ECU MITSUBISHI LANCER EVOLUTION VI 1999 Owner's Manual

MPI – Troubleshooting13-14
Code No. 25 Barometric pressure 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.
Set conditions

Sensor output voltage is 4.5 V or more (corresponding to a barometric pressure
of 114 kPa or more) for 4 seconds.
or

Sensor output voltage is 0.2 V or less (corresponding to a barometric pressure
of 5.33 kPa or less) for 4 seconds.
Malfunction of the barometric pressure sensor

Improper connector contact, open or short-circuited
harness wire of the barometric pressure sensor circuit

Malfunction of the engine-ECU
Measure at the air flow sensor con-
nector A-25.

Connect the connector. (Use
the test harness: MB991709)

Voltage between 2 and earth
(Ignition switch: ON)
OK:3.7–4.3 V (Altitude: 0 m)
3.2–3.8V (Altitude:
1,200 m)NGMeasure at the air flow sensor con-
nector A-25.

Disconnect the connector, and
measure at the harness side.

Voltage between 1 and earth
(Ignition switch: ON)
OK:4.8–5.2 V

Continuity between 5 and earth
OK:ContinuityNGCheck the following connector:
B-62NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector.NG
Repair
OK
Replace the engine-ECU.
OK
Check the following connector:
A-25NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector.NG
Repair
OK
Replace the air flow sensor.
OK
Measure at the engine-ECU con-
nector B-62.

Connect the connector.

Voltage between 85 and earth
(Ignition switch: ON)
OK:3.7–4.3 V (Altitude: 0 m)
3.2–3.8V (Altitude:
1,200 m)NGCheck the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector, and
repair if necessary.
Check the following connector:
A-25, B-62
OK
Check trouble symptom.
NG
Replace the engine-ECU.NG
Repair OK

MPI – Troubleshooting13-15
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 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.

Actuator test by MUT-II is not carried out.
Set conditions

Surge voltage of injector coil is not detected for 4 seconds.
Malfunction of the injector

Improper connector contact, open or short-circuited
harness wire of the injector circuit

Malfunction of the engine-ECU
OK
Check trouble symptom.NGCheck the harness wire between the
resistor and the injector connector, and
repair if necessary.
Check the injector control circuit.
(Refer to P.13-55, INSPECTION PRO-
CEDURE 50.)OK
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
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 connector,
and repair if necessary.
Check the injector. (Refer to P.13-34.)*
Check the resistor. (Refer to P.13-34.)*NG
Replace
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

MPI – Troubleshooting13-16
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 cranking.
Set conditions

Abnormal rotation due to misfire is detected by crank angle sensor (Either one
of coils fails).
Malfunction of the ignition coil

Improper connector contact, open or short-circuited
harness wire of the ignition primary circuit

Malfunction of the engine-ECU
OK
OK
Check trouble symptom.
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 the 2 and earth
OK: Continuity1. NGCheck the following connectors:
B-65, B-76OKCheck trouble symptom.
NG
Check the harness wire between the
ignition coil and ignition switch connec-
tor, and repair if necessary.
2. NGCheck the following connector: B-59NG
Repair
NG
Check the harness wire between the
engine-ECU and ignition coil connector.OKReplace the engine-ECU.
NG
Repair
3. NG
Check the harness wire between the
ignition coil connector and earth, and
repair if necessary.
Check the following connectors:
A-110, A-111NG
Repair
Check trouble symptom.
NG
Check the following items.

Check the spark plugs, spark plug
cables.

Check the compression pressure.
NG
Repair
Check the ignition coil. (Refer to
GROUP 16 – IGNITION SYSTEM.)NG
Replace
OK
OK

MPI – Troubleshooting13-17
Code No. 64 Alternator FR terminal systemProbable cause
Range of Check

Engine speed is approx. 50 r/min or more
Set Conditions

The input voltage from the alternator FR terminal is higher than 4.5 V for 20 seconds.
Open circuit in alternator FR terminal circuit

Malfunction of the engine-ECU
Measure at the alternator connector A-05.

Connect the connector. (Use the test harness: MB991519.)

Voltage between 4 (blue clip) and earth
(Engine: Idling)
(Radiator fan: Stopped)
(Headlamp: OFF → ON)
(Brake lamp: OFF → ON)
(Rear window defogger switch: OFF → ON)
OK:Voltage drops 0.2 to 3.5 VOKReplace the engine-ECU.
NG
Measure at the alternator connector A-05.

Disconnect the connector, and measure at the harness side.

Voltage between 4 and earth
(Ignition switch: ON)
OK:4.8 – 5.2 VNGCheck the following
connectors: B-60, A-88NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire
between the engine-ECU
and the alternator con-
nector.NG
Repair
OK
Replace the engine-ECU.
OK
Check the following connector: A-05NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between the engine-ECU and the alternator
connector.NG
Repair
OK
Replace the alternator.

