Mitsubishi Lancer Evolution 7. Manual — part 205
MPI -
Troubleshooting
13A-119
D
Example 2
Cause of problem
Loose timing belt
Abnormality in sensor disk
Wave pattern characteristics
Wave pattern is displaced to the left or right.
INJECTOR
Measurement Method
1. Disconnect the injector connector, and then connect the
special tool (test harness: MB991348) in between.
(All terminals should be connected.)
2. Connect the analyzer special patterns pickup to terminal
No. 2 of the injector connector.
Alternate Method (Test harness not available)
1. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 1. (When checking the No. 1
cylinder.)
2. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 14. (When checking the No.
2 cylinder.)
3. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 2. (When checking the No. 3
cylinder.)
4. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 15. (When checking the No.
4 cylinder.)
Standard Wave Pattern
Observation conditions
Function
Special patterns
Pattern height
Variable
Variable knob
Adjust while viewing the wave pattern
Pattern selector
Display
Engine r/min
Idle speed
Special
patterns
pickup
Analyzer
MPI -
Troubleshooting
13A-120
Standard wave pattern
(V)
Point A
Point B
Solenoid back electromotive force
(Approx. 7×10 V)
Injector drive time
Power voltage
Drive signal: ON
Drive signal: OFF
Time
50
0
Wave Pattern Observation Points
Point A: Height of solenoid back electromotive force
Contrast with standard wave pattern
Probable cause
Solenoid coil back electromotive force is low or doesn’t
appear at all.
Short in the injector solenoid
Point B: Injector drive time
D
The injector drive time will be synchronized with the MUT-II
tester display.
D
When the engine is suddenly raced, the drive time will
be greatly extended at first, but the drive time will soon
match the engine speed.
When idling
When racing
---
- -
MPI -
Troubleshooting
13A-121
IDLE SPEED CONTROL SERVO (STEPPER MOTOR)
Measurement Method
1. Disconnect the idle speed control servo connector, and
connect the special tool (test harness: MB991709) in
between.
2. Connect the analyzer special patterns pickup to the idle
speed control servo-side connector terminal No. 1,
terminal No. 3, terminal No. 4 and terminal No. 6
respectively.
Alternate Method (Test harness not available)
1. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 4, connection terminal No. 5,
connection terminal No. 17, and connection terminal No.
18 respectively.
Standard Wave Pattern
Observation conditions
Function
Special patterns
Pattern height
High
Pattern selector
Display
Engine condition
When the engine coolant temperature is 20_C or below, turn the ignition switch from “LOCK”
(OFF) position to “ON” position (without starting the engine).
While the engine is idling, turn the A/C switch to ON.
Immediately after starting the warm engine
Standard wave pattern
Stepper
motor
control
signal
wave
pattern
(V)
30
20
10
The wave pattern
appears for an
instant, but soon
disappears.
Point B
Coil reverseelectromotive
force (Approx. 3 × 10 V)
Point A
Induced electromotive force
from the motor turning
Time
Special
patterns
pickup
Analyzer
MPI -
Troubleshooting
13A-122
Wave Pattern Observation Points
Check that the standard wave pattern appears when the stepper motor is operating.
Point A: Presence or absence of induced electromotive force from the motor turning. (Refer to the abnormal
wave pattern.)
Contrast with standard wave pattern
Probable cause
Induced electromotive force does not appear or is extremely small.
Motor is malfunctioning
Point B: Height of coil reverse electromotive force
Contrast with standard wave pattern
Probable cause
Coil reverse electromotive force does not appear or is extremely small.
Short in the coil
Examples of Abnormal Wave Pattern
D
Example 1
Cause of problem
Motor is malfunctioning. (Motor is not operating.)
Wave pattern characteristics
Induced electromotive force from the motor turning does
not appear.
D
Example 2
Cause of problem
Open circuit in the line between the stepper motor and
the engine-ECU.
Wave pattern characteristics
Current is not supplied to the motor coil on the open
circuit side. (Voltage does not drop to 0 V.)
Furthermore, the induced electromotive force waveform
at the normal side is slightly different from the normal
waveform.
Open
circuit
side
Normal
side
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