ENGINE MANAGEMENT
Mitsubishi Lancer CA /CB 1.5 SOHC (4G15 Engine) 1988 To 1992

The 1988-92 Mitsubishi CA and CB Lancers use the 1.5 litre 4G15 SOHC engine, fitted with Multipoint Injection (MPI), monitored and controlled by an Electronic Control Unit (ECU) located behind the left hand kick panel.
The CA and CB Lancers use different sensors, connectors and terminal numbering sequences, although the circuitry and operation are the same. Where CB model terminal number is different from CA models, the CB model number appears in brackets [ ].

TUNE-UP PROCEDURES

Idle Speed
a. Ensure that the front wheels are in the straight ahead position and the transmission is in Neutral (auto. trans. in Park). Start the engine and bring to normal operating temperature (cooling fan ON). Turn lights, cooling fan and all accessories OFF. Check the ignition timing and adjust if necessary .
b. Turn the ignition OFF and loosen the accelerator cable. Disconnect the Throttle Position Sensor (TPS) connector and connect a digital voltmeter between the sensor output terminal 2 and the sensor earth terminal 3 [4]. Turn the ignition ON (do not start the engine) and move the idle speed control plunger to the fast idle position. Maintain this position for approximately 15 seconds before returning the plunger to the initial position. The voltmeter should indicate 0.9 V.
c. Turn the ignition OFF, disconnect the idle speed control servo connector and loosen the fixed Speed Adjusting Screw (SAS). With the idle speed control plunger in the initial position, connect a tachometer (using a paper clip or similar) to the suppression capacitor connector (CA) (white wire) or noise filter (CB) (white wire) (Tune & Code Access Diagrams). Start the engine and allow to idle and check the idle speed.
d. If required, turn the idle speed control adjustment screw to set the idle speed to specification (Tune & Code Access Diagrams). Tighten the fixed SAS screw until the engine speed increases, loosen the screw until the engine speed does not decrease further (touch-point), then loosen the screw a further 1/2 turn from the touch- point.
Transmission

Spark Plug

Gap

Idle Speed

Manual Transmission

WR 7 DC

0.80 mm

650 - 750 rpm

Automatic Transmission

WR 7 DC

0.80 mm

650 - 750 rpm rpm (Transmission in Park or Neutral)

Ignition Timing
a. Start the engine and bring to normal operating temperature (cooling fan ON). Ensure that all accessories are OFF, the front wheels are in the straight ahead position and the transmission is in Neutral (auto. trans. in N or P). Check the engine idle speed and adjust if necessary .
b. Turn the ignition OFF and connect the ignition timing adjustment connector (Tune & Code Access Diagrams) to earth. Connect a timing light, start the engine and allow to idle. Check for a basic ignition timing of 5º ± 2º BTDC. If the timing requires adjustment, loosen the distributor mounting nut and rotate the sensor anti-clockwise to retard the timing and clockwise to advance the timing. Tighten the sensor mounting nut when timing is correct.
c. Stop the engine, disconnect the wire connecting the ignition timing adjustment connector to earth, start the engine and allow to idle. Check that the actual ignition timing is 10º BTDC.

Idle Mixture
Idle mixture is controlled by the ECU. There is no applicable adjustment procedure.

Fuel Pump Pressure
a. Release fuel line pressure . Remove the high pressure fuel hose at the delivery side and attach a fuel pressure gauge to the fuel hose (Tune & Code Access Diagrams).
b. Disconnect the vacuum hose from the pressure regulator and plug the hose end. Start the engine, allow to idle and check for leaks. The pressure gauge should indicate a pressure of 330-350 kPa.
c. Stop the engine and reconnect the vacuum hose to the pressure regulator. Start the engine, allow to idle and check for leaks. The pressure should now be approximately 270 kPa.
d. If the readings are below specification, check the fuel lines, filter and pressure regulator for damage or restrictions. Repair or replace as required. If satisfactory, replace the fuel pump.
e. If the readings are above specification, check the fuel lines and pressure regulator for damage or restrictions. Repair or replace as required. If the pressure reading is the same whether the vacuum hose is connected or disconnected, check the pressure regulator, the vacuum hose and nipple for damage or restrictions. Repair or replace as required.
f. Stop the engine and ensure that the pressure reading remains constant for at least two minutes. If the reading drops slowly, check the injectors for leakage and replace if necessary. If the pressure reading drops immediately, check the fuel pump valve and replace the fuel pump if necessary.
g. Remove the pressure gauge and install a new O-ring to the high-pressure hose. Connect the hose, start the engine and ensure there are no fuel leaks.

TROUBLE CODES ACCESS

Description
When the ECU detects a fault, the check engine light on the instrument cluster illuminates (Tune & Code Access Diagrams) and a fault code is recorded in the ECU memory. Codes recorded are retained in memory until power supply to the ECU is interrupted. The following text includes an ECU fault code table and details procedures for testing the check engine light, reading ECU codes (using an analogue voltmeter) and erasing ECU codes.

Check Engine Light
a. Turn the ignition ON. Ensure that the check engine light illuminates, and is then extinguished after five seconds.
b. If the light fails to illuminate, check for a blown globe and/or fuse. If satisfactory, check the wiring harness for continuity and repair or replace as required.

