SFI SYSTEM DETAILS


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components of the engine control system are as follows:

      Component Outline Quantity Function
      ECM 32-bit CPU 1 The ECM optimally controls the SFI, ESA and ISC to suit the operating conditions of the engine in accordance with the signals provided by the sensors.
      Intake Mass Air Flow Meter Sub-assembly Hot-wire Type 1 This sensor has a built-in hot-wire to directly detect the intake air mass.
      Intake Air Temperature Sensor Thermistor Type 1 This sensor detects the intake air temperature by means of an internal thermistor.
      Engine Coolant Temperature Sensor Thermistor Type 1 This sensor detects the engine coolant temperature by means of an internal thermistor.
      Crankshaft Position Sensor [Rotor Teeth] Pick-up Coil Type (36-2) 1 This sensor detects the engine speed and performs cylinder identification.
      Camshaft Position Sensor [Rotor Teeth] Pick-up Coil Type (3) 1 This sensor performs the cylinder identification.
      Accelerator Pedal Position Sensor Linear (Non-contact) Type 1 This sensor detects the amount of pedal effort applied to the accelerator pedal.
      Throttle Position Sensor Linear (Non-contact) Type 1 This sensor detects the throttle valve opening angle.
      Knock Control Sensor Built-in Piezoelectric Type (Non-resonant Type/Flat Type) 1 This sensor detects an occurrence of engine knocking indirectly from the vibration of the cylinder block caused by the occurrence of engine knocking.
      Air Fuel Ratio Sensor*1 Heated Type (Planar Type) 1 As with the oxygen sensor, this sensor detects the oxygen concentration in the exhaust emissions. However, it detects the oxygen concentration in the exhaust emissions linearly.
      Oxygen Sensor*2 Heated Type (Cup Type) 1 This sensor detects the oxygen concentration in the exhaust emissions by measuring the electromotive force which is generated in the sensor itself.
      Variable Resistor*3 Variable Resistor 1 This is a variable resistor to adjust the air-fuel ratio while the engine is idling. The idle CO value is adjusted to the specified value by rotating the rotor.
      Fuel Injector Assembly

      12-hole Type*2

      4-hole Type*3

      		 4 The fuel injector assembly is an electromagnetically-operated nozzle which injects fuel in accordance with signals from the ECM.

      • *1: Models compliant with EURO 3 and EURO 4 emission regulations

      • *2: Models with unleaded gasoline engine

      • *3: Models with leaded gasoline engine

  2. SYSTEM CONTROL


    1. The engine control system has the following features. The ECM controls these systems:

      System Outline
      Sequential Multiport Fuel Injection (SFI)

      • An L-type SFI system directly detects the intake air mass with a hot wire type intake mass air flow meter sub-assembly.

      • The fuel injection system is a sequential multiport fuel injection system.

      • Fuel injection takes two forms:


        • Synchronous injection, which always takes place with the same timing in accordance with the basic injection duration and an additional correction based on the signals provided by the sensors.

        • Non-synchronous injection, which takes place at the time an injection request based on the signals provided by the sensors is detected, regardless of the crankshaft position.


      • Synchronous injection is further divided into group injection during a cold start, and independent injection after the engine is started.
      Electronic Spark Advance (ESA)

      • Ignition timing is determined by the ECM based on signals from various sensors. The ECM corrects ignition timing in response to engine knocking.

      • This system selects the optimal ignition timing in accordance with the signals received from the sensors and sends the (IGT) ignition signal to the igniter.
      Electronic Throttle Control System-intelligent (ETCS-i) Optimally controls the throttle valve opening in accordance with the amount of accelerator pedal effort and the condition of the engine and the vehicle.
      Variable Valve Timing-intelligent (VVT-i) Controls the intake camshaft to an optimal valve timing in accordance with the engine condition.
      Fuel Pump Control

      • Fuel pump operation is controlled by signals from the ECM.

      • The fuel pump is stopped when the Supplemental Restraint System (SRS) airbags are deployed.*1
      Air Conditioning Cut-off Control*2 By turning the air conditioning compressor assembly on or off in accordance with the engine condition, driveability is maintained.
      Air Fuel Ratio Sensor*3 and Oxygen Sensor Heater Control*4 Maintains the temperature of the air fuel ratio sensors or oxygen sensors at an appropriate level to increase the detection accuracy of the exhaust gas oxygen concentration.
      Engine Immobiliser*5 Prohibits fuel delivery and ignition if an attempt is made to start the engine with an invalid key.
      Diagnosis When the ECM detects a malfunction, the ECM diagnoses and memorizes the failed section.
      Fail-safe When the ECM detects a malfunction, the ECM stops or controls the engine in accordance with the data already stored in memory.

      • *1: Models with SRS airbag system

      • *2: Models with air conditioning system

      • *3: Models compliant with EURO 3 and EURO 4 emission regulations

      • *4: Models with unleaded gasoline engine

      • *5: Models with engine immobiliser system

  3. FUNCTION


    1. VVT-i System


      1. The VVT-i system is designed to control the intake camshaft within a range of 35° (of crankshaft angle) to provide valve timing that is optimally suited to the engine condition. This improves torque in all the speed ranges as well as increasing fuel economy and reducing exhaust emissions.

        A01EZMME02
        Text in Illustration
        *1 Camshaft Position Sensor *2 Camshaft Timing Oil Control Valve Assembly
        *3 Engine Coolant Temperature Sensor *4 Crankshaft Position Sensor
        *5 ECM - -
        *a from Intake Mass Air Flow Meter Sub-assembly *b from Throttle Position Sensor
        A01EZG8E01

      2. The VVT-i system delivers excellent benefits in the different operating conditions as shown in the table below:

        Operation State Objective Effect
        During Idling A01EZ66E01 Eliminating overlap reduces blow back to the intake side.

        • Stabilized idling speed

        • Better fuel economy
        At Light Load A01EZN9E01 Decreasing overlap to reduce blow back to the intake side. Ensured engine stability
        At Medium Load A01EZP7E01 Increasing overlap to increase internal EGR to reduce pumping loss.

        • Better fuel economy

        • Improved emission control
        In Low to Medium Speed Range with Heavy Load A01EZ6TE01 Advancing the intake valve close timing for volumetric efficiency improvement. Improved torque in low to medium speed range
        In High Speed Range with Heavy Load A01EZCIE01 Retarding the intake valve close timing for volumetric efficiency improvement. Improved output
        At Low Temperatures A01EZ66E01 Decreasing overlap to reduce blow back to the intake side leads to the lean burning condition, and stabilizes the idling speed at fast