Eci Cec System Mitsubishi Starion I

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 foundation of the ECI system. The ECU controls many of the related systems to constantly adjust engine operation.

OPERATION

The ECI system is primarily an emission control system, designed to maintain ideal air/fuel ratio under all operating conditions. When an ideal ratio is maintained, the catalytic converter can control carbon monoxide (CO), hydrocarbon (HC) and oxides of nitrogen (NOx) emissions.

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

Fuel control system consists of an electric fuel pump, control relay, fuel filter, injectors, pressure regulator and airflow sensor. Engine fuel is supplied through 2 electronically pulsed (timed) injector valves located in fuel injection mixer above intake manifold. The ECU controls amount of fuel metered through injectors based upon engine demand information supplied through data sensor signals.

DATA SENSORS

Each sensor furnishes electrical impulses to ECU. From this input, the ECU computes fuel delivery and spark timing necessary to maintain desired air/fuel mixture. (Scheme 7) This controls amount of fuel delivered to engine. Data sensors are interrelated to each other. Their operation is as follows

Airflow Sensor

Airflow sensor is mounted inside the air cleaner assembly. The sensor measures airflow rate through the air cleaner and sends a proportionate electrical signal to ECU. On intercooled models, an atmospheric pressure pick-up nipple (leading to atmospheric pressure switching solenoid valve) has been added to air cleaner. The location of oil separator and breather nipple have been changed.

Coolant Temperature Sensor (CTS)

The coolant temperature 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

The 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.

Idle Position Switch

The Idle Position Switch (IPS) is mounted on fuel injection mixer. When throttle valve is closed, 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. (Scheme 7)

Intake Air Temperature Sensor

The sensor measures temperature of incoming air and supplies air density information to the ECU. The ECU uses air temperature sensor information for controlling fuel delivery. On 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.

Mitsubishi Motors Starion ECI System. Scheme 4

Mitsubishi Motors Starion Intercooled Turbo ECI System. Scheme 5

Oxygen Sensor

The oxygen sensor is located in the exhaust system between turbocharger and 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.

Pressure Sensor

The solenoid valve is temporarily activated by ECU whenever ignition switch is turned to "ON" or "START" positions. 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. (Scheme 6)

After a predetermined period of time, solenoid valve is deactivated by ECU and solenoid measures intake manifold pressure below throttle valve. The ECU compares barometric pressure to 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 6

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 Speed Control (ISC) System. Scheme 7

ECU Data Processing. Scheme 8

ELECTRONIC CONTROL UNIT (ECU)

The ECU is a printed circuit board enclosed in a metal housing. The ECU receives various signals from data sensors and switches. These signals are processed by the ECU for controlling fuel delivery. (Scheme 8)

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 to compute 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 specific period of time. After ignition is released from "START" position and engine speed is above a specified RPM, ECU changes the 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 for controlling fuel delivery. 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.

On Starion intercooled models, 2 additional ECU control functions have been added; a high altitude advance correcting function and the input circuit of intake air temperature sensor "B" signal.

Electronic Control Unit Terminal Identification (Intercooled Models). Scheme 9

Air Injection System (Secondary Air Supply)

The air injection system consists of a secondary air filter, reed valve, secondary air control valve and secondary air solenoid valve. 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 System ECU monitors engine and controls air injection. Scheme 10

EGR System

An EGR system is used to reduce oxides of nitrogen (NOx) emissions from vehicle exhaust gases. Exhaust gas is partially recirculated from an exhaust port in cylinder head into the 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 11)

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 ported vacuum) and EGR flow occurs.

When EGR solenoid is energized by ECU, control valve closes due to combined forces of 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 standard.

EGR System ECU monitors engine and controls EGR flow. Scheme 11

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, with throttle 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 value stored in the ECU memory, the ECU changes the fuel delivery rate.

TESTING

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 (ignition system, incorrect engine adjustments, etc.).

SELF-DIAGNOSIS

The Self-Diagnosis system, an integral part of the computer (ECU), monitors all input signals from each sensor. If an abnormal input signal occurs, that item is memorized by the computer (ECU). There are 8 diagnostic codes including normal operating condition. They can be confirmed by using an ECI checker with adapters (Starion). (Scheme 11)and (Scheme 12).

Chrysler Motors Diagnosis Connector. Scheme 12

The ECU memory is kept by direct power supply from the battery. Memory is not erased by turning off ignition switch but will be erased if back-up power supply is eliminated by disconnecting battery cable or ECU unit.

Note. Memory will not be erased if power supply is returned 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 systems are non-functional, they are indicated in order of increasing code number.

