DESCRIPTION
The Electronic Control Injection system (ECI) is a computerized emission and fuel control system. The ECI system controls engine operation and lowers exhaust emissions while maintaining good fuel economy and driveability. The Electronic Control Unit (ECU) is the "brain" of the ECI system. The ECU controls many engine related systems to constantly adjust engine operation.
The ECI system is primarily an emission control system, designed to maintain an ideal air/fuel ratio under all operating conditions. When an ideal ratio is maintained, the catalytic converters can control carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) emissions.
OPERATION
The ECI system consists of the following subsystems: Fuel Control, Data Sensors, Electronic Control Unit (ECU), Idle Speed Control (ISC), Emission Control, Fuel Cut-Off, catalytic converters and other related components.
FUEL CONTROL OPERATION
Fuel control system consists of an electric fuel pump, control relay, fuel filter, fuel injectors, fuel pressure regulator, fuel lines and airflow sensor. Fuel is supplied to engine through 2 electronically pulsed (timed) injector valves located in fuel injection mixer above intake manifold (Galant has only 1 injector). The ECU controls amount of fuel metered through injectors based upon engine demand information, through data sensor signals.
DATA SENSORS OPERATION
Each sensor furnishes electrical impulses to ECU. The ECU computes fuel delivery and spark timing necessary to maintain desired air/fuel mixture, thus controlling amount of fuel delivered to engine. Data sensors are interrelated to each other. Operation of each sensor is as follows
AIRFLOW SENSOR
This sensor is mounted in air cleaner assembly. The sensor measures airflow rate through the air cleaner and sends a proportionate electrical signal to ECU. The ECU uses airflow sensor information for controlling fuel delivery and the secondary air management. On Conquest and Starion intercooled models, an atmospheric pressure pick-up nipple (leading to atmospheric pressure switching solenoid valve) has been added to air cleaner and locations of oil separator and breather nipple have been changed.
INTAKE AIR TEMPERATURE SENSOR
This sensor is mounted to modulator located the in air cleaner, as a component part of airflow sensor. The sensor measures temperature of incoming air, supplying air density information to the ECU. The ECU uses air temperature sensor information for controlling fuel delivery. On Conquest and Starion intercooled models, an intake air temperature sensor "B" has been installed to air intake pipe to obtain optimum air-fuel mixture according to intake air temperatures when engine is operating under high load.
Chrysler Corp. Imports Colt & Conquest/Mitsubishi Cordia, Mirage, Starion & Tredia ECI System. Scheme 11
PRESSURE SENSOR
This sensor is mounted on firewall. An electrically controlled solenoid valve is connected to sensor. The solenoid valve has 2 hoses connected to it. One hose connects to air cleaner duct and other hose connects below throttle valve.
The solenoid valve is activated by ECU whenever ignition switch is turned to "ON" or "START" positions, for a specific period of time. When activated, the solenoid measures ambient barometric pressure from above throttle valve. Ambient barometric pressure changes due to weather and/or altitude. This information is sent to ECU for controlling fuel delivery time.
After a predetermined period of time, solenoid valve is deactivated by ECU. When deactivated, the solenoid measures intake manifold pressure below throttle valve. The ECU compares barometric pressure and intake manifold pressure and an absolute value is used to determine fuel delivery and ignition timing.
The pressure sensor and solenoid valve are also used for altitude compensation. These components inform ECU of altitude. The ECU calculates air/fuel ratio necessary for engine operation in high altitude areas.
Pressure Sensor Note solenoid valve and pressure sensor locations. Scheme 12
COOLANT TEMPERATURE SENSOR (CTS)
The coolant temperature sensor is installed in intake manifold. This sensor is a thermistor which converts the temperature of engine coolant to an electrical signal for use by ECU. The ECU uses coolant temperature information for controlling fuel delivery time, EGR and air injection system.
ENGINE SPEED SENSOR
Engine speed signal is received from ignition coil. Electrical signals from ignition coil are sent to ECU where time between signals is used to calculate engine speed. This information is used by ECU for controlling fuel delivery time, EGR and air injection system.
OXYGEN SENSOR
This sensor is mounted in exhaust system between turbocharger and front catalytic converter. Output voltage of oxygen sensor varies with oxygen content in exhaust gas stream.
When oxygen sensor signal is being interpreted by ECU, information is used to control fuel delivery time. This is called closed loop mode of operation. When oxygen sensor signals are not being interpreted by ECU, this is open loop mode of operation.