MPI – Troubleshooting13-18
INSPECTION CHART FOR TROUBLE SYMPTOMS
Trouble symptomInspection
procedure
No.Reference page
Communication
with MUT-IIis
Communication with all systems is impossible.113-20
with MUT-II is
impossible.
Communication with engine-ECU only is impossible.213-20
Engine warning
lamp and
related parts
The engine warning lamp does not illuminate right after the
ignition switch is turned to the ON position.313-21
related partsThe engine warning lamp remains illuminating and never goes
out.413-21
StartingNo initial combustion (starting impossible)513-22
Initial combustion but no complete combustion
(starting impossible)613-23
Long time to start (improper starting)713-24
Idling stability
(Improper idling)
Unstable idling (Rough idling, hunting)813-25
(Improper idling)
Idling speed is high. (Improper idling speed)913-26
Idling speed is low. (Improper idling speed)1013-27
Idling stability
(Engine stalls)
When the engine is cold, it stalls at idling. (Die out)1113-28
(Engine stalls)
When the engine is hot, it stalls at idling. (Die out)1213-29
The engine stalls when starting the car. (Pass out)1313-30
The engine stalls when decelerating.1413-30
DrivingHesitation, sag or stumble1513-31
The feeling of impact or vibration when accelerating1613-31
The feeling of impact or vibration when decelerating1713-32
Poor acceleration1813-32
Surge1913-33
Knocking2013-33
Dieseling2113-33
Too high CO and HC concentration when idling2213-34
Low alternator output voltage (approx. 12.3 V)2313-35

MPI – Troubleshooting13-20
INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS
INSPECTION PROCEDURE 1
Communication with MUT-II is impossible.
(Communication with all systems is impossible.)
Probable cause
The cause is probably a defect in the power supply system (including earth) for the
diagnosis line.
Malfunction of the diagnosis connector

Malfunction of the harness wire
Measure at the diagnostic connector
B-22.

Voltage between 16 and earth
OK:System voltageNGCheck the following connectors:
B-49, B-75, B-73
B-73, B-80NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between the
power supply and diagnostic connector,
and repair if necessary.OK
Measure at the diagnostic connector
B-22.

Continuity between 4 and earth

Continuity between 5 and earth
OK:ContinuityNGCheck the earth wire, and repair if nec-
essary.
OK
Replace the MUT-II.
INSPECTION PROCEDURE 2
MUT-II communication with engine-ECU is impossible.
Probable cause
One of the following causes may be suspected.

No power supply to engine-ECU.

Defective earth circuit of engine-ECU.

Defective engine-ECU.

Improper communication line between engine-ECU and MUT-II
Malfunction of engine-ECU power supply circuit

Malfunction of engine-ECU

Open circuit between immobilizer-ECU and diagnosis
connector
OK
Check the engine-ECU power supply and earth circuit.
(Refer to P.13-53, INSPECTION PROCEDURE 45.)
NG
Check the harness wire between engine-ECU and diagnosis con-
nector.NG
Repair
OK
Check trouble symptom.
Check the following connectors:
B-22, B-65, B-32, B-61NG
Repair

MPI – Troubleshooting13-21
INSPECTION PROCEDURE 3
The engine warning lamp does not illuminate right after
the ignition switch is turned to the ON position.
Probable cause
For checking for burnt-out bulb, the engine-ECU causes the engine warning lamp
to illuminate for five seconds immediately after the ignition switch is turned to ON.
If the engine warning lamp does not illuminate immediately after the ignition switch
is turned to ON, one of the malfunctions listed at right has probably occurred.
Burnt-out bulb of the engine warning lamp

Defective engine warning lamp circuit

Malfunction of the engine-ECU
MUT-II Data list
16 engine-ECU power supply voltage (Refer to P.13-57)NGCheck the engine-ECU power supply and earth circuit.
(Refer to P.13-53, INSPECTION PROCEDURE 45.)
OK
Measure at the engine-ECU connector B-60.

Disconnect the connector, and measure at the harness side.

Earth the terminal No.36. (Ignition switch: ON)
OK:The engine warning lamp illuminates.OKCheck the following
connector: B-60NG
Repair
OK
Check trouble symptom.
NG
Replace the engine-ECU.
NG
Check for burnt-out bulb.NG
Replace
OK
Measure at the combination meter connector B-08.

Disconnect the connector, and measure at the harness side.

Voltage between 42 and earth (Ignition switch: ON)
OK:System voltageNGCheck the engine warning lamp power supply circuit, and repair
if necessary.
OK
Check the following connectors:
B-08, B-65, B-60NG
Repair
OK
Check trouble symptom.NGCheck the harness wire between combination meter and engine-
ECU connector, and repair if necessary.
INSPECTION PROCEDURE 4
The engine warning lamp remains illuminating and never
goes out.
Probable cause
In cases such as the above, the cause is probably that the engine-ECU is detecting
a problem in a sensor or actuator, or that one of the malfunctions listed at right has
occurred.
Short-circuit between the engine warning lamp and
engine-ECU

Malfunction of the engine-ECU
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
No
Measure at the combination meter connector B-08.

Disconnect the connector, and measure at the harness side.

