Mitsubishi 380. Manual — part 640
MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS
MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>
13A-652
INSPECTION PROCEDURE USING AN
OSCILLOSCOPE
M1131154501085
CAMSHAFT POSITION SENSOR AND
CRANKSHAFT POSITION SENSOR
Required Special Tools:
• MB992044: ECU Check Harness
.
Measurement Method
1. Disconnect the all ECU connectors, and connect check
harness special tool (MB992044) between the separated
connectors.
2. Connect the oscilloscope to check harness terminal No. 38.
(Check the camshaft position sensor signal wave pattern.)
3. Connect the oscilloscope to check harness terminal No. 23.
(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
03DB243A
B-20 HARNESS
CONNECTOR
OSCILLOSCOPE
03DB244A
B-20 HARNESS
CONNECTOR
OSCILLOSCOPE
MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS
MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>
13A-653
Wave Pattern Observation Points
1. Check that cycle time 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.
03DB259A
Standard wave pattern
CRANKSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN
CAMSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN
2 ENGINE REVOLUTIONS (1 CAMSHAFT REVOLUTION)
(VOLT)
5
0
5
0
No. 1TDC
No. 3TDC
No. 4TDC
No. 2TDC
(TIME)
AKX01597
AKX01602
MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS
MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>
13A-654
INJECTOR
Required Special Tools:
• MB991658: Test Harness
• MB992044: ECU Check Harness
.
Measurement Method 1
Perform a Power balance Test on all cylinders.
1. Connect MUT III to vehicle and go to Data item list.
2. Scroll to Item No. 72, Absolute load value and lock. Also
lock Item No. 2, Crank angle sensor (engine speed).
3. Go to Actuator test and select Item No. 1, No.1 Injector.
4. Start engine and allow to idle.
5. Perform actuator test on each injecto from 1 to 6 and record
the engine load and speed during each actuator test.
6. Check recorded values for variations between cylinders. If
all injectors are operating correctly there should be minimal
difference between load and engine speed values for all
cylinders.
.
Measurement Method 2
<Measure at the right bank (number 1, 3, 5 cylinders)>
1. Disconnect the intermediate connector B-32, and connect
the test harness special tool (MB991658) between the
separated connector.
2. Connect the oscilloscope probe to each intermediate
connector B-32 terminal to analyze each cylinder:
• Terminal No. 5 for the number 1 cylinder
• Terminal No. 10 for the number 3 cylinder
• Terminal No. 4 for the number 5 cylinder
<Measure at the right bank (number 2, 4, 6 cylinders)>
1. Disconnect the injector connector, and connect the test har-
ness special tool (MB991658) between the separated con-
nector. (All terminals should be connected.)
2. Connect the oscilloscope probe to injector connector termi-
nal No. 2.
Alternate method (Measure at the ECU)
Disconnect the all ECU connectors, and connect check har-
ness special tool (MB992044) between the separated con-
nectors.
00DB076A
MB991910
DATA LINK
CONNECTOR
MB991824
MB991827
AK302166
1 2
INJECTOR
CONNECTOR
MB991658
OSCILLOSCOPE
AB
1 2 3
6 7 8
4 5
9 10
AK203300
OSCILLOSCOPE
MB991658
B-32 INTERMEDIATE
CONNECTOR
AB
MULTIPORT FUEL INJECTION (MPI) DIAGNOSIS
MULTIPORT FUEL INJECTION (MPI) <3.8L ENGINE>
13A-655
3. Connect the oscilloscope probe to each check harness con-
nector terminal to analyze each cylinder:
• Terminal No. 153 for the number 1 cylinder.
• Terminal No. 146 for the number 2 cylinder.
• Terminal No. 140 for the number 3 cylinder.
• Terminal No. 139 for the number 4 cylinder.
• Terminal No. 133 for the number 5 cylinder.
• Terminal No. 127 for the number 6 cylinder.
Standard Wave Pattern
Wave Pattern Observation Points
Point A: Height of injector coil induced voltage.
Observation conditions
Function
Special pattern
Pattern height
Variable
Variable knob
Adjust while viewing the
wave pattern
Pattern selector
Display
Engine r/min
Idle speed
CONTRAST WITH
STANDARD WAVE
PATTERN
PROBABLE CAUSE
Injector coil induced voltage is
low or doesn't appear at all
Short in the injector solenoid
03DB145A
OSCILLOSCOPE
POWER PLANT ECU
CHECK HARNESS
CONNECTOR
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
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