Mitsubishi Galant. Manual — part 321
MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-509
Example 2
•
Cause of problem
Loose timing belt.
Abnormality in sensor disc.
•
Wave pattern characteristics
Wave pattern is displaced to the left or right.
INJECTOR
Required Special Tools:
MB991348: Test Harness
MD998464: Test Harness
Measurement Method
<Measure at the right bank (number 1, 3, 5 cylinders)>
1. Disconnect the injector intermediate connector, and connect
the test harness special tool (MD998464) in between.
2. Connect the oscilloscope probe to each injector
intermediate connector terminal to analyze each cylinder:
•
Terminal 2 (black clip of special tool) for the number 1
cylinder
•
Terminal 3 (blue clip) for the number 3 cylinder
•
Terminal 4 (white clip) for the number 5 cylinder
<Measure at the right bank (number 2, 4, 6 cylinders)>
1. Disconnect the injector connector, and connect the test
harness special tool (MB991348) in between. (All terminals
should be connected.)
2. Connect the oscilloscope probe to injector connector
terminal 2.
Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminal 1. (When
checking the number 1 cylinder.)
2. Connect the oscilloscope probe to PCM terminal 9. (When
checking the number 2 cylinder.)
3. Connect the oscilloscope probe to PCM terminal 24. (When
checking the number 3 cylinder.)
4. Connect the oscilloscope probe to PCM terminal 2. (When
checking the number 4 cylinder.)
5. Connect the oscilloscope probe to to PCM terminal 10.
(When checking the number 5 cylinder.)
6. Connect the oscilloscope probe to PCM terminal 25. (When
checking the number 6 cylinder.)
AKX01602
AK000063
1 2
3 4
OSCILLOSCOPE
INJECTOR INTERMEDIATE
CONNECTOR
OSCILLO
SCOPE
PROBE
AB
AK000587
OSCILLOSCOPE
OSCILLO
SCOPE
PROBE
1
2
AB
INJECTOR
CONNECTOR
MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-510
Standard Wave Pattern
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.
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 STAN-
DARD 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
MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-511
IDLE AIR CONTROL MOTOR (STEPPER MOTOR)
Required Special Tool:
MB991709: Test Harness
Measurement Method
1. Disconnect the idle air control motor connector, and connect
the test harness special tool (MB991709) in between. (All
terminals should be connected.)
2. Connect the oscilloscope probe to the idle air control motor
connector terminal 1, terminal 3, terminal 4 and terminal 6,
respectively.
Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminals 14, 15,
28 and 29.
Standard Wave Pattern
Wave Pattern Observation Points
1. Check that the standard wave pattern appears when the
idle air control motor is operating.
Point A:
Observation conditions
Function
Special pattern
Pattern height
High
Pattern selector
Display
Engine condition
Turn the ignition switch from
"OFF" to "ON" (without
starting the engine).
While the engine is idling,
turn the A/C switch to "ON."
Immediately after starting the
warm the engine
(approximately one minute).
AKX01606
6
3
1 2
4 5
OSCILLOSCOPE
OSCILLOSCOPE PLOBE
AKX01606AB
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
MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-512
Presence or absence of induced electromotive force from the
motor turning. (Refer to abnormal wave pattern.)
Point B:
Height of coil back electromotive force
Examples of Abnormal Wave Patterns
Example 1
•
Cause of problem
Malfunction of motor. (Motor is not operating.)
•
Wave pattern characteristics
Induced electromotive force from the motor turning does not
appear.
Example 2
•
Cause of problem
Open circuit in the line between the idle air control motor
and the PCM.
•
Wave pattern characteristics
Current is not supplied to the motor coil on the open circuit
side. (Voltage does not drop to 0 volt.) Furthermore, the
induced electromotive force wave pattern at the normal side
is slightly different from the normal wave pattern.
IGNITION COIL AND IGNITION POWER
TRANSISTOR
Required Special Tool:
MB991348: Test Harness Set
CONTRAST WITH
STANDARD WAVE
PATTERN
PROBABLE CAUSE
Induced electromotive force
does not appear or is
extremely small
Malfunction of motor
CONTRAST WITH STAN-
DARD WAVE PATTERN
PROBABLE CAUSE
Coil reverse electromotive
force does not appear or is
extremely small
Short in the coil
AKX01608 AB
AKX01609
OPEN
CIRCUIT
SIDE
NORMAL
SIDE
AB
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