Indication is made by deflection of voltmeter pointer or ECI check components. A constant 12 volts indicates system is normal. If system is abnormal, voltmeter will alternate between 0 and 12 volts every 0.4 seconds. After indication of 0 volts for 2 seconds, the higher code is indicated. (Scheme 11)

DIAGNOSTIC CODE CHART

Self-Test Indication Chart Chart illustrates code 2 and 5 as being abnormal. Scheme 13

SELF-DIAGNOSIS TEST

1. Turn ignition switch to "OFF" position. On Starion models, connect voltmeter between Self-Diagnosis Output and Ground of diagnosis connector, located in engine compartment. (Scheme 10)
2. For 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 to erase ECU memory.

Note. Before disconnecting battery terminals, make sure that ignition is off. Disconnecting terminals with ignition on or engine running could damage computer system.

ECI INSPECTION TEST

Note. Perform ECI Inspection test only after completing all steps of preceding Self-Diagnosis test.

Chrysler Motors

With voltmeter, measure the voltage at the appropriate pin connectors. (Scheme 9) Check voltage standards of each terminal as specified in ECI SYSTEM CHECK CHARTS at the end of this article. Make sure ignition switch, vehicle operation and conditions are observed as called out in procedure.

Scheme 14

1. 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 14) Place ECI checker on front passenger seat.
2. Check output monitor operating condition (on or off) by switching ignition switch from "OFF" to "ON" position. Monitor operating condition should be as follows: Airflow Sensor - ON, Injector Pulse - OFF, O2 Sensor - OFF. Perform checks according to the «ECI SYSTEM CHECK CHARTS»(/mitsubishi/starion/i-1982-1990/remont/testing-diagnostics/#eci-cec-system) at the end of this article. (Scheme 14): Mitsubishi ECU Harness Connector
3. If checker reading varies from specifications, check corresponding sensor and related electrical wiring. After component repair or replacement, recheck to confirm system performance.
4. 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.
5. Set check switch of ECI checker to "OFF" position. Set ignition switch to "OFF" position. Carefully separate connectors of ECI checker from ECU and body side harness connectors. Connect body side harness connector to ECU. Install ECU cover.

Diagnostic Check Number 1 (O2 Sensor)

If O2 sensor change exceeds 20 seconds while in feedback range, turn ignition switch from "OFF" position to "ON" position. If trouble code is indicated, computer is normal. If trouble code is not indicated, computer operation is not normal. Check wire harness and connector, O2 sensor and ECU.

Diagnostic Check Number 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 Number 3 (Airflow Sensor)

Airflow sensor maximum output is 10 cycles per second while engine is idling. If engine stalls, output will rise to 100 cycles per second. Check wiring harness and connector, airflow sensor and ECU.

Diagnostic Check Number 4 (Pressure Sensor)

Pressure sensor should be under .2 volts or over 4 volts while engine is idling (idle switch on). Check wiring harness and connector, pressure sensor and ECU.

Diagnostic Check Number 5 (Throttle Position Sensor)

Throttle position sensor should be under .2 volts or over 4 volts while engine is idling (idle switch on). Check wire harness and connector, ISC servo and ECU.

Diagnostic Check Number 6 (ISC Motor Position Sensor)

Throttle sensor output is .4 volts with L switch off. Check wiring harness and connector, ISC servo and ECU.

Diagnostic Check Number 7 (Coolant Temperature Sensor)

Coolant temperature sensor should be under .1 volts or over 4.5 volts. Check wire harness and connector, water temperature sensor and ECU.

Diagnostic Check Number 8 (Vehicle Speed Sensor)

Airflow sensor output is 500 cycles per second or more when vehicle speed is 1.6 MPH or less. Check wire harness and connector, vehicle speed sensor and ECU.

1. Disconnect airflow sensor connector. Unsnap finger clip and remove air cleaner cover. Remove filler from air cleaner body. Remove airflow sensor.
2. To inspect, check air cleaner element, case and cover for damage and contamination. Replace if necessary. Check intake air temperature sensor by measuring resistance. AIRFLOW SENSOR (AFS) RESISTANCE Temperature °F (°C) Resistance (Ohms) 68 (20) 2500
3. Reverse removal procedure to install airflow sensor. Make sure that connector is securely attached.

Measuring Airflow Sensor Resistance Make sure leads are properly connected. Scheme 15

Coolant Temperature Sensor

1. Remove coolant temperature sensor from intake manifold and place end of sensor in water. DO NOT allow sensor to touch container. Terminal connector portion of sensor should be .12" (3 mm) above water.
2. Gradually heat water and read resistance values at terminal connectors. Resistance should be as shown in the «COOLANT TEMPERATURE SENSOR RESISTANCE»(/mitsubishi/starion/i-1982-1990/remont/testing-diagnostics/#eci-cec-system) chart. If not, replace sensor.

