1998 MITSUBISHI LANCER EVOLUTION IV air condition

ENGINE – Engine Adjustments11-5
2. AUTO TENSIONER CHECK
(1) Stop the engine from the idle speed and check that the
belt rests within the auto tensioner pulley width.
(2) Remove the drive belt.
(For the removal of the drive belt, refer to P.11-9.)
(3) Fit a spinner handle or similar tool into the tool mounting
hole of the auto tensioner and turn the tensioner clockwise
and counterclockwise to ensure that it does not bind.
(4) If step (1) or (3), or both, have been checked abnormally,
replace the auto tensioner.
(5) Reinstall the drive belt.
3. LASH ADJUSTER CHECK
NOTE
If an unusual knocking noise can be heard immediately after
the engine has started or while it is running and if that is
probably attributable to the lash adjuster, make the following
checks.
(1) Check the engine oil and add or change oil as necessary.
NOTE
(1) If the engine oil level is low, air is taken in through
the oil screen, entering the oil passage.
(2) If the oil level is too high, the cranks agitate oil causing
oil to trap a large amount of air.
(3) Air does not easily separate from a deteriorated oil
that can contain an increased amount of air.
When air trapped in oil for these reasons gets into the
high-pressure chamber of the lash adjuster, the air in
the high-pressure chamber is compressed to shrink the
lash adjuster excessively while the valve is opening,
resulting in an unusual noise occurring. This is the same
symptom developing when the valve clearance is adjusted
to an excessive value.
The problem in this case is gone when air is released
from the lash adjuster.
(2) Start the engine and carry out several cycles (10 or less)
of mild racing*.
If the noise is gone after racing, it indicates that air has
been released from the high-pressure chamber of the
lash adjuster, restoring the lash adjuster to normal
operating conditions.
*: Gradually (extending over a 30-sec. period) increase
the engine speed from idle speed to 3,000 r/min and
then reduce it down to the idle speed gradually
(extending over a 30-sec. period).
NOTE
(1) If the vehicle is parked on a slope for a long time,
the amount of oil in the lash adjuster will decrease,
causing air to get into the high-pressure chamber
when the engine is started.
(2) After the vehicle has been parked for a long time,
oil drains out of the oil passage and it takes a long
time for the oil to reach the lash adjuster. This can
cause air to get into the high-pressure chamber.
Tool mounting hole
Good
MAX
MIN
High-pressure
chamber

MPI – Troubleshooting13-7
1-3 ERASING DIAGNOSIS CODES
(1) Turn the ignition switch to OFF.
(2) After disconnecting the battery cable from the battery (–) terminal for 10 seconds or more, reconnect
the cable.
(3) After the engine has warmed up, run it at idle for about 15 minutes.
1-4 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 sensor (AFS)(1) 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
sensor (TPS)No increase in fuel injection amount during acceleration due to the throttle position sensor
signal.
Engine coolant
temperature sensorControls 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.)
Camshaft position
sensor(1) Injects 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.)
(2) Lets the fan motor (radiator and condensor) run at high speed.
Barometric pressure
sensorControls as if the barometric pressure is 101 kPa {760 mmHg}.
Detonation sensorSwitches the ignition timing from ignition timing for super petrol to ignition timing for standard
petrol.
Ignition coil, power
transistorCuts 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)
Misfire
(Evolution-V only)Cuts off the fuel to the misfiring cylinder if a misfire that could damage the catalyst is detected.

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 – Troubleshooting13-9
Code No. 13 Intake air 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 intake air temperature
of –45C or less) for 4 seconds.
or
Sensor output voltage is 0.2V or less (corresponding to an intake air temperature
of 125C or more) for 4 seconds.Malfunction of the intake air temperature sensor
Improper connector contact, open circuit or
short-circuited harness wire of the intake air
temperature sensor circuit
Malfunction of the engine-ECU
OK
Check trouble symptom.
Check the intake air temperature sen-
sor. (Refer to P.13-32.)NGReplace air flow sensor.
OK
Measure at the air flow sensor connec-
tor A-25.
Disconnect the connector, and
measure at the harness side.
Voltage between 6 and earth
(Ignition switch: ON)
OK:4.5–4.9 V
Continuity between 5 and earth
OK:ContinuityNGCheck the following connector:
C-62NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire between the
engine-ECU and the intake air temper-
ature sensor connector.NG
Repair
OK
Replace the engine-ECU.
OK
Check the following connector:
A-25NG
Repair
NG
Code No. 14 Throttle position sensor (TPS) 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
The sensor output voltage is 0.2 V or less for 4 seconds.Malfunction of the throttle position sensor
Improper connector contact, open circuit or
short-circuited harness wire of the throttle position
sensor circuit
Improper “ON” state of idle position switch
Short circuit of the idle position switch signal line
Malfunction of the engine-ECU
Check the throttle position sensor.NG
Replace
OK
Measure at the throttle position sensor
connector A-16.
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 4 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 throttle position
sensor connector.NG
Repair
OK
Replace the engine-ECU. OK
Check the throttle position sensor out-
put circuit.