Disconnect the engine-ECU connector

Continuity between 53 and earth
OK:No continuityNGCheck the harness wire between combination meter and engine-
ECU connector, and repair if necessary.
OK
Replace the engine-ECU.

MPI – Troubleshooting13-22
INSPECTION PROCEDURE 5
No initial combustion (starting impossible)
Probable cause
In cases such as the above, the cause is probably that a spark plug is defective,
or that the supply of fuel to the combustion chamber is defective.
In addition, foreign materials (water, kerosene, etc.) may be mixed with the fuel.
Malfunction of the ignition system

Malfunction of the fuel pump system

Malfunction of the injectors

Malfunction of the engine-ECU

Foreign materials in fuel
Check system voltage when cranking.
OK:8 V or higherNGCheck the battery.
OK
MUT-II: Inspection of no initial combustion.
(Refer to P.13-47, INSPECTION PROCEDURE 37.)
OK
Can any sound be heard from the injectors when cranking (check
using a soundscope)?NGCheck the injector system. (Refer to P.13-15, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)
OK
Ignition system: Inspection of no initial combustion.
(Refer to P.13-47, INSPECTION PROCEDURE 38.)
OK
Check the following items.

Check the ignition coil, spark plugs, spark plug cables.

Check if the injectors are clogged.

Check if foreign materials (water, alcohol, etc.) got into fuel.

Check the compression pressure.

MPI – Troubleshooting13-23
INSPECTION PROCEDURE 6
Initial combustion but no complete combustion
(starting impossible)
Probable cause
In such cases as the above, the cause is probably that the spark plugs are generating
sparks but the sparks are weak, or the initial mixture for starting is not appropriate.
Malfunction of the ignition system

Malfunction of the injector system

Foreign materials in fuel

Poor compression

Malfunction of the engine-ECU
Check system voltage when cranking.
OK:8 V or higherNGCheck the battery.
OK
MUT-II: Check if uncompleted combustion occurs.
(Refer to P.13-48, INSPECTION PROCEDURE 39.)
OK
Can any sound be heard from the injectors when cranking (check
using a soundscope)?NGCheck the injector system, (Refer to P.13-15, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)
OK
Is starting good if the engine is cranked with the accelerator pedal
slightly depressed?Ye sCheck ISC servo for op-
eration sound. NGCheck the ISC servo sys-
tem. (Refer to P.13-44, IN-
SPECTION PROCE-
DURE 33.)
OK

Clean the throttle valve area.

Adjust the fixed SAS. (Refer to P.13-30.)*
No
Check the ignition timing when cranking.
OK:Approx. 5BTDCNGCheck that the crank angle sensor and the timing belt cover are
installed properly.
OK
Check the following items.

Check the ignition coil, spark plugs, spark plug cables.

Check the injectors for clogging and leakage.

Check the compression pressure.

Check fuel lines for clogging.

Check if foreign materials (water, alcohol, etc.) got into fuel.
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

MPI – Troubleshooting13-29
INSPECTION PROCEDURE 12
When the engine is hot, it stalls at idling. (Die out)
Probable cause
In such cases as the above, the cause is probably that ignition system, air/fuel mixture,
idle speed control (ISC) or compression pressure is defective.
In addition, if the engine suddenly stalls, the cause may also be a defective connector
contact.
Malfunction of the ignition system

Malfunction of air-fuel ratio control system

Malfunction of the ISC servo system

Drawing air into intake system

Improper connector contact

Backflow of secondary air to the intake system
Were the battery terminals disconnected recently?Ye sAfter warming-up, let the engine run at idling for about 10 minutes.
No
MUT-II Diagnosis code
Are diagnosis codes displayed?Ye sRefer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
No
Check the ISC servo for operation sound.NGCheck the ISC servo system.
(Refer to P.13-44, INSPECTION PROCEDURE 33.)
OK
Check the injector for operation sound.NGCheck the injector system. (Refer to P.13-15, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)
OK
Does the engine stall right after the accelerator pedal is released?Ye sClean the throttle valve
area.Adjust the fixed SAS.
(Refer to P.13-30.)*
No
Does the engine stall easily again?NoWhile carrying out an intermittent malfunction simulation test (Refer
to GROUP 00 – Points to Note for Intermittent Malfunctions.), check
for sudden changes in the signals shown below.

Crank angle sensor signal

Injector drive signal

Fuel pump drive signal

Air flow sensor signal
Secondary ignition signal

Engine-ECU power supply
voltage
Ye s
MUT-II: Engine stalling inspection when the engine is warm and
idling. (Refer to P.13-50, INSPECTION PROCEDURE 42.)
OK
Check the ignition timing.
(Refer to GROUP 11 – ENGINE ADJUSTMENTS.)*NGCheck that the crank angle sensor and the timing belt cover are
installed properly.
OK
Check the following items.

Check the ignition coil, spark plugs, spark plug cables.

Check the secondary air supply system. (Ensure that there is no backflow of secondary air into the intake system.)

Check if the injectors are clogged.

Check the compression pressure.

Check if foreign materials (water, alcohol, etc.) got into fuel.
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).