Mitsubishi Galant. Manual — part 186
MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <2.4L>
13A-425
Wave Pattern Observation Points
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.
AK000062
CYCLE TIME CHANGES
WITH ENGINE SPEED
CHANGES
2 ENGINE REVOLUTIONS (1 CAMSHAFT REVOLUTION)
75˚BTDC
142˚
58˚
63˚ 49˚
5˚BTDC
T
Standard wave pattern
CRANKSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN
CAMSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN
TIME
TDC: TOP DEAD CENTER
NO.1 TDC
NO.2 TDC
NO.3 TDC
NO.4 TDC
0
0
(V)
AB
AKX01597
AKX01602
MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <2.4L>
13A-426
INJECTOR
Required Special Tools:
MD991348: Test Harness Set
Measurement Method
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.)
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
AK000587
OSCILLOSCOPE
OSCILLO
SCOPE
PROBE
1
2
AB
INJECTOR
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
MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <2.4L>
13A-427
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.
IDLE AIR CONTROL MOTOR (STEPPER MOTOR)
Required Special Tool:
MB991709: Test Harness Set
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)
Connect the oscilloscope probe to PCM terminals 14, 15, 28
and 29.
Standard Wave Pattern
CONTRAST WITH
STANDARD WAVE
PATTERN
PROBABLE CAUSE
Injector coil induced voltage is
low or doesn't appear at all
Short in the injector solenoid
AKX01605
WHEN IDLING
WHEN RACING
AC
Observation conditions
Function
Special pattern
Pattern height
High
Pattern selector
Display
Engine condition
Turn the ignition switch from
"LOCK" (OFF) to "ON" posi-
tion (without starting the en-
gine).
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
MULTIPORT FUEL INJECTION(MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <2.4L>
13A-428
Wave Pattern Observation Points
Check that the standard wave pattern appears when the idle air
control motor is operating.
Point A:
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.
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
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
AKX01608 AB
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