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 circuit 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.
OK
Check trouble symptom.
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-38NG OK
Repair
NG

MPI – Troubleshooting13-11
Code No. 22 Crank angle sensor systemProbable cause
Range of Check
Engine is cranking.
Set conditions
Sensor output voltage does not change for 4 seconds (no pulse signal input.)Malfunction of the crank angle sensor
Improper connector contact, open circuit or
short-circuited harness wire of the crank angle sensor
Malfunction of the engine-ECU
Measure at the crank angle sensor connector A-51.
Connect the connector. (Use the test harness: MD998478.)
Voltage between 2 (black clip) and earth (Engine: cranking)
OK:0.4–4.0 V
Voltage between 2 (black clip) and earth (Engine: idling)
OK:1.5–2.5 V
NGOKReplace the engine-ECU.
Measure at the crank angle sensor connector A-51.
Disconnect the connector, and measure at the harness side.
1. Voltage between 3 and earth (Ignition switch: ON)
OK:System voltage
2. Voltage between 2 and earth (Ignition switch: ON)
OK:4.8–5.2 V
3. Continuity between 1 and earth
OK:Continuity
OK
Check the following con-
nector: A-51NG
Repair
OK
Check trouble symptom.
NG
Replace the crank angle sensor.1. NG
Check the harness wire between the crank angle sensor and the
control relay connector, and repair if necessary.
2. NGCheck the following con-
nector: B-62NG
Repair
OK3. NG
Check trouble symptom.
NG
Check the harness wire
between the engine-ECU and
the crank angle sensor
connector.NG
Repair
OK
Replace the engine-ECU.
Check the harness wire between the crank angle sensor and the
earth, and repair if necessary.
Code No. 23 Camshaft position sensor systemProbable cause
Range of Check
Ignition switch: ON
Engine speed is approx. 50 r/min or more.
Set conditions
Sensor output voltage does not change for 4 seconds (no pulse signal input.)Malfunction of the camshaft position sensor
Improper connector contact, open circuit or
short-circuited harness wire of the camshaft position
sensor circuit
Malfunction of the engine-ECU
Measure at the camshaft position sensor connector A-97.
Connect the connector.
Voltage between 2 and earth (Engine: cranking)
OK:0.4–3.0 V
Voltage between 2 and earth (Engine: idling)
OK:0.5–2.0 VOKReplace the engine-ECU.
NG
Measure at the camshaft position sensor connector A-97.
Disconnect the connector, and measure at the harness side.
1. Voltage between 3 and earth (Ignition switch: ON)
OK:System voltage
2. Voltage between 2 and earth (Ignition switch: ON)
OK:4.8–5.2 V
3. Continuity between 1 and earth
OK:Continuity1. NGCheck the harness wire between the camshaft position sensor
and the control relay connector, and repair if necessary.
2. NGCheck the following con-
nector: B-62NG
Repair
OK
Check trouble symptom.
NG
Check the harness wire
between the engine-ECU and
the camshaft position sensor
connector.NG
Repair
OK
Replace the engine-ECU. 3. NG
Check the harness wire between the camshaft position sensor
and the earth, and repair if necessary.
OK
Check the following con-
nector: A-97NG
Repair
OK
Check trouble symptom.
NG
Replace the camshaft position sensor.

MPI – Troubleshooting13-12
Code No. 24 Vehicles speed 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.
Idle position switch: OFF
Engine speed is 3,000 r/min or more.
Driving under high engine load conditions.
Set conditions
Sensor output voltage does not change for 4 seconds (no pulse signal input).Malfunction of the vehicle speed sensor
Improper connector contact, open circuit or
short-circuited harness wire of the vehicle speed
sensor circuit
Malfunction of the engine-ECU
OK
Check the ignition switch. (Refer to GROUP 54 – Ignition Switch.)
2. NG
OK
Replace the engine-ECU.
3. NG
OK
Replace the engine-ECU.
NG
Check the harness wire
between the engine-ECU
and the vehicle speed
sensor connector.NG
Repair
OK
Check trouble symptom.
OK
Check the following
connectors:
A-19, B-62NG
Repair
NG
Check the harness wire
between the engine-ECU
and the vehicle speed
sensor connector.NG
Repair
OK
Check trouble symptom.
Check the following
connector:
B-62NG
Repair
NG
Check the harness wire
between the vehicle
speed sensor and ignition
switch connector.NG
Repair
OK
Check trouble symptom.
OK
Measure at the vehicle speed sensor connector A-19.
Disconnect the connector, and measure at the harness side.
1. Voltage between 1 and earth (Ignition switch: ON)
OK:System voltage
2. Voltage between 3 and earth (Ignition switch: ON)
OK:4.8 – 5.2 V
3. Continuity between 2 and earth
OK:Continuity1. NGCheck the following
connectors:
B-64, B-74, B-76NG
Repair
Check the vehicle speed sensor. (Refer to GROUP 54 – Combina-
tion Meters.)NG
Replace
Check the harness wire between the vehicle speed sensor and
the earth, and repair if necessary.

MPI – Troubleshooting13-13
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 {855 mmHg} or more) for 4 seconds.
or
Sensor output voltage is 0.2 V or less (corresponding to a barometric pressure
of 53 kPa {40 mmHg} or less) for 4 seconds.Malfunction of the barometric pressure sensor
Improper connector contact, open circuit or
short-circuited harness wire of the barometric pressure
sensor circuit
Malfunction of the engine-ECU
OK
Replace the air flow sensor.
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)
3.2–3.8 V
(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.Check the harness wire between
the engine-ECU and the baromet-
ric pressure sensor connector.NG
Repair
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)
3.2–3.8 V
(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 connec-
tors:
A-25, B-62
OK
Check trouble symptom.
NG
Replace the engine-ECU.NG
Repair OKNG