Mitsubishi Space Star. Manual — part 71
MPI –
Troubleshooting
13B-71
CHECK AT THE ENGINE-ECU TERMINALS
TERMINAL VOLTAGE CHECK CHART
The following items have been added. The ignition timing adjustment terminal (terminal No. 52) has been
discontinued.
Terminal No.
Check item
Check condition
Normal condition
10
Ignition coil – No. 1,
No. 4 (Ignition power
transistor)
Engine r/min: 3,000 r/min
0.3 – 3.0 V
23
Ignition coil – No. 2,
No. 3 (Ignition power
transistor)
Engine r/min: 3,000 r/min
0.3 – 3.0 V
58
Engine ignition signal
Engine r/min: 3,000 r/min
0.3 – 3.0 V
88
Camshaft position
sensor
Engine: Cranking
0.4 – 3.0 V
sensor
Engine: Idling
0.5 – 2.0 V
CHECK CHART FOR RESISTANCE AND CONTINUITY BETWEEN TERMINALS
Terminal No.
Check item
Normal condition (check condition)
54 – 12
Oxygen sensor heater (rear)
4.5 – 8.0
Ω
(at 20
C)
60 – 12
Oxygen sensor heater (front)
11 – 18
Ω
(at 20
C)
MPI –
Troubleshooting
13B-72
INSPECTION PROCEDURE USING AN
ANALYZER
CAMSHAFT POSITION SENSOR AND CRANK ANGLE
SENSOR
Measurement Method
1.
Disconnect the camshaft position sensor connector and
connect the special tool (test harness: MB991709) in
between. (All terminals should be connected.)
2.
Connect the analyzer special patterns pickup to camshaft
position sensor terminal 2.
3.
Disconnect the crank angle sensor connector and connect
the special tool (test harness: MD998478) in between.
4.
Connect the analyzer special patterns pickup to crank
angle sensor terminal 2.
Alternate Method (Test harness not available)
1.
Connect the analyzer special patterns pickup to
engine-ECU terminal 88. (When checking the camshaft
position sensor signal wave pattern.)
2.
Connect the analyzer special patterns pickup to
engine-ECU terminal 89. (When checking the crank angle
sensor signal wave pattern.)
Standard Wave Pattern
Observation conditions
Function
Special patterns
Pattern height
Low
Pattern selector
Display
Engine r/min
Idle speed
Crank angle
sensor connector
Camshaft position sen-
sor connector
Analyzer
Special patterns
pick-up
MPI –
Troubleshooting
13B-73
Standard wave pattern
Crank angle
sensor output
wave pattern
(V)
75
BTDC
2 engine revolutions
(1 camshaft revolution)
5
BTDC
The time (cycle time) T is
reduced when the engine
speed increases
0
Camshaft posi-
tion sensor out-
put wave pat-
tern
TDC: Top dead centre
130
°
50
°
No. 1
TDC
No. 3 TDC
No. 4
TDC
No. 2
TDC
Time
0
145
°
35
°
Wave Pattern Observation Points
Check that cycle time T becomes shorter when the engine speed increases.
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 disk
Wave pattern characteristics
Wave pattern is displaced to the left or right.
MPI –
Troubleshooting
13B-74
IDLE SPEED CONTROL (ISC) SERVO (STEPPER
MOTOR)
Measurement Method
1.
Disconnect the ISC servo connector, and connect the
special tool (test harness: MB991709) in between. (All
terminals should be connected.)
2.
Connect the analyzer special patterns pickup to the ISC
servo-side connector terminal 1, terminal 3, terminal 4
and terminal 6 respectively.
Alternate Method (Test harness not available)
1.
Connect the analyzer special patterns pickup to
engine-ECU terminal 4, connection terminal 5, connection
terminal 17, and connection terminal 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 OFF to ON (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
The wave pattern
appears for an
instant, but soon
disappears.
Point B
Coil reverse
electromotive force
(Approx. 3
×
10 V)
Point A
Induced electro-
motive force from
the motor turning
(V)
30
20
10
ISC
servo
control
signal
pat-
tern
Time
Special patterns pickup
Analyzer
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