
MPI -Troubleshooting13A-119
DExample 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
FunctionSpecial patterns
Pattern heightVariable
Variable knobAdjust while viewing the wave pattern
Pattern selectorDisplay
Engine r/minIdle speed
Special
patterns
pickupAnalyzer

MPI -Troubleshooting13A-120
Standard wave pattern
(V)
Point A
Point BSolenoid 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 patternProbable cause
Solenoid coil back electromotive force is low or doesn’t
appear at all.Short in the injector solenoid
Point B: Injector drive time
DThe injector drive time will be synchronized with the MUT-II
tester display.
DWhen 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 -Troubleshooting13A-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
FunctionSpecial patterns
Pattern heightHigh
Pattern selectorDisplay
Engine conditionWhen 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
10The wave pattern
appears for an
instant, but soon
disappears.Point B
Coil reverse electromotive
force (Approx. 3×10 V)Point A
Induced electromotive force
from the motor turning
Time
Special
patterns
pickupAnalyzer

MPI -Troubleshooting13A-123
IGNITION COIL AND POWER TRANSISTOR
DIgnition coil primary signal
Refer to GROUP 16 - Ignition system.
DPower transistor control signal
Measurement Method
1. Disconnect the ignition coil connector, and connect the
special tool (test harness: MB991658) in between. (All
terminals should be connected.)
2. Connect the analyzer special patterns pickup to terminal
No. 3 of each ignition coil connector in turn.
Alternate Method (Test harness not available)
1. Connect the analyzer special patterns pickup to
engine-ECU terminal No. 10 (No. 1 - No. 4), terminal
No. 23 (No. 2 - No. 3) respectively.
Standard Wave Pattern
Observation condition
FunctionSpecial patterns
Pattern heightLow
Pattern selectorDisplay
Engine r/minApproximately 1,200 r/min
Standard wave pattern
Crank angle
sensor output
wave pattern
Power transistor
control signal
wave pattern(V)
75_BTDC5_BTDCT: Revolution time corresponding to a crank angle of 180_
Compression top dead center
θ: Spark
advance
angleIgnition period
OFF ON
Dwell section
T1: Time computed by the engine-ECUTime θ T1T
6
4
2
0
4
2
0
Special
patterns
pickupAnalyzer

MPI -On-vehicle Service13A-127
4. If not within the standard value, loosen the throttle position
sensor mounting bolts. Then rotate the sensor body to
adjust.
5. Turn the ignition switch to “LOCK” (OFF) position.
6. Remove the MUT-II. If the MUT-IIis not used, remove
the special tool, and then connect the throttle position
sensor connector.
7. If a diagnosis code is displayed, erase the diagnosis code
by using the MUT-IIor disconnect the negative battery
cable from the battery terminal and then leave it for at
least ten seconds. After that, reconnect the battery cable,
and then let the engine run at idle for approximately 10
minutes.
BASIC IDLE SPEED ADJUSTMENT
NOTE
(1) The basic idling speed has been adjusted by the
speed adjusting screw by the manufacturer, and there
should usually be no need for readjustment.
(2) If the adjustment has been changed by mistake, the
idle speed may become too high or the idle speed
may drop too low when loads from components such
as the A/C are placed on the engine. If this occurs,
adjust by the following procedure.
(3) The adjustment, if made, should be made after first
confirming that the spark plugs, the injectors, the idle
speed control servo, the compression pressure, etc.,
are all normal.
1. Before inspection and adjustment, set the vehicle to the
pre-inspection condition.
2. Connect the MUT-IIto the diagnosis connector (16-pin).
NOTE
When the MUT-IIis connected, the diagnosis control
terminal should be earthed.
3. Start the engine and run at idle.
4. Select the item No. 30 of the MUT-IIActuator test.
NOTE
This holds the idle speed control servo at the basic step
to adjust the basic idle speed.
5. Check the basic idle speed.
Standard value: 850±100 r/min
NOTE
(1) The engine speed may be 20 to 100 r/min lower
than indicated above for a new vehicle [driven
approximately 500 km or less], but no adjustment
is necessary.
(2) If the engine stalls or the engine speed is low even
though the vehicle has been driven approximately
500 km or more, it is probable that deposits are
adhered to the throttle valve, so clean it. (Refer to
P.13A-126.)

MPI -On-vehicle Service13A-135
5. Use the jumper wire to connect terminal No. 1 of the
oxygen sensor connector to the battery (+) terminal and
terminal No. 3 to the battery ( - ) terminal.
Caution
Be very careful when connecting the jumper wire;
incorrect connection can damage the oxygen sensor.
6. Connect a digital voltage meter between terminal No.
2 and terminal No. 4.
7. While repeatedly racing the engine, measure the oxygen
sensor output voltage.
Standard value:
EngineOxygen sensor
output voltageRemarks
When
racing the
engine0.6 - 1.0 VIf you make the air/fuel ratio
rich by racing the engine
repeatedly, a normal oxy-
gen sensor will output a
voltage of 0.6 - 1.0 V.
8. If the sensor is defective, replace the oxygen sensor.
NOTE
For removal and installation of the oxygen sensor, refer
to GROUP 15 - Exhaust Pipe and Main Muffler.
1. Disconnect the oxygen sensor connector and connect
the special tool (test harness set) to the connector on
the oxygen sensor side.
2. Make sure that there is continuity (11 - 18Ωat 20_C)
between terminal No. 3 and terminal No. 4 on the oxygen
sensor connector.
3. If there is no continuity, replace the oxygen sensor.
NOTE
(1) If the MUT-IIdoes not display the standard value
although no abnormality is found by the above
mentioned continuity test and harness check, replace
the oxygen sensor (rear).
(2) For removal and installation of the oxygen sensor,
refer to GROUP 15 - Exhaust Pipe and Main Muffler.
MD998464Blue Black
Red
White Jumper
wire
Oxygen
sensor
(rear)
MB991223
Equipment side connector

