Mitsubishi Eclipse / Eclipse Spyder (2000-2002). Service and repair manual — part 336
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L ENGINE>
13B-543
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 ECM <M/T> or PCM <A/T>.
•
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 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) <3.0L ENGINE>
13B-544
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 ignition coil connector
terminal 3.
Alternate method (Test harness not available)
1. Connect the oscilloscope probe to ECM <M/T> or PCM <A/
T> terminal 11.
Standard Wave Pattern
Wave Pattern Observation Points
Point: Condition of wave pattern build-up section and maximum
voltage (Refer to abnormal wave pattern examples 1 and 2.
Observation conditions
Function
Special pattern
Pattern height
Low
Pattern selector
Display
Engine r/min
Approximately 1,200 r/min
AK000067
1 2 3 4 5 6 7
OSCILLOSCOPE
DISTRIBUTOR
CONNECTOR
OSCILLO
SCOPE
PLOBE
AB
AK000069
CRANKSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN
(REFERENCE)
IGNITION POWER
TRANSISTOR
CONTROL SIGNAL
WAVE PATTERN
POINT:
WAVE BUILD-UP
SECTION
Standard wave pattern
θ
θ
: SPARK ADVANCE ANGLE
ON
DWELL SECTION
TIME
OFF
T
T : CRANKSHAFT ANGLE (120˚)
COMPRESSION
TOP DEAD CENTER
0
2
4
6
0
2
4
6
(V)
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L ENGINE>
13B-545
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
SPECIAL TOOLS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L ENGINE>
13B-546
SPECIA L TO O LS
M1131000600063
TOOL
TOOL NUMBER AND
NAME
SUPERSESSION
APPLICATION
MB991502
Scan tool <MUT-II>
MB991496-OD
•
Reading diagnostic
trouble code
•
MFI system inspection
•
Measurement of fuel
pressure
MB991348
Test harness set
MB991348-01
•
Adjustment of throttle
position sensor
•
Inspection using an
oscilloscope
MB991709
Test harness set
MB991709-01
•
Inspection using an
oscilloscope
•
Inspection of idle air
control motor
MB991658
Test harness set
Tool not available
Inspection of heated
oxygen sensor
MD998464
Test harness (4 pin,
square)
MD998464-01
•
Inspection of heated
oxygen sensor
•
Inspection using an
oscilloscope
MB991316
Test harness (4 pin,
square)
Tool not available
•
Inspection of heated
oxygen sensor
MD998478
Test harness (3 pin,
triangle)
MD998478-01
Inspection using an
oscilloscope
B991502
MB991348
MB991658
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