THROTTLE POSITION SENSOR
This sensor is mounted on fuel injection mixer. The sensor, a rotary potentiometer, signals ECU of changes in throttle valve position. This information is used for controlling fuel delivery time.
IDLE POSITION SWITCH
This switch is mounted on fuel injection mixer. When throttle valve is closed (idle position), the switch is activated. When throttle valve is at any other position, the switch is deactivated. This information is used by the ECU for controlling fuel delivery time (during deceleration) and air injection system. This switch is also used as an idle speed adjusting device.
Idle Speed Control (ISC) System. Scheme 13
ELECTRONIC CONTROL UNIT (ECU)
The ECU consists of a printed circuit board enclosed within a metal box. The ECU receives various signals from data sensors and switches. These signals are processed by the ECU for controlling fuel delivery.
The amount of fuel delivered is determined only by the time that injectors are open, because the fuel pressure regulator maintains a constant pressure drop across injectors. The frequency and duration of injection (fuel delivery time) is controlled by ECU.
The ECU monitors various engine and vehicle operations and computes the fuel delivery time. Fuel delivery time is modified for such operating conditions as engine cranking, cold starting, altitude, acceleration and deceleration.
When ignition switch is turned to "START" position, ECU calculates fuel delivery based primarily upon coolant temperature and throttle position. ECU sends an electrical signal to injectors to provide fuel for prescribed period of time. After ignition is released from "START" position and engine speed is above a specified RPM, ECU changes enrichment signal.
Immediately after engine starts, the ECU issues electrical signals to injectors to provide stable combustion. During engine warm-up, the ECU monitors all data sensor information and provides a richer mixture until coolant temperature reaches a preset value.
When coolant temperature exceeds preset value, ECU processes other data sensor information and issues appropriate electrical signals to injectors. This period of time is referred to as open loop mode of operation. The ECU controls fuel delivery based upon open loop programmed information until the oxygen sensor is warm enough to send modifying signals to ECU.
When the oxygen sensor is warm enough, the ECU accepts oxygen sensor information and uses it for controlling fuel delivery. When the ECU is accepting oxygen sensor information, this is referred to as closed loop mode of operation.
During closed loop operation, the ECU stores the mean values of feedback signals used to maintain optimum air fuel ratio. During open loop operation, the ECU uses these mean values to modify pre-programmed information. By doing this, the ECU can more closely control exhaust emissions even when engine is in open loop mode of operation.
Electronic Control Unit Terminal ID. Scheme 14
Air Injection System (Secondary Air Supply)
The ECU controls the air injection system. The air injection system consists of a secondary air filter, reed valve, secondary air control valve and secondary air solenoid valve. (Scheme 19) This system reduces exhaust emissions by promoting oxidation of exhaust gases.
The ECU monitors engine speed, intake airflow, coolant temperature and idle position. When all required conditions are met, the ECU activates the solenoid valve to supply secondary air to exhaust manifold during engine warm-up, hot-start and deceleration modes of operation.
When the ECU activates the solenoid valve, intake manifold vacuum opens the secondary air control valve. The control valve allows additional air to enter the exhaust manifold. The reed valve, actuated by vacuum pulsations in exhaust manifold, controls the amount of additional air entering the exhaust manifold.
Air Injection (Secondary Air Supply) System ECU monitors engine and controls air injection. Scheme 15
EGR System
An EGR system is used to reduce oxides of nitrogen (NOx) emissions in vehicle exhaust gases. Exhaust gas is partially recirculated from an exhaust port in cylinder head into an intake manifold port below fuel injection mixer. The EGR system is controlled by the ECU and consists of an EGR control solenoid valve and EGR control valve. (Scheme 20)
The ECU monitors engine speed and coolant temperature. When conditions are met, the ECU de-energizes the EGR solenoid valve. When solenoid is de-energized, EGR control valve is opened (aided by throttle ported vacuum) and EGR flow occurs.
When EGR solenoid is energized by ECU, control valve closes due to combined forces of throttle ported pressure and turbocharged pressure.
The EGR flow is suspended during engine idle and wide open throttle operation. The ECU does not allow EGR flow if engine conditions do not meet the predetermined criteria.
EGR System, ECU monitors engine and controls EGR flow. Scheme 16
FUEL CUT-OFF
Two different fuel cut-off systems are used to change fuel delivery rate to engine
Deceleration Fuel Cut-off
During vehicle operation, idle position switch not at idle position, fuel delivery is determined by ECU responding to throttle valve closing speeds.
To decrease HC emissions during vehicle deceleration, fuel delivery time is decreased by ECU changing injection interval. When engine is operated under predetermined conditions, injection interval is changed from once every 3 pulses of airflow sensor to once every 6 pulses of airflow sensor.