COOLANT TEMPERATURE SENSOR RESISTANCE

Resistor

1. Disconnect electrical connector from resistor. Measure resistance across terminal Nos. 1 and 2, then 1 and 3. If resistance is about 6 ohms, resistor is good.
2. If resistance measures zero, or is abnormally large, resistor has short or open circuit. Replace resistor.

EFI Control Relay Terminal Positions. Scheme 16

Control Relay

1. Control relay is mounted on top of ECU. Disconnect electrical harness and test continuity between terminal Nos. 1 and 7, then 3 and 7. If there is no continuity, relay is good. If continuity is measured, replace control relay.
2. Apply 12 volts across terminal Nos. 8 (positive) and 4 (negative) while testing continuity between terminal Nos. 3 and 7. If continuity exists, relay is good. If not, replace relay.
3. Apply 12 volts across terminal Nos. 6 (positive) and 4 (negative) while testing continuity between terminal Nos. 1 and 7. If continuity exists, relay is good. If not, replace relay.
4. Apply 12 volts across terminal Nos. 5 (positive) and 2 (negative) while testing continuity between terminal Nos. 1 and 7. If continuity exist, relay is good. If not, replace relay.

Injector Coil

Turn ignition switch to "OFF" position. Disconnect connectors from injectors and check continuity. Resistance should be 2-3 ohms. If resistance measures zero, or is abnormally large, there is a short or open circuit in the coil. Replace injector.

Idle Switch

1. Turn ignition switch to "OFF" position. Disconnect ISC servo connector. Check for continuity between pole No. 2 and injection mixer body.
2. If continuity exists when throttle valve is placed in idle position and continuity exists when throttle valve is open (so that lever leaves idle switch), switch is good.
3. 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

1. Connect voltmeter between terminal No. 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.
2. If voltmeter reads 11-13 volts with ignition switch on after momentary indication of 1 volt, needle indicates 6-13 volts, ISC servo and position switch are operating normally. Turn ignition switch to "OFF" to remove voltmeter.

ISC Servo Motor

1. Turn ignition switch to "OFF" position. Disconnect ISC servo connector. Check motor coil continuity between terminal Nos. 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.
2. Make sure there is no continuity between terminal Nos. 1 or 4 and injection mixer body. If continuity exists, there is a short circuit in coil. Replace ISC servo assembly.

1. Turn ignition switch to "OFF" position. Disconnect Throttle Position Sensor (TPS) connector. Check resistance across poles Nos. 2 and 3.
2. As the throttle valve is slowly operated from closed to wide open throttle, watch meter. Resistance values should make a smooth transition from 500 ohms at closed throttle to 3000-6500 ohms in fully open position.

Intake Air Temperature Sensor "B" (Intercooled Models)

To inspect, disconnect harness connector of intake air temperature sensor. Check resistance across terminals in connector of sensor. If resistance is abnormally small or large, sensor has a short or open circuit and must be replaced.

INTAKE AIR TEMPERATURE SENSOR "B" RESISTANCE

EGR Control Solenoid Valve (Starion)

1. Start engine and run at idle until normal operating temperature is obtained. Disconnect Green striped hose from fuel injection mixer and connect vacuum pump to hose.
2. Separate electrical connector from solenoid valve and apply 9.8 in. Hg vacuum to Green striped hose. If idle becomes unstable or engine stalls, EGR system is operating properly.
3. Reconnect electrical connector and repeat step 2). Engine idle should not be affected. If idle becomes unstable or engine stalls, solenoid valve is remaining closed. Replace solenoid valve.

Mitsubishi Motors Starion ECI Check Chart (1 of 2). Scheme 17

Mitsubishi Motors Starion ECI Check Chart (2 of 2). Scheme 18

Intercooled Turbo Models ECI Check Chart (1 of 2). Scheme 19

Intercooled Turbo Models ECI Check Chart (2 of 2). Scheme 20

IDLE SPEED CONTROL SYSTEM

1. 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.
2. Turn ignition switch to the "ON" position for more than 15 seconds, then turn ignition off. 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 21) ENGINE IDLE SPEEDS Application ISC RPM Starion 750
3. 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 22)
4. Turn ignition switch to "ON" position without starting engine. Read TPS output voltage. Output voltage should be.45-.51 volts. If not, loosen TPS mounting screws and turn sensor until correct output voltage is obtained.
5. 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.
6. 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.

ISC Servo Idle Adjusting Screw. Scheme 21

Checking Throttle Position Sensor Output Voltage. Scheme 22

Starion ECI System Wiring Diagram (Intercooled Models). Scheme 23

See also:
• ECI SYSTEM CHECK CHARTS