engine MITSUBISHI LANCER EVOLUTION IV 1998 Repair Manual

MPI – Troubleshooting13-25
6-2 RESISTANCE AND CONTINUITY BETWEEN HARNESS SIDE CONNECTORS AND
TERMINALS
Engine-ECU Harness Side Connector Terminal Arrangement
Terminal No.Inspection itemNormal condition (Check condition)
1 – 12No.1 injector2 – 3 Ω (At 20C)
14 – 12No.2 injector
2 – 12No.3 injector
15 – 12No.4 injector
3 – 12Fuel pressure control valve28 – 36 Ω (At 20C)
4 – 12Stepper motor coil (A1)28 – 33 Ω (At 20C)
17 – 12Stepper motor coil (A2)
5 – 12Stepper motor coil (B1)
18 – 12Stepper motor coil (B2)
6 – 12Secondary air control solenoid valve28 – 36 Ω (At 20C)
11 – 12Wastegate solenoid valve62 – 74 Ω (At 20C)
13 – Body earthEngine-ECU earthContinuity established (0 Ω)
26 – Body earth
60 – 12Oxygen sensor heater (EVOLUTION-V
only)11 – 18 Ω (at 20C)
72 – 92Intake air temperature sensor5.3 – 6.7 kΩ (When intake air temperature is 0C)
2.3 – 3.0 kΩ (When intake air temperature is 20C)
1.0 – 1.5 kΩ (When intake air temperature is 40C)
0.30 – 0.42 kΩ (When intake air temperature is 80C)
74 – 77High temperature sensor3 Ω or less
83 – 92Engine coolant temperature sensor5.1 – 6.5 kΩ (When coolant temperature is 0C)
2.1 – 2.7 kΩ (When coolant temperature is 20C)
0.9 – 1.3 kΩ (When coolant temperature is 40C)
0.26 – 0.36 kΩ (When coolant temperature is 80C)
87 – 92Idle position switchContinuity established (when throttle valve is at idle
position)
No continuity (when throttle valve is slightly open)
91 – Body earth–Continuity established

MPI – Troubleshooting13-26
7. INSPECTION PROCEDURE USING
OSCILLOSCOPE
7-1 AIR FLOW SENSOR (AFS)
Observing waveforms displayed on the oscilloscope allows
you to visually identify possible unusual disturbances in
waveform that could temporarily occur in the air flow sensor
output.

(1) Disconnect the air flow sensor connector and connect
the special tool (Test Harness: MB991709) to it. (Ensure
that all terminals are connected.)
(2) Connect the oscilloscope probe to terminal no. 3 of air
flow sensor connector.
NOTE
If the engine ECU connector is used, connect the
oscilloscope probe to terminal no. 90.
(3) Perform the same steps from here on as with the 4G9
engine.
7-2 CAMSHAFT POSITION SENSOR AND CRANK
ANGLE SENSOR
Perform the same steps as with the conventional 4G9 engine
for the inspection.
7-3 INJECTOR
Observing waveforms displayed on the oscilloscope allows
you to visually check the conditions of injector drive signals
actually output from the engine ECU.
Injector Control Signal (Oscilloscope 1)

(1) Disconnect the injector connector and connect the special
tool (Test Harness: MB991348) to the circuit. (Ensure
that the terminals on both the power supply and engine
ECU sides are connected.)
(2) Connect the oscilloscope probe to terminal no. 2 of injector
connector.
NOTE
If the engine ECU connector is used for the measurement,
take measurements at each of the following terminals.
Connect the oscilloscope probe to terminal no. 1 when
the waveform is observed with no. 1 cylinder, to terminal
no. 14 when the waveform is observed with no. 2 cylinder,
to terminal no. 2 when the waveform is observed with
no. 3 cylinder, and to terminal no. 15 when the waveform
is observed with no. 4 cylinder.
Oscilloscope
Oscilloscope

MPI – Troubleshooting13-27

Observation conditions
Probe selector switch× 10
AC-GND-DCDC
VOLTS/DIV.1 V
TIME/DIV.0.5 ms
Misc.–
Engine speedIdle