Over Boost Fuel Cut-off
This fuel cut-off system protects the engine during turbocharger operation. When the pressure sensor detects higher manifold pressure than the predetermined value stored in ECU memory, the ECU changes fuel delivery rate.
TESTING & DIAGNOSIS
| CAUTION | Be sure ignition switch is in "OFF" position when disconnecting connectors from control unit. While testing, be careful not to bend any pins and do not touch more than 1 pin at a time with meter lead as meter or ECU could be damaged. |
PRETESTING INSPECTION
If ECI system components fail, interruption of fuel supply or failure to supply proper amount of fuel for engine operation will result. The following conditions will result: engine is hard to start or does not start at all, unstable idle and/or poor driveability. Before testing ECI system, perform basic engine checks first (ignition system, incorrect engine adjustments, etc.).
SELF-DIAGNOSIS
The Self-Diagnosis system monitors by the computer (ECU) the input signal from each sensor. If any abnormality occurs in input signal, the abnormal item is memorized by the computer (ECU). The diagnosis items are 9 (Colt, Cordia, Galant, Tredia) items including normal operating conditions and can be confirmed by using a voltmeter (Colt, Conquest, Galant) or ECI Checker, Diagnostic Harness Connector and Connector "B" (Cordia, Mirage, Starion, Tredia). (Scheme 21)and (Scheme 22).
Chrysler Corp. Diagnosis Connector. Scheme 17
Mitsubishi Diagnostic Components. Scheme 18
The abnormality-diagnosis memory is kept by direct power supply from the battery. Memory of diagnosis result is not erased by turning off ignition switch but will be erased if back-up power supply is turned off by disconnection of battery cable or ECU unit.
Note. Memory is not erased if power supply is turned on within 10 seconds after turning off power supply of ECU. Diagnosis Items
The abnormality-diagnosis items are listed in the following table. If 2 or more items are found abnormal, they are indicated in order of increasing code number.
Indication is made by deflection of voltmeter pointer or ECI check components. A constant 12V is indicated when system is normal. When abnormal, indication alternates between 0V and 12V every 0.4 seconds. Engine speed at 12V is indicated. After indication of 0V for 2 seconds, the higher code is indicated. (Scheme 23)
| Code Number | Diagnosis Item |
|---|---|
| 1 | Oxygen Sensor & Computer |
| 2 | Ignition Pulse |
| 3 | Airflow Sensor |
| 4 | Pressure Sensor |
| 5 | Throttle Position Sensor |
| 6 | ISC Motor Position Sensor |
| 7 | Coolant Temperature Sensor |
| 8 | Vehicle Speed Sensor |
DIAGNOSTIC CODE CHART
Self-Test Indication Chart, Codes 2 & 5 Shown As Abnormal. Scheme 19
SELF-DIAGNOSIS TEST
- Turn ignition switch to "OFF" position. On Colt models connect voltmeter between Self-Diagnosis Output and Ground of diagnosis connector, located in engine compartment.
- On Mirage models use Diagnosis Harness Connector and Diagnosis Adapter to connect ECI Checker to diagnosis connector located in engine compartment. On ECI Checker, set check switch to "6" and select switch to "B".
- On all models, turn ignition switch to "ON" position and indication of ECU memory will start. If there is any abnormality in the memory, perform the necessary component repairs. Turn ignition off and disconnect battery negative ground cable for 15 seconds or more then reconnect cable to ensure abnormal code has been erased.
Note. Before battery terminals are disconnected, make sure that ignition is off. If terminals are disconnected while engine is running or ignition is on, computer or semiconductors could be damaged.
ECI INSPECTION TEST
Note. Perform ECI Inspection test only after completing all steps of preceding Self-Diagnosis test. Chrysler Corp. Imports
With voltmeter, use following charts to identify the pin connectors. (Scheme 25) Check voltage of each terminal as specified in charts. Make sure ignition switch, vehicle operation and conditions are observed as called out in procedure.
Colt Pin Connectors. Scheme 20
Scheme 21
- Turn Ignition switch to "OFF" position and remove cover from ECU. Remove body side harness connectors "A" (17 poles) and "B" (13 poles) from ECU. On ECI checker, set check switch to "OFF" position and select switch to "A". Connect ECI checker Connector by using ECU Harness Connector to ECU and body harness connectors. (Scheme 26) Place ECI Checker on front passenger's seat.
