft position sensor and timing

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

ACX01539

16-PIN

MB991502

AC

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SYMPTOM PROCEDURES

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INSPECTION PROCEDURE 13: The Engine Stalls when Accelerating (Pass Out).

.

COMMENT

• In case such as the above, the cause is probably

misfiring due to a weak spark, or an inappropriate
air/fuel mixture when the accelerator pedal

.

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

• Vacuum leak.

• Malfunction of the ignition system.

• Malfunction of emission control system.

DIAGNOSIS

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, read the diagnostic
trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 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 DTC set?

YES : Refer to GROUP 13A, Diagnostic Trouble Code Chart

P.13Ab-22

.

NO : Go to Step 2.

STEP 2. Using scan tool MB991502, check actuator test.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the actuator test. Refer to

GROUP 13A, Actuator Test Reference Table

P.13Ab-42

.

a. Item 08: Evaporative Emission Purge Solenoid.

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

YES : Check the following items, and repair or replace the

defective items.

a. Check the ignition coil, spark plugs, spark plug

cables.

b. Check for vacuum leaks.

• Broken intake manifold gasket.

• Broken or disconnected vacuum hose.

• Improper operation of the PCV valve.

• Broken air intake hose.

c. Check the EGR valve.

Then confirm that the malfunction symptom is

eliminated.

NO : Repair or replace. Then confirm that the malfunction

symptom is eliminated.

ACX01539

16-PIN

MB991502

AC

ACX01539

16-PIN

MB991502

AC

TSB Revision

SYMPTOM PROCEDURES

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INSPECTION PROCEDURE 14: The engine stalls when decelerating.

.

COMMENT

• The intake air volume may be insufficient due to a

defective the electronic control throttle valve sys-
tem.

.

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

• Malfunction of the electronic control throttle valve

system.

DIAGNOSIS

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

STEP 1. Check if the battery terminal is disconnected.
Q: Has the battery terminal been disconnected lately?

YES : Start the engine and let it run at idle for approximate

10 minutes after engine warm up. Then if a
malfunction occurs, go to step 2.

NO : Go to Step 2.

STEP 2. Using scan tool MB991502, read the diagnostic
trouble code (DTC).

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 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 DTC set?

YES : Refer to GROUP 13A, Diagnostic Trouble Code Chart

P.13Ab-22

.

NO : Go to Step 3.

STEP 3. Using scan tool MB991502, check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the data list. Refer to GROUP

13A, Data List Reference Table

P.13Ab-29

.

a. Item 79: Throttle Position Sensor (main).
b. Item 14: Throttle Position Sensor (sub).

c. Item 78: Accelerator Pedal Position Sensor (main).

d. Item 77: Accelerator Pedal Position Sensor (sub).

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

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

symptom is eliminated.

ACX01539

16-PIN

MB991502

AC

ACX01539

16-PIN

MB991502

AC