1999 MITSUBISHI LANCER EVOLUTION VI engine coolant

MPI – Troubleshooting13-6
TROUBLESHOOTING
DIAGNOSIS TROUBLESHOOTING FLOW
Refer to GROUP 00 – How to Use Troubleshooting/Inspection
Service Points.
DIAGNOSIS FUNCTION
ENGINE WARNING LAMP (CHECK ENGINE LAMP)
If an abnormality occurs in any of the following items related
to the Multipoint Fuel Injection (MPI) system, the engine
warning lamp will illuminate.
If the lamp remains illuminated or if the lamp illuminates while
the engine is running, check the diagnosis code output.
Engine warning lamp inspection items
Engine-ECU
Air flow sensor
Intake air temperature sensor
Throttle position sensor
Engine coolant temperature sensor
Crank angle sensor
Camshaft position sensor
Barometric pressure sensor
Detonation sensor
Injector
Ignition coil, power transister unit
METHOD OF READING AND ERASING DIAGNOSIS
CODES
Refer to GROUP 00 – How to Use Troubleshooting/Inspection
Service Points.
INSPECTION USING MUT-II DATA LIST AND
ACTUATOR TESTING
1. Carry out inspection by connecting the MUT-II.
If there is an abnormality, check and repair the chassis
harnesses and components.
2. After repairing, check that the abnormal input and output
have returned to normal as a result of the repairs.
3. Erase the diagnosis code memory.
4. Remove the MUT-II and carry out a road test to confirm
that the problem has disappeared.
Engine warning lamp
(check engine lamp)

MPI – Troubleshooting13-7
FAIL-SAFE FUNCTION REFERENCE TABLE
When the main sensor malfunctions are detected by the diagnosis function, the vehicle is controlled
by means of the pre-set control logic to maintain safe conditions for driving.
Malfunctioning itemControl contents during malfunction
Air flow sensor1. Uses the throttle position sensor signal and engine speed signal (crank angle sensor
signal) to take reading of the basic injector drive time and basic ignition timing from
the pre-set mapping.
2. Fixes the ISC servo in the appointed position so idle control is not performed.
Intake air temperature
sensorControls as if the intake air temperature is 25C.
Throttle position
sensorNo increase in fuel injection amount during acceleration due to the throttle position sensor
signal.
Engine coolant
temperature sensor1. Controls as if the engine coolant temperature is 80C.
(This condition is maintained until the ignition switch is turned off even when the
sensor signal returns normal.)
2. Lets the fan motor (radiator and condenser) run at high speed.
Camshaft position
sensorInjects fuel to all cylinders simultaneously for 4 seconds.
(However, after the ignition switch is turned to ON, the No. 1 cylinder top dead centre is not
detected at all.)
Barometric pressure
sensorControls as if the barometric pressure is 101 kPa.
Detonation sensorSwitches the ignition timing from ignition timing for super petrol to ignition timing for standard
petrol.
Ignition coil, power
transistor unitCuts off the fuel supply to cylinders with an abnormal ignition.
Alternator FR terminalDoes not control the output of the alternator according to an electrical load. (works as a
normal alternator)

MPI – Troubleshooting13-8
3. INSPECTION CHART FOR DIAGNOSIS CODES
Code No.Diagnosis itemReference page
12Air flow sensor system13-8
13Intake air temperature sensor system13-9
14Throttle position sensor system13-9
21Engine coolant temperature sensor system13-10
22Crank angle sensor system13-11
23Camshaft position sensor system13-12
24Vehicle speed sensor system13-13
25Barometric pressure sensor system13-14
31Detonation sensor system13-15
41Injector system13-15
44Ignition coil and power transistor unit system13-16
64Alternator FR terminal system13-17
INSPECTION PROCEDURE FOR DIAGNOSIS CODES
Code No. 12 Air flow sensor 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 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.
(Refer to P.13-55, INSPECTION
PROCEDURE 48.)
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 – Troubleshooting13-10
Code No. 21 Engine coolant temperature 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 4.6 V or more (corresponding to an engine coolant
temperature of –45C or less) for 4 seconds.
or

Sensor output voltage is 0.1 V or less (corresponding to an engine coolant
temperature of 140C or more) for 4 seconds.
Malfunction of the engine coolant temperature sensor

Improper connector contact, open or short-circuited
harness wire of the engine coolant temperature sensor
circuit

Malfunction of the engine-ECU
Range of Check

Ignition switch: ON

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

The sensor output voltage increases from 1.6 V or less (corresponding to an
engine coolant temperature of 40C or more) to 1.6 V or more (corresponding
to an engine coolant temperature of 40C or less).

After this, the sensor output voltage is 1.6 V or more for 5 minutes.
Check the engine coolant temperature
sensor. (Refer to P.13-32.)*NG
Replace
OK
Measure at the engine coolant temper-
ature sensor connector A-38.

Disconnect the connector, and
measure at the harness side.

