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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