Mitsubishi Eclipse. Manual — part 636
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-1087
Standard Wave Pattern
Wave Pattern Observation Points
1. Check that cycle time T becomes shorter and the frequency
increases when the engine speed is increased.
.
Observation conditions
Function
Special pattern
Pattern height
Low
Pattern selector
Display
Engine r/min
Idle speed
Observation conditions
Rev engine, observe T1 and T2 remain equal.
AKX01595
THE TIME (CYCLE TIME) T IS REDUCED WHEN THE
AMOUNT OF INTAKE AIR INCREASES.
TIMES T
1
AND T
2
ARE EQUAL
T
T
1
T
2
10
0
(V)
TIME
AB
Standard wave pattern
AKX01596
10
0
(V)
T
TIME
AB
Standard wave pattern
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-1088
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
Damaged rectifier or vortex generation column.
• Wave pattern characteristics
Unstable wave pattern with non-uniform frequency. An igni-
tion leak will distort the wave pattern temporarily, even if the
volume airflow sensor is normal.
CAMSHAFT POSITION SENSOR AND
CRANKSHAFT POSITION SENSOR
Required Special Tools:
• MB991348: Test Harness
• MD998478: Test Harness
.
Measurement Method
1. Disconnect the camshaft position sensor connector, and
connect the test harness special tool (MB991348) in
between. (All terminals should be connected.)
2. Connect the oscilloscope probe to camshaft position sensor
connector terminal 5.
3. Disconnect the crankshaft position sensor connector, and
connect the test harness special tool (MD998478) in
between.
4. Connect the oscilloscope probe to crankshaft position
sensor connector terminal 2 (black clip of special tool).
.
Alternate method (Test harness not available)
<M/T>
1. Connect the oscilloscope probe to ECM terminal 50. (Check
the camshaft position sensor signal wave pattern.)
2. Connect the oscilloscope probe to ECM terminal 43. (Check
the crankshaft position sensor signal wave pattern.)
<A/T>
1. Connect the oscilloscope probe to PCM terminal 56. (Check
the camshaft position sensor signal wave pattern.)
2. Connect the oscilloscope probe to PCM terminal 45. (Check
the crankshaft position sensor signal wave pattern.)
AKX01597
AK102977AB
1 2 3 4 5 6 7
CAMSHAFT POSITION
SENSOR CONNECTOR
OSCILLOSCOPE
MB991348
AK102979AB
MD998478
1 2
3
CRANKSHAFT POSITION
SENSOR CONNECTOR
OSCILLOSCOPE
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-1089
Standard Wave Pattern
Wave Pattern Observation Points
1. 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.
Observation conditions
Function
Special pattern
Pattern height
Low
Pattern selector
Display
Engine r/min
Idle speed
AKX01600
2 ENGINE REVOLUTIONS (1 CAMSHAFT REVOLUTION)
75
BTDC
5
BTDC
T
CYCLE TIME CHANGES
WITH ENGINE SPEED
CHANGES
CRANKSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN
CAMSHAFT
POSITION
SENSOR OUTPUT
WAVE PATTERN
TDC: TOP DEAD CENTER
NO.1 TDC
NO.2 TDC
NO.3 TDC
NO.4 TDC
NO.5 TDC
NO.6 TDC
TIME
Standard wave pattern
AB
AKX01597
MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-1090
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 cylin-
der
• 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 har-
ness special tool (MB991348) in between. (All terminals
should be connected.)
2. Connect the oscilloscope probe to injector connector termi-
nal 2.
Alternate method (Test harness not available)
1. Connect the oscilloscope probe to ECM <M/T> or PCM
<A/T> terminal 1. (When checking the number 1 cylinder.)
2. Connect the oscilloscope probe to ECM <M/T> or PCM
<A/T> terminal 9. (When checking the number 2 cylinder.)
3. Connect the oscilloscope probe to ECM <M/T> or PCM
<A/T> terminal 24. (When checking the number 3 cylinder.)
4. Connect the oscilloscope probe to ECM <M/T> or PCM
<A/T> terminal 2. (When checking the number 4 cylinder.)
5. Connect the oscilloscope probe to ECM <M/T> or PCM
<A/T> terminal 10. (When checking the number 5 cylinder.)
6. Connect the oscilloscope probe to ECM <M/T> or PCM
<A/T> terminal 25. (When checking the number 6 cylinder.)
AKX01602
AK102981
INJECTOR INTERMEDIATE
CONNECTOR
MD998464
OSCILLOSCOPE
AB
1
3 4
2
AK102980
1 2
INJECTOR
CONNECTOR
MB991348
AB
OSCILLOSCOPE
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