The power supply voltage is being normally applied and, when a signal is received from the engine
ECU, the voltage drops to around 0 V for the period of time equivalent to its drive signal.
When the signal from the engine ECU turns OFF, the counter emf of the coil causes a voltage peak
to develop, thus resuming the power supply voltage.
Injector drive time:
The fuel injection time as determined by the engine ECU according to the output values of sensors
including AFS. Injector drive time = effective injection time + invalid injection time (Invalid injection
time: corrects operation time lag caused by a power supply voltage drop)
Solenoid coil counter emf:
When the signal from the engine ECU turns OFF, counter emf occurs in the injector coil (approx.
65 to 75 V).
Power supply voltage:
The power supply voltage is being applied in the absence of a signal from the engine ECU. If this
voltage is low, it extends the invalid injection time and, thus, the drive time.

Point A: Strength of solenoid coil counter emf
Solenoid coil counter emf is low or zero.Injector solenoid shorting
Point B: Injector drive time
When the engine is suddenly raced, the drive time temporarily
extends by a wide margin and soon returns to the normal
drive time corresponding to the engine speed.
Point A
Point B
Injector
drive timeSolenoid counter emf
(approx. 7 × 10 V)
Power supply voltage
At idle
During racing

MPI – Troubleshooting13-28
Injector Power Supply Voltage (Oscilloscope 2)

(1) Disconnect the resistor connector and connect the special
tool (Harness Connector: MD998463) to the circuit.
(2) Connect the oscilloscope probe to resistor connector
terminal (1) (special tool red clip) when the waveform
is observed with no. 1 cylinder, to terminal (4) (black
clip) when the waveform is observed with no. 2 cylinder,
to terminal (5) (green clip) when the waveform is observed
with no. 3 cylinder, and to terminal (6) (yellow clip) when
the waveform is observed with no. 4 cylinder.
(3) For the power supply voltage, observe the waveform of
the injector control signal at the same time. (Refer to
P.13-26 for the injector control signal measurement
procedure.)

Observation conditions
Injector power supply voltage waveformInjector control signal
Probe selector switch× 1× 10
AC-GND-DCACDC
VOLTS/DIV.5 V1 V
TIME/DIV.0.5 ms
Misc.To be timed with injector control signal
Engine speedIdle (850 rpm)
Injector power supply
voltage waveform
(oscilloscope 2)
Injector control signal
waveform
(oscilloscope 1)Plunger in fully
opened position
Point B
Point A
Fuel injection time
Time

MPI – Troubleshooting13-29

The injector power supply voltage waveform shows a voltage drop caused by resistance of the resistor.
As the amount of current increases, voltage gradually decreases and a spike occurs at the plunger fully
opened position due to counter emf.

Point A: Voltage drop during fuel injection time (Refer to abnormal waveform example 1.)
Difference from standard waveformPossible cause
Voltage drop during fuel injection time is small (there
should normally be a voltage drop of about 10 V).Resistance of resistor is too small. Resistance of injector
is too large.
Point B: Spike when plunger is fully open (Refer to abnormal waveform example 2.)
Difference from standard waveformPossible cause
No spike when plunger is fully openPlunger inoperative

Example 1
[Cause of problem]
Resistance of the resistor is too small.
[Waveform characteristics]
Small voltage drop
Example 2
[Cause of problem]
Plunger is inoperative.
[Waveform characteristics]
No spike when plunger is fully open.
7-4 IGNITION COIL
Perform the same steps as with the conventional 4G9 engine
for the inspection.
Abnormal waveform
Normal waveform

MPI – On-vehicle Service13-31
5. MPI SYSTEM COMPONENTS LAYOUT
NameSymbolNameSymbol
A/C switchQExhaust temperature warning lampS
A/C relayHFuel pressure control valveA
Air flow sensor (with a built-in intake air temperaturesensor and barometric pressure sensor)FIgnition coil and power transistor unitLsensor and barometric pressure sensor)InjectorB
Camshaft position sensorMISC servoD
Control relay and fuel pump relayPOxygen sensorK
Coolant temperature sensorEPower steering fluid pressure switchI
Crank angle sensorJSecondary air control solenoid valveN
Detonation sensorCThrottle position sensor (with a built-in idle switch)D
Diagnosis connectorR
Engine ECUOVehicle speed sensorT
Engine warning lampSWastegate solenoid valveG