Voltage between 1 and earth
(Ignition switch: ON)
OK:4.5–4.9 V

Continuity between 2 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 engine coolant
temperature sensor connector.NG
Repair
OK
Replace the engine-ECU.
Check the following connector:
A-38OKCheck trouble symptom.
NG
Replace the engine-ECU.
NG
RepairOK
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

MPI – Troubleshooting13-26
INSPECTION PROCEDURE 9
Idling speed is high. (Improper idling speed)
Probable cause
In such cases as the above, the cause is probably that the intake air volume during
idling is too great.
Malfunction of the ISC servo system

Malfunction of the throttle body
OK
MUT-II Data list
26 Idle position switch (Refer to P.13-58.)NGCheck the idle position switch system.
(Refer to P.13-38, INSPECTION PROCEDURE 26.)
No
Check the ISC servo for operation sound.NGCheck the ISC servo system.
(Refer to P.13-44, INSPECTION PROCEDURE 33.)
OK
MUT-II Data list
21 Engine coolant temperature sensor (Refer to P.13-57.)NGCheck the engine coolant temperature sensor system.
(Refer to P.13-10, INSPECTION PROCEDURE FOR DIAGNOSIS
CODE 21.)
OK
MUT-II Data list
28 A/C switch (Refer to P.13-58.)NGCheck the A/C switch and A/C relay system.
(Refer to P.13-39, INSPECTION PROCEDURE 29.)
OK
Basic idle speed adjustment (Refer to P.13-30.)*
Check trouble symptom.NGClean the throttle valve area.
Adjust the fixed SAS. (Refer to P.13-30.)*
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

MPI – Troubleshooting13-27
INSPECTION PROCEDURE 10
Idling speed is low. (Improper idling speed)
Probable cause
In cases such as the above, the cause is probably that the intake air volume during
idling is too small.
Malfunction of the ISC servo system

Malfunction of the throttle body
MUT-II Self-Diag 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
MUT-II Data list
26 Idle position switch (Refer to P.13-58.)NGCheck the idle position switch system.
(Refer to P.13-38, INSPECTION PROCEDURE 26.)
OK
MUT-II Data list
21 Engine coolant temperature sensor (Refer to P.13-57.)NGCheck the engine coolant temperature sensor system.
(Refer to P.13-10, INSPECTION PROCEDURE FOR DIAGNOSIS
CODE 21.)
OK
Basic idle speed adjustment (Refer to P.13-30.)*
Check trouble symptom.NGClean the throttle valve area.
Adjust the fixed SAS. (Refer to P.13-30.)*
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

MPI – Troubleshooting13-28
INSPECTION PROCEDURE 11
When the engine is cold, it stalls at idling. (Die out)
Probable cause
In such cases as the above, the cause is probably that the air/fuel mixture is inappropriate
when the engine is cold, or that the intake air volume is insufficient.
Malfunction of the ISC servo system

Malfunction of the throttle body

Malfunction of the injector system

Malfunction of the ignition system
Were the battery terminals disconnected recently?Ye sAfter warming-up, let the engine run at idling for about 10 minutes.
No
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
OK
Check the fuel pressure. (Refer to P.13-30.)*
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 compression pressure.

Check the engine oil viscosity.
OK
MUT-II Data list
26 Idle position switch (Refer to P.13-58.)NGCheck the idle position switch system.
(Refer to P.13-38, INSPECTION PROCEDURE 26.)
OK
Check the injector for operation sound.NGCheck the injector system. (Refer to P.13-15, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)
Ye s
Check the ISC servo for operation sound.NGCheck the ISC servo system.
(Refer to P.13-44, INSPECTION PROCEDURE 33.)
No
Is engine-idling stable after the warming-up?NoCheck for unstable idling (Rough idling, hunting).
(Refer to P.13-25, INSPECTION PROCEDURE 8.)
No
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.)*
OK
MUT-II Data list
21 Engine coolant temperature sensor (Refer to P.13-57.)NGCheck the engine coolant temperature sensor system.
(Refer to P.13-10, INSPECTION PROCEDURE FOR DIAGNOSIS
CODE 21.)
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

MPI – Troubleshooting13-34
INSPECTION PROCEDURE 22
Too high CO and HC concentration when idling
Probable cause
Abnormal air-fuel ratio is suspected.
Malfunction of the air-fuel ratio control system

Deteriorated catalyst
Check trouble symptom.
No
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
MUT-II Data list
21 Engine coolant temperature sensor. (Refer to P.13-57.)NGCheck the engine coolant temperature sensor system.
(Refer to P.13-10, INSPECTION PROCEDURE FOR DIAGNOSIS
CODE 21.)
OK
MUT-II Data list
13 Intake air temperature sensor (Refer to P.13-56.)NGCheck the intake air temperature sensor system. (Refer to P.13-9,
INSPECTION PROCEDURE FOR DIAGNOSIS CODE 13.)
OK
MUT-II Data list
25 Barometric pressure sensor (Refer to P.13-58.)NGCheck the barometric pressure sensor system. (Refer to P.13-14,
INSPECTION PROCEDURE FOR DIAGNOSIS CODE 25.)
OK
MUT-II Data list
11 Oxygen sensor
OK:600–1,000 mV when racing suddenlyNGCheck the oxygen sensor system. (Refer to P.13-15, INSPECTION
PROCEDURE FOR DIAGNOSIS CODE 31.)
OK
MUT-II Data list
11 Oxygen sensor
OK:Repeat 0–400 mV and 600–1,000 mV alternately when
idling.OK
NG
Check the fuel pressure. (Refer to P.13-30.)*
OK
NG
Check the following items.

Check the injectors for operation sound.

Check the injectors for fuel leakage.

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

Check the compression pressure.

Check the positive crankcase ventilation system.

Check the evaporative emission control system.
Check the trouble symptom.
NG
Replace the catalytic converter.
Replace the oxygen sensor.
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).