Reading Codes
a. Place the transmission in Neutral and turn all accessories OFF.
b. Connect an analogue voltmeter (12 V scale) or LED test light between the MPI diagnosis and earth terminals of the diagnosis connector (Tune & Code Access Diagrams). Turn the ignition ON and observe the voltmeter or test light. Any codes present will be displayed as voltmeter needle fluctuations or light pulses. Code 12, for example, is displayed as one medium length fluctuation/pulse (tens), a slightly longer pause (no fluctuation/pulse) and two short fluctuations/pulses (units).
c. If more than one fault code has been recorded, the codes are displayed in numerical sequence and will continue to be displayed until the power supply to the ECU is disconnected.

Erasing Codes
a. Turn the ignition OFF and disconnect the cable from the battery negative terminal for at least 10 seconds.
b. Connect the cable to the battery negative terminal and ensure that no fault codes are displayed (voltmeter displays continuous short needle fluctuations).

FAULT CODE TABLE

Codes

Description

11

Oxygen Sensor

12

Air Flow Sensor (AFS)

13

Intake Air Temperature Sensor

14

Throttle Position Sensor (TPS)

15

Motor Position Sensor (MPS)

21

Coolant Temperature Sensor

22

Crank Angle Sensor

24

Top Dead Centre (TDC) Sensor

25

Barometric Pressure Sensor

41 Fuel Injector Circuit
42 Fuel Pump Circuit

Continuous high voltage reading - ECU faulty

Continuous short fluctuations - System Normal

ECU PINDATA

Terminal Component Condition

Voltage

4
4
4
Oxygen Sensor
Oxygen Sensor
Oxygen Sensor
At idle
At 2000 rpm
Decelerating from 4000 rpm

0.4 V or less
0.6 - 1 V
0.2 V or less

5
5
Power Steering Pressure Switch
Power Steering Pressure Switch
Operating at idle
Not operating at idle

0 V
11 - 13 V

6
6
Idle Position Switch
Idle Position Switch
Throttle valve in idle position
Throttle valve slightly open

0 - 1 V
More than 4 V

7
7
Air-Conditioning Dual Pressure Switch
Air-Conditioning Dual Pressure Switch
Switch ON
Switch OFF

11 - 13 V
0 V

8 Intake Air Temperature Sensor Ignition ON

Approx. 5 V

10 Air Flow Sensor Ignition ON

Approx. 5 V

13 & 23 Barometric Pressure Sensor,Throttle Position Sensor, Motor Position Sensor Reference Voltage Ignition ON

Approx. 5 V

14 & 24 Air Flow Sensor, Intake Air Temperature Sensor, Barometric Pressure Sensor, Coolant Temperature Sensor, Throttle Position Sensor, Motor Position Sensor Reference Voltage Ignition ON

Approx. 5 V

16 Barometric Pressure Sensor At 760 mm Hg (Sea level)

Approx. 4 V

17
17
17
Motor Position Sensor
Motor Position Sensor
Motor Position Sensor
At Idle In Neutral (Accessories OFF)
At Idle Air-conditioning ON (If fitted)
At Idle In Drive (Auto. trans. models)

0.5 - 1.3 V
0.9 - 1.9 V
0.9 - 1.9 V

18 Vehicle Speed Sensor Ignition ON, Four times per speedo cable revolution

0 - 5 V

19
19
Throttle Position Sensor (TPS) Voltage
Throttle Position Sensor (TPS) Voltage
At closed throttle
At fully open throttle

0.45 - 0.6 V
4.5 - 5.5 V

20 Coolant Temperature Sensor Harness disconnected from sensor

Approx. 5 V

21 Crank Angle Sensor Ignition ON

Approx. 5 V

22 Top Dead Centre Sensor Ignition ON

Approx. 5 V

23 Refer Terminal 13  

 

24 Refer Terminal 14  

 

51 Injector No. 1 Ignition ON

11 - 13 V

52 Injector No. 2 Ignition ON

11 - 13 V

56 MPI Control Relay At idle

11 - 13 V

60 Injector No. 3 Ignition ON

11 - 13 V

61 Injector No. 4 Ignition ON

11 - 13 V

62 Purge Control Solenoid (CB Models only) Ignition ON

11 - 13 V

64
64
Check Engine Light
Check Engine Light
For 5 seconds after Ignition ON
Other conditions

0 V
11 - 13 V

65 Air-Conditioning Compressor Relay Ignition ON

11 - 13 V

101 Earth Constant

0 V

102 MPI Control Relay Ignition ON

11 - 13 V

103 Battery Power Constant

11 - 13 V

104
104
Ignition in START Position
Inhibitor Switch
Ignition in START Position ECU earth (Manual Transmission)
Ignition in START Position Inhibitor Switch in N or P (Automatic Transmission)

0 V
11 - 13 V

106 Earth Constant

0 V

107 MPI Control Relay Ignition ON

11 - 13 V

108
108
Ignition Switch (Manual Transmission)
Inhibitor Switch
Ignition in START Position
Ignition in START Position Inhibitor Switch in N or P (Automatic Transmission)

11 - 13 V
11 - 13 V

109 MPI Control Relay Ignition ON

11 - 13 V

Diagrams:

+ Component Locations
+ Under Bonnet Locations
+ ECU Pin Layout
+ Emission Controls Layout Diagram
+ Tune & Code Access Diagrams
+ Engine Management Wiring Diagram (CA)
+ Engine Management Wiring Diagram (CB)