Mitsubishi Montero (2002-2004). Manual - part 574

 

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Mitsubishi Montero (2002-2004). Manual - part 574

 

 

INSPECTION PROCEDURE USING AN OSCILLOSCOPE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

13Ab-53

Wave Pattern Observation Points

1. Check that cycle time T becomes shorter when the engine 

speed increased.

.

Examples of Abnormal Wave Patterns
Example 1
Cause of problem

• Sensor interface malfunction.

Wave pattern characteristics

• Rectangular wave pattern is output even when the 

engine is not started.

Example 2
Cause of problem

• Loose timing belt.

• Abnormality in sensor disc.

Wave pattern characteristics

• Wave pattern is displaced to the left or right.

AKX01600

2 ENGINE REVOLUTIONS (1 CAMSHAFT REVOLUTION)

75

BTDC

5

BTDC

T

CYCLE TIME CHANGES
WITH ENGINE SPEED
CHANGES

CRANKSHAFT

POSITION

SENSOR OUTPUT

WAVE PATTERN

CAMSHAFT

POSITION

SENSOR OUTPUT

WAVE PATTERN

TDC: TOP DEAD CENTER

NO.1 TDC

NO.2 TDC

NO.3 TDC

NO.4 TDC

NO.5 TDC

NO.6 TDC

TIME

Standard wave pattern

AB

AKX01597

AKX01602

INSPECTION PROCEDURE USING AN OSCILLOSCOPE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

13Ab-54

INJECTOR

Required Special Tools:

• MD998474: Test Harness

.

Measurement Method
1. Disconnect the injector intermediate connector, and connect 

the test harness special tool (MD998474) in between.

2. Connect the oscilloscope probe to each injector 

intermediate connector terminal to analyze each cylinder:

• Terminal No. 3 (green clip of special tool) for the number 1 

cylinder

• Terminal No. 2 (white clip) for the number 2 cylinder 

• Terminal No. 1 (blue clip) for the number 3 cylinder

• Terminal No. 7 (yellow clip) for the number 4 cylinder

• Terminal No. 6 (red clip) for the number 5 cylinder

• Terminal No. 5 (black clip) for the number 6 cylinder

.

Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminal No. 1. 

(When checking the number 1 cylinder.)

2. Connect the oscilloscope probe to PCM terminalNo.  5. 

(When checking the number 2 cylinder.)

3. Connect the oscilloscope probe to PCM terminal No. 14. 

(When checking the number 3 cylinder.)

4. Connect the oscilloscope probe to PCM terminal No. 21. 

(When checking the number 4 cylinder.)

5. Connect the oscilloscope probe to PCM terminal No. 2. 

(When checking the number 5 cylinder.)

6. Connect the oscilloscope probe to PCM terminal No. 6. 

(When checking the number 6 cylinder.)

Standard Wave Pattern

Observation conditions

Function

Special pattern

Pattern height

Variable

Variable knob

Adjust while viewing the 
wave pattern

Pattern selector

Display

Engine r/min

Idle speed

AK102982 AB

OSCILLOSCOPE

INJECTOR
INTERMEDIATE
CONNECTOR

MD998474

1 2 3 4

5 6 7 8

INSPECTION PROCEDURE USING AN OSCILLOSCOPE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

13Ab-55

Wave Pattern Observation Points
Point A: Height of injector coil induced voltage.

Point B: Injector drive time

1. The injector drive time should be synchronized with the 

scan tool tester display.

2. When the engine is suddenly revved, the drive time will 

be greatly extended at first, but the drive time will soon 
return to original length.

CONTRAST WITH 
STANDARD WAVE 
PATTERN

PROBABLE CAUSE

Injector coil induced voltage is 
low or doesn't appear at all

Short in the injector solenoid

AKX01604

(V)

50

0

DRIVE SIGNAL:"ON"

POINT B:
INJECTOR DRIVE 
TIME

POINT A

DRIVE SIGNAL:"OFF"

POWER VOLTAGE

INJECTION COIL INDUCED
VOLTAGE (APPROXIMATELY 50-60 V)

AB

Standard wave pattern

AKX01605

WHEN IDLING

WHEN RACING

AB

INSPECTION PROCEDURE USING AN OSCILLOSCOPE

TSB Revision

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

13Ab-56

EGR VALVE (STEPPER MOTOR)

Required Special Tool:

• MB991658: Test Harness

.

Measurement Method
1. Disconnect the EGR valve connector, and connect the test 

harness special tool (MB991658) in between. (All terminals 
should be connected.) 

2. Connect the oscilloscope probe to the EGR valve connector 

terminal No. 1, terminal No. 3, terminal No.  4, No. terminal 6 
respectively.

.

Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminals No. 3, No. 

12, No. 19 and No. 26.

Standard Wave Pattern

Wave Pattern Observation Points

1. Check that the standard wave pattern appears when the 

EGR valve is operating.

Point A: Presence or absence of induced electromotive force 

from the motor turning. (Refer to abnormal wave pattern.)

Observation condition

Function

Special pattern

Pattern height

High

Pattern selector

Display

Engine condition

Racing

CONTRAST WITH 
STANDARD WAVE 
PATTERN

PROBABLE CAUSE

Induced electromotive force 
does not appear or is 
extremely small

Malfunction of motor

AK201315

1 2 3
4 5 6

EGR VALVE
CONNECTOR

OSCILLOSCOPE

MB991658

AB

AKX01607 AB

(V)

30

20

10

0

IAC
MOTOR
CONTROL
SIGNAL
WAVE
PATTERN

THE WAVE PATTERN
APPEARS FOR AN
INSTANT, BUT SOON
DISAPPEARS.

POINT B COIL RE-
VERSE ELECTRO-
MOTIVE FORCE
(APPROXIMATELY
3 x10 V)

POINT AN INDUCED
ELECTROMOTIVE
FORCE FROM THE
MOTOR TURNING

TIME

Standard wave pattern

 

 

 

 

 

 

 

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