Mitsubishi Montero Sport (2004+). Manual — part 364
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-869
IDLE AIR CONTROL MOTOR (STEPPER MOTOR)
Required Special Tools:
• 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 No. 1, terminal No. 3, terminal No. 4 and
terminal No. 6 respectively.
.
Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminals No. 14,
No. 15, No. 28 and No. 29.
Standard Wave Pattern
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).
AK102983AB
1 2 3
4 5 6
IDLE AIR CONTROL
MOTOR CONNECTOR
OSCILLOSCOPE
MB991709
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)
13A-870
Wave Pattern Observation Points
1. 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.
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 cir-
cuit side. (Voltage does not drop to 0 volt.) Furthermore,
the induced electromotive force wave pattern at the nor-
mal side is slightly different from the normal wave pat-
tern.
CONTRAST WITH
STANDARD WAVE
PATTERN
PROBABLE CAUSE
Induced electromotive force
does not appear or is
extremely small
Malfunction of motor
CONTRAST WITH
STANDARD 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
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-871
IGNITION COIL AND IGNITION POWER
TRANSISTOR
Required Special Tool:
• MB991348: Test Harness Set
.
Measurement Method
1. Disconnect the connector, and connect test harness special
tool (MB991348) in between. (All terminals should be
connected.)
2. Connect the oscilloscope probe to each ignition power
transistor connector terminal to analyze each cylinder:
• Terminal No. 1 for the number 3 and 6 cylinders
• Terminal No. 2 for the number 2 and 5 cylinders
• Terminal No. 3 for the number 1 and 4 cylinders
.
Alternate method (Test harness not available)
1. Connect the oscilloscope probe to PCM terminal No. 11.
(When checking the number 1 and 4 cylinders.)
2. Connect the oscilloscope probe to PCM terminal No. 12.
(When checking the number 3 and 6 cylinders.)
3. Connect the oscilloscope probe to PCM terminal No. 13.
(When checking the number 2 and 5 cylinders.)
Standard Wave Pattern
Observation conditions
Function
Special pattern
Pattern height
Variable
Pattern selector
Display
Engine r/min
Approximately 1,200 r/min
AK102986
1 2 3 4 5 6
OSCILLOSCOPE
IGNITION POWER
TRANSISTOR
MB991348
AB
AK000726
0
2
4
6
0
2
4
6
T
T : CRANKSHAFT ANGLE (120
)
COMPRESSION
TOP DEAD CENTER
POINT : WAVE
BUILD-UP
SECTION
˘
˘
:SPARK
ADVANCE
ANGLE
ON
DWELL SECTION
OFF
TIME
(V)
IGNITION POWER
TRANSISTOR
CONTROL SIGNAL
WAVE PATTERN
CRANKSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN
(REFERENCE)
Standard wave pattern
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI)
13A-872
Wave Pattern Observation Points
Point: Condition of wave pattern build-up section and maximum
voltage (Refer to abnormal wave pattern examples 1 and
2.)
.
Examples of Abnormal Wave Patterns
Example 1 (Wave pattern during engine cranking)
Cause of problem
• Open-circuit in ignition primary circuit
Wave pattern characteristics
• Top-right part of the build-up section cannot be seen,
and voltage value is approximately 2 volts too low.
Example 2 (Wave pattern during engine cranking)
Cause of problem
• Malfunction in ignition power transister
Wave pattern characteristics
• Power voltage results when the ignition power transistor
is ON.
CONDITION OF WAVE
PATTERN BUILD-UP
SECTION AND MAXIMUM
VOLTAGE
PROBABLE CAUSE
Rises from approximate 2
volts to approximate 4.5 volts
at the top-right
Normal
2-volt rectangular wave
Open-circuit in ignition primary
circuit
Rectangular wave at power
voltage
Ignition power transistor
malfunction
AKX01612
NORMAL WAVE
PATTERN
2V
AB
AKX01613
BATTERY
POSITION
VOLTAGE
NORMAL WAVE
PATTERN
AB
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