1998 MITSUBISHI LANCER EVOLUTION IV engine oil

MPI – Troubleshooting13-8
2. INSPECTION CHART FOR DIAGNOSIS CODES
Code No.Diagnosis itemReference page
12Air flow sensor (AFS) system13-8
13Intake air temperature sensor system13-9
14Throttle position sensor (TPS) system13-9
21Engine coolant temperature sensor system13-10
22Crank angle sensor system13-11
23Camshaft position sensor system13-11
24Vehicle speed sensor system13-12
25Barometric pressure sensor system13-13
31Detonation sensor system13-14
41Injector system13-14
44Ignition coil and power transistor unit system13-15
64Alternator FR terminal system13-16
3. INSPECTION PROCEDURE FOR DIAGNOSIS CODES
Code No. 12 Air flow sensor (AFS) systemProbable cause
Range of Check
Engine speed is 500 r/min or more.
Set conditions
Sensor output frequency is 3 Hz or less for 4 seconds.Malfunction of the air flow sensor
Improper connector contact, open circuit or
short-circuited harness wire of the air flow sensor
Malfunction of the engine-ECU
Measure at the air flow sensor con-
nector A-25.
Connect the connector. (Use
the test harness: MB991709)
1. Voltage between 3 and earth
(Engine: Idling)
OK:2.2–3.2 V
2. Voltage between 7 and earth
OK:0–1 V (Engine: idling)
6–9 V (2,000 r/min)
OK
Replace the engine-ECU.1. NG
Check the air flow sensor circuit.
2. NG
Measure at the engine-ECU con-
nector B-59.
Connect the connector.
Voltage between 19 and earth
(Ignition switch: ON)
OK:6–9 V
OK
Check the following connector:
B-59
OK
Check trouble symptom.
NG
Replace the engine-ECU.NG
Check the following connector:
A-25NG
Repair
OK
Check trouble symptom.
NG
NG
Repair
Replace the air flow sensor.

MPI – Troubleshooting13-14
Code No.31 Detonation sensor systemProbable cause
Range of Check
Ignition switch: ON
Excluding 60 seconds after the ignition switch is turned to ON or immediately
after the engine starts.
Engine speed is approx. 5,000 r/min or more
Set conditions
The change in the detonation sensor output voltage (detonation sensor peak voltage
at each 1/2 revolution of the crankshaft) is less than 0.06 V for 200 times in succession.Malfunction of the detonation sensor
Improper connector contact, open circuit or
short-circuited harness wire of the detonation sensor
circuit
Malfunction of the engine-ECU
Measure at the detonation sensor con-
nector A-96.
Disconnect the connector and
measure at the harness side.
Continuity between 2 and earth
OK:ContinuityOKCheck the following connector:
B-62NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between the
engine-ECU and the detonation sensor
connector.OKReplace the detonation sensor.
Check trouble symptom.
NG
Replace the engine-ECU.
NG
Repair
NG
Check the harness wire between the
detonation sensor and earth, and repair
if necessary.
Code No. 41 Injector systemProbable cause
Range of Check
Engine speed is approx. 50–1,000 r/min
The throttle position sensor output voltage is 1.15 V or less.
Set conditions
Surge voltage of injector coil is not detected for 4 seconds.Malfunction of the injector
Improper connector contact, open circuit or
short-circuited harness wire of the injector circuit
Malfunction of the engine-ECU
NG
Check the harness wire between the
resistor and the injector connector, and
repair if necessary.
OK
Check trouble symptom.
OK
Check the injector control circuit.
OK
Measure at the injector connectors
A-53, A-54, A-55, A-56.
Disconnect the connector, and
measure at the harness side.
Voltage between 1 and earth
(Ignition switch: ON)
OK:System voltageNGCheck the following connector:
A-125NG
Repair
Check the injector. (Refer to P.13-34.)
Check the resistor. (Refer to P.13-34.)NG
Replace
OK
Measure at the resistor connector
A-125.
Disconnect the connector, and
measure at the harness side.
Voltage between 3 and earth
(Ignition switch: ON)
OK:System voltageNGCheck the harness wire between the
control relay and the resistor connec-
tor, and repair if necessary.

MPI – Troubleshooting13-15
Code No. 44 Ignition coil and power transistor unit systemProbable cause
Range of Check
Engine speed is approx. 50 – 4,000 r/min.
Engine is not being cranked.
Set conditions
Abnormal engine speed is detected due to misfiring by crank angle sensor. (One
of two coils fails.)Malfunction of the ignition coil
Improper connector contact, open circuit or
short-circuited harness wire of the ignition primary
circuit
Malfunction of the engine-ECU.
NG
Check the harness wire between the ignition coil and ignition switch
connector, and repair if necessary.
2. NG
OK
Replace the engine-ECU.
3. NG
NG
Check the following items.
Check the spark plugs and spark plug cables.
Check the compression pressure.
OK
Check trouble symptom.
OK
Check the following
connectors:
A-110, A-111NG
Repair
NG
Check the harness wire
between the engine-ECU
and ignition coil connec-
tor.NG
Repair
OK
Check trouble symptom.
Check the following
connector:
B-59NG
Repair
OK
Check trouble symptom.
OK
Measure at the ignition coil connectors A-110, A-111.
Disconnect the connector, and measure at the harness.
1. Voltage between 1 and earth (Ignition switch: ON)
OK:System voltage
2. Voltage between 3 and earth (Engine: Cranking)
OK:0.5 – 4.0 V
3. Continuity between 2 and earth
OK:Continuity1. NGCheck the following
connectors:
B-65, B-76NG
Repair
Check the ignition coil. (Refer to Group 16 – Ignition System.)NG
Replace
Check the harness wire between the ignition coil connector and
earth, and repair if necessary.

MPI – Troubleshooting13-22
6. ENGINE-ECU INSPECTION
6-1 TERMINAL VOLTAGES
Engine ECU connector
Terminal
No.Check itemCheck condition (Engine condition)Normal condition
1No.1 injectorWhile engine is idling after having been warmed up,
suddenly depress the accelerator pedal
Momentarily drops
slightlyfrom 1114V
14No.2 injector
suddenly depress the accelerator pedal.slightly from 11 – 14 V.
2No.3 injector
15No.4 injector
3Fuel pressure control
valve
Ignition switch: ONBattery voltage
valve
Engine: Cranking to idling (within about two minutes)0 – 3 V to battery
voltage
4Stepper motor coil (A1)Engine: Immediately after engine has been started
f
or warming up
Changes repeatedly
f
rom battery voltage to
17Stepper motor coil (A2)
for warming upfrom battery voltage to
0 – 6 V and from 0 – 6
V to battery voltage5Stepper motor coil (B1)V to battery voltage.
18Stepper motor coil (B2)
6Secondary air control
solenoid valveIgnition switch: ONBattery voltage
8Fuel pump relayIgnition switch: ONBattery voltage
Engine: Idling0 – 3 V
10Power transistor unit
(A)Engine speed: 3,000 r/min0.3 – 3.0 V
23Power transistor unit
(B)
11Wastegate solenoid
valve
Ignition switch: ONBattery voltage
valve
Engine: At idle after having been warmed up (when
premium gasoline is used)0 – 3 V
12Power supplyIgnition switch: ONBattery voltage
25
19Air flow sensor reset
signal
Engine: Idling0 – 1 V
signal
Engine speed: 3,000 r/min6 – 9 V
20Fan motor relay (HI)Fan not operating (coolant temperature: 90C or
below)Battery voltage
Fan at high speed (coolant temperature: 105C or
above)0 – 3 V

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 – Troubleshooting13-27

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 – Troubleshooting13-29

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