MPI – On-vehicle Service13-32
6. INTAKE AIR TEMPERATURE SENSOR
CHECK
1. Disconnect the air flow sensor connector.
2. Measure resistance between terminals 5 and 6.
Standard value:
2.3 – 3.0 kΩ (at 20C)
0.30 – 0.42 kΩ (at 80C)
3. Measure resistance while heating the sensor using a hair
drier.
Normal condition:
Temperature (C)Resistance (kΩ)
HigherSmaller
4. If the value deviates from the standard value or the
resistance remains unchanged, replace the air flow sensor
assembly.
7. ENGINE COOLANT TEMPERATURE
SENSOR CHECK
The engine coolant temperature sensor is located as shown
on the left.
Standard value:
2.1 – 2.7 kΩ (at 20C)
0.26 – 0.36 kΩ (at 80C)
8. OXYGEN SENSOR CHECK

The sensor connector is located as shown on the left.

(1) Disconnect the oxygen sensor connector and connect
the special tool (Test Harness: MD998464) to the oxygen
sensor connector.
Equipment sideconnector
Air flow sensor
Intake air temperature sensor
Engine coolant
temperature sensor
Oxygen sensor equipment side connector
Oxygen sensor connector
Oxygen sensor

MPI – On-vehicle Service13-33
(2) Check that there is continuity (11 to 18 Ω at 20C) across
terminal no. 1 (special tool red clip) and terminal no. 3
(special tool blue clip) of the oxygen sensor connector.
(3) If there is no continuity, replace the oxygen sensor.
(4) Run the engine until the engine coolant temperature
exceeds 80C.
(5) Using jumper wires, connect oxygen sensor terminal no.
1 (special tool red clip) and terminal no. 3 (special tool
blue clip) to battery (+) and (–) terminal, respectively.
Caution
Make sure of the correct connections: if a wrong
connection is made, a broken oxygen sensor results.
(6) Connect a digital voltmeter between terminal no. 2 (special
tool black clip) and terminal no. 4 (special tool white clip).
(7) Race the engine repeatedly to measure the oxygen sensor
output voltage.
Standard value:
EngineOxygen sensor
output voltageNOTE
When
engine is
raced0.6 – 1.0 VWhen engine racing is
repeated to enrich air-fuel
ratio, an operational oxygen
sensor should output a volt-
age of 0.6 to 1.0 V.
NOTE
Use the same procedures to remove and install the oxygen
sensor.
Red clip
Blue clip
MD998464
Red clip
Blue clip
MD998464 Black clip
White clip

MPI – On-vehicle Service13-34
9. INJECTOR CHECK
Injection Condition Check
(1) Release the residual pressure from the fuel pipe line to
prevent fuel from flowing out.
(2) Remove the injector.
(3) Set up the special tools (Injector Test Set, Adapter, Fuel
Pressure Regulator, and Clip) as illustrated below.
(4) From here on, use the same procedure as with the
conventional 4G9 engine for the check.
MD998741
MD998706 MB991607Main hose
BatteryInjectorClip: MD998746Return hose
Fuel Pressure Regulator: MD116395
10. RESISTOR CHECK
(1) Disconnect the resistor connector.
(2) Measure resistance across terminals as detailed below.
Standard value
Measurement terminalsResistance (Ω)
1 – 3
4 – 3
5 5 to 6 5 (at 20C)
5 – 3
5.5 to 6.5 (at 20C)
6 – 3
Resistor

MPI – Injector13-36
INJECTOR
REMOVAL AND INSTALLATION
Pre-removal Operation
(1) Fuel Discharge Prevention
(2) Air Hose D Removal
(Refer to GROUP15 – Intercooler.)Post-installation Operation
(1) Air Hose D Installation
(Refer to GROUP15 – Intercooler.)
(2) Fuel Leakage Check
O-ring
9 {0.9}83, 6
11
12
O-ring 10 – 13 {1.0 – 1.3}
Engine oil
1
2 3
4
5
6 78 9
10 11 12
Unit: Nm {kgf
m}
4
Removal steps
1. Injector connector
2. PCV hose connection
A3. High-pressure fuel hose connection
4. Fuel return hose connection
5. Vacuum hose connector
A6. Fuel pressure regulator7. Fuel return pipe
A8. Delivery pipe
9. Insulator
10. Insulator
AA11. Injector
12. Grommet