Mitsubishi Montero (2004+). Manual - part 372

 

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Mitsubishi Montero (2004+). Manual - part 372

 

 

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-975

INSPECTION PROCEDURE USING AN 
OSCILLOSCOPE

M1131154500640

VOLUME AIRFLOW SENSOR

Required Special Tool:

• MB991709: Test Harness

.

Measurement Method
1. Disconnect the volume airflow sensor connector, and 

connect the test harness special tool (MB991709) in 
between. (All terminals should be connected.)

2. Connect the oscilloscope probe to volume airflow sensor 

connector terminal No. 3.

.

Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminal No. 63.
Standard Wave Pattern

Observation condition

Function

Special pattern

Pattern height

Low

Pattern selector

Display

Engine r/min

Idle speed

Observation condition

Rev engine, observe T1 and T2 remain equal.

AK102975AC

1 2 3 4 5 6 7

VOLUME AIRFLOW 
SENSOR CONNECTOR

OSCILLOSCOPE

MB991709

AKX01595

THE TIME (CYCLE TIME) T IS REDUCED WHEN THE
AMOUNT OF INTAKE AIR INCREASES.

TIMES T

1

 AND T

2

 ARE EQUAL

T

T

1

T

2

10

0

(V)

TIME

AB

Standard wave pattern

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-976

Wave Pattern Observation Points

1. Check that cycle time T becomes shorter and the frequency 

increases when the engine speed is 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

• Damaged rectifier or vortex generation column.

Wave pattern characteristics

• Unstable wave pattern with non-uniform frequency. An 

ignition leak will distort the wave pattern temporarily, 
even if the volume airflow sensor is normal.

AKX01596

10

0

(V)

T

TIME

AB

Standard wave pattern

AKX01597

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-977

CAMSHAFT POSITION SENSOR AND 
CRANKSHAFT POSITION SENSOR

Required Special Tools:

• MB991658: Test Harness

• MD998478: Test Harness

.

Measurement Method
1. Disconnect the camshaft position sensor intermediate 

connector, and connect the test harness special tool 
(MB991658) in between. (All terminals should be 
connected.)

2. Connect the oscilloscope probe to camshaft position sensor 

intermediate connector terminal No. 2.

3. Disconnect the crankshaft position sensor connector, and 

connect the test harness special tool (MD998478) in 
between.

4. Connect the oscilloscope probe to crankshaft position 

sensor connector terminal No. 2 (black clip of special tool).

.

Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminal No. 71. 

(Check the camshaft position sensor signal wave pattern.)

2. Connect the oscilloscope probe to PCM terminal No. 70. 

(Check the crankshaft position sensor signal wave pattern.)

Standard Wave Pattern

Observation condition

Function

Special pattern

Pattern height

Low

Pattern selector

Display

Engine r/min

Idle speed

AK102978AC

CAMSHAFT POSITION 
SENSOR INTERMEDIATE
CONNECTOR

MB991658

OSCILLOSCOPE

3

2

1

AK102979AB

MD998478

1 2

3

CRANKSHAFT POSITION
SENSOR CONNECTOR

OSCILLOSCOPE

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-978

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

 

 

 

 

 

 

 

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