- Check output monitor operating condition (on or off) by switching ignition switch from "OFF" to "ON". Monitor operating condition should be as follows: Airflow Sensor - ON, Injector Pulse - OFF, Oxygen Sensor - OFF. Perform checks according to following charts. (Scheme 21): Mitsubishi ECU Harness Connector
- If checker shows any departure from specifications, check corresponding sensor and related electrical wiring. After repair or replacement of defects, recheck with ECI checker to confirm that repaired or replaced part is performing well.
- Airflow sensor and injector pulse may be inspected by output monitors as well. Set select switch to "B". Normal operation is as follows: Airflow Sensor and Injector are always flashing with check switch at "1" through "12". Oxygen Sensor is flashing at closed loop zone. The flashes will be so short that light will appear to be continuously on.
- Set check switch of ECI checker to "OFF" position. Set ignition switch to "OFF" position. Disconnect connectors of ECI checker from ECU and body side harness connectors. Connect body side harness connector to ECU. Install ECU cover.
Diagnostic Check No. 1 (O2 Sensor)
O2 sensor does not change for 20 seconds or more. Check wire harness and connector, oxygen sensor and ECU. When engine stalls, turn ignition switch from "OFF" position to "ON" position. If abnormal code is indicated, computer is normal. If no indication is made, computer is not in normal condition.
Diagnostic Check No. 2 (Ignition Pulse Sensor)
While cranking the engine, input of ignition signal is not applied to computer for 3 seconds or more. Check wire harness and connector, igniter and ECU.
Diagnostic Check No. 3 (Airflow Sensor)
Airflow sensor output is 10 cycles per second or less while engine is idling, or it is 100 cycles per second or more when engine stalls. Check wiring harness and connector, airflow sensor and ECU.
Diagnostic Check No. 4 (Pressure Sensor)
Pressure sensor output is 4.5 volts or more at 57 in. Hg or more, or it is .2 volts or less at 2.4 in. Hg. Check wiring harness and connector, pressure sensor and ECU.
Diagnostic Check No. 5 (Throttle Position Sensor)
Throttle position sensor is .2 volts or less, or it is 4 volts or more while engine is idling (idle switch on). Check wire harness and connector, ISC servo and ECU.
Diagnostic Check No. 6 (ISC Motor Position Sensor)
Throttle sensor output is .40 volts with L switch off. Check wiring harness and connector, ISC servo and ECU.
Diagnostic Check No. 7 (Coolant Temperature Sensor)
Water temperature sensor output is 4.5 volts or more, or it is .1 volt or less. Check wire harness and connector, water temperature sensor and ECU.
Diagnostic Check No. 8 (Vehicle Speed Sensor)
Airflow sensor output is 500 cycles per second or more, and vehicle speed is 1.6 MPH or less. Check wire harness and connector, vehicle speed sensor and ECU.
AIRFLOW SENSOR TEST
- To remove, disconnect airflow sensor connector. Unsnap finger clip and remove air cleaner cover. Remove filler from air cleaner body. Remove airflow sensor.
- To inspect, check air cleaner element, case and cover for damage and contamination. Replace if necessary. Perform «ECI INSPECTION TEST»(/mitsubishi/mirage/ii-1983-1988/remont/testing-diagnostics/#fuel-injection-system-eci__eci-inspection-test) . Check intake air temperature sensor by measuring resistance. AIRFLOW SENSOR (AFS) RESISTANCE Temperature °F (°C) Resistance (Ohms) 68 (20) 2500
- To install, reverse removal procedure making sure airflow sensor connector is securely connected.
Measuring Air Temperature Sensor Resistance Make sure leads are properly connected. Scheme 22
COOLANT TEMPERATURE SENSOR TEST
- Remove coolant temperature sensor from intake manifold and dip end of sensor into water. Do not allow sensor to touch container. Terminal connector portion of sensor should be .12" (3 mm) above water.
- Gradually heat water and read resistance values at terminal connectors. Resistance should be as shown in «COOLANT TEMPERATURE SENSOR RESISTANCE»(/mitsubishi/mirage/ii-1983-1988/remont/testing-diagnostics/#fuel-injection-system-eci) chart. If not, replace sensor.
| Temperature °F (°C) | Resistance (Ohms) |
|---|---|
| 68 (20) | 2450 |
| 176 (80) | 296 |
COOLANT TEMPERATURE SENSOR RESISTANCE
RESISTOR TEST
- Disconnect electrical connector from resistor. Measure resistance across terminals "1" and "2", then "1" and "3". If resistance is about 6 ohms, resistor is good.
- If resistance measures 0 or abnormally large, resistor has short or open circuit. Replace resistor.
EFI Control Relay Terminal Positions. Scheme 23
CONTROL RELAY TEST
- Control relay is mounted on top of ECU. Disconnect electrical harness and test continuity between terminals "1" and "7", then "3" and "7". If there is no continuity, relay is good. If continuity is measured, replace control relay.
- Apply 12 volts across terminals "8" (positive) and "4" (negative) while testing continuity between terminals "3" and "7". If continuity is measured, relay is good. If not, replace relay.
- Apply 12 volts across terminals "6" (positive) and "4" (negative) while testing continuity between terminals "1" and "7". If there is continuity, relay is good. If not, replace relay.
- Apply 12 volts across terminals "5" (positive) and "2" (negative) while testing continuity between terminals "1" and "7". If there is continuity, relay is good. If not, replace relay.
INJECTOR COIL TEST
Turn ignition switch to "OFF" position. Disconnect connectors from injectors and check continuity. If resistance measures 0 or is abnormally large there is a short or open circuit in coil. Replace injector.
IDLE SWITCH TEST
- Turn ignition switch to "OFF" position. Disconnect ISC servo connector. Check for continuity between pole "2" and injection mixer body.
- If continuity exists when throttle valve is placed in idle position and if no continuity exists when throttle valve is open (so that lever leaves idle switch), switch is good.
- If continuity exists when throttle valve is in both positions, contacts are bound together. If no continuity exists when throttle valve is in both positions, grounding is defective. Replace ISC servo assembly.
ISC SERVO TEST
- Connect voltmeter between terminal "3" and injection mixer body. Do not disconnect ISC servo connector. Turn ignition switch to "OFF" position then to "ON" position. While keeping ignition on for at least 15 seconds, check voltmeter reading.
- If voltmeter needle reads 11V-13V with ignition switch on after momentary indication of 1V, needle indicates 6V-13V, ISC servo and position switch are operating normally. Turn ignition switch to "OFF" to remove voltmeter.
ISC SERVO MOTOR TEST
- Turn ignition switch to "OFF" position. Disconnect ISC servo connector. Check motor coil continuity between terminals "1" and "4". Resistance should read between 7 and 10 ohms. If resistance is 0 ohms or abnormally large, open or short circuit exists in motor coil. Replace ISC servo assembly.
- Make sure there is no continuity between terminal "1" or "4" and injection mixer body. If continuity exists, there is a short circuit in coil. Replace ISC servo assembly.
THROTTLE POSITION SENSOR TEST
- Turn ignition switch to "OFF" position. Disconnect sensor connector. Check resistance across poles "1" and "3". Total resistance should read 4000-6000 ohms.
- Connect a circuit tester across poles "1" and "2" or across poles "2" and "3". Check to ensure that when throttle valve is slowly operated from idle to fully opened position, resistance changes smoothly.
| Temperature °F (°C) | Resistance (Ohms) |
|---|---|
| 68 (20) | 2450 |
INTAKE AIR TEMP SENS "B" RESISTANCE
Scheme 24
- Run engine at fast idle until coolant temperature is 185-205°F (85-90°C). Turn off engine. Disconnect accelerator cable from throttle lever of injection mixer. Loosen the 2 screws installing the throttle position sensor.
- Turn throttle position sensor fully clockwise. Tighten screws. Turn ignition switch to the "ON" position for more than 15 seconds, then turn ignition switch to "OFF" position. This will set ISC servo to specified position. Disconnect ISC servo harness connector. Start engine. Check engine speed and adjust to specification with screw. (Scheme 29) ENGINE IDLE SPEEDS Application ISC RPM Colt & Mirage 600 (Scheme 24): Chrysler Corp. Imports Colt ECI System Check Chart (1 of 2)
- Stop engine. To read output voltage of TPS, insert test probe from rubber cap side of TPS connector and bring it into contact with connector pins. Insert test probes along "GW" lead (TPS output) and "B" lead (ground) of body side harness. (Scheme 30)
- Turn ignition switch to "ON" position without starting engine. Read TPS output voltage. If measurement of output voltage does not agree with.45-.51V, loosen TPS mounting screws and turn sensor clockwise or counterclockwise until output voltage is 45-51V.
- Immediately open throttle valve, return it to original position and check for proper output voltage readjusting if necessary. Remove adapter, voltmeter and test probes and reconnect ISC servo harness connector.
- Make sure idle speed is normal. Stop engine and turn ignition switch from "OFF" position to "ON" position and after 15 seconds back to "OFF" position. Connect accelerator cable to throttle lever of injection mixer and adjust accelerator cable.