ENGINE ELECTRICAL -Charging System16-5
(6) Reconnect the negative battery cable.
(7) Connect a tachometer or the MUT-II.
(Refer to GROUP 11 - On-vehicle Service.)
(8) Leave the hood open.
(9) Start the engine.
(10)With the engine running at 2,500 r/min, turn
the headlamps and other lamps on and off
to adjust the alternator load so that the value
displayed on the ammeter is slightly above 30
A.
Adjust the engine speed by gradually
decreasing it until the value displayed on the
ammeter is 30 A. Take a reading of the value
displayed on the voltmeter at this time.
Limit: max. 0.3 V
NOTE
When the alternator output is high and the value
displayed on the ammeter does not decrease
until 30 A, set the value to 40 A. Read the
value displayed on the voltmeter at this time.
When the value range is 40 A, the limit is max.
0.4 V.(11) If the value displayed on the voltmeter is above
the limit value, there is probably a malfunction
in the alternator output wire, so check the wiring
between the alternator “B” terminal and the
battery (+) terminal (including fusible link).
If a terminal is not sufficiently tight or if the
harness has become discolored due to
overheating, repair and then test again.
(12)After the test, run the engine at idle.
(13)Turn off all lamps and the ignition switch.
(14)Remove the tachometer or the MUT-II.
(15)Disconnect the negative battery cable.
(16)Disconnect the ammeter and voltmeter.
(17)Connect the alternator output wire to the
alternator “B” terminal.
(18)Connect the negative battery cable.
OUTPUT CURRENT TEST
Charging warning lampVoltmeter
Ammeter
Ignition switch
Alternator relayLoad
Battery
Engine-ECUAlternatorFR
L
S
G
+ -+-
B

ENGINE ELECTRICAL -Charging System16-6
This test determines whether the alternator output
current is normal.
(1) Before the test, always be sure to check the
following.
DAlternator installation
DBattery (Refer to GROUP 54 - Battery.)
NOTE
The battery should be slightly discharged.
The load needed by a fully-charged battery
is insufficient for an accurate test.
DAlternator drive belt tension
(Refer to GROUP 11 - On-vehicle Service.)
DFusible link
DAbnormal noise from the alternator while
the engine is running.
(2) Turn the ignition switch to the “LOCK” (OFF)
position.
(3) Disconnect the negative battery cable.
(4) Disconnect the alternator output wire from the
alternator “B” terminal. Connect a DC test
ammeter with a range of 0 - 100 A in series
between the “B” terminal and the disconnected
output wire. (Connect the (+) lead of the
ammeter to the “B” terminal. Connect the ( - )
lead of the ammeter to the disconnected output
wire.)
Caution
Never use clips but tighten bolts and nuts
to connect the line. Otherwise loose
connections (e.g. using clips) will lead to
a serious accident because of high current.
NOTE
An inductive-type ammeter which enables
measurements to be taken without
disconnecting the alternator output wire should
be recommended.
(5) Connect a voltmeter with a range of 0 - 20 V
between the alternator “B” terminal and the
earth. (Connect the (+) lead of the voltmeter
to the “B” terminal, and then connect the ( - )
lead of the voltmeter to the earth.)
(6) Connect the negative battery cable.
(7) Connect a tachometer or the MUT-II.
(Refer to GROUP 11 - On-vehicle Service.)
(8) Leave the hood open.
(9) Check that the reading on the voltmeter is equal
to the battery voltage.
NOTE
If the voltage is 0 V, the cause is probably
an open circuit in the wire or fusible link between
the alternator “B” terminal and the battery (+)
terminal.(10)Turn the light switch on to turn on headlamps
and then start the engine.
(11) Immediately after setting the headlamps to high
beam and turning the heater blower switch to
the high revolution position, increase the engine
speed to 2,500 r/min and read the maximum
current output value displayed on the ammeter.
Limit: 70 % of normal current output
NOTE
DFor the nominal current output, refer to the
Alternator Specifications.
DBecause the current from the battery will
soon drop after the engine is started, the
above step should be carried out as quickly
as possible in order to obtain the maximum
current output value.
DThe current output value will depend on
the electrical load and the temperature of
the alternator body.
DIf the electrical load is small while testing,
the specified level of current may not be
output even though the alternator is normal.
In such cases, increase the electrical load
by leaving the headlamps turned on for
some time to discharge the battery or by
using the lighting system in another vehicle,
and then test again.
DThe specified level of current also may not
be output if the temperature of the alternator
body or the ambient temperature is too
high. In such cases, cool the alternator and
then test again.
(12)The reading on the ammeter should be above
the limit value. If the reading is below the limit
value and the alternator output wire is normal,
remove the alternator from the engine and
check the alternator.
(13)Run the engine at idle after the test.
(14)Turn the ignition switch to the “LOCK” (OFF)
position.
(15)Remove the tachometer or the MUT-II.
(16)Disconnect the negative battery cable.
(17)Disconnect the ammeter and voltmeter.
(18)Connect the alternator output wire to the
alternator “B” terminal.
(19)Connect the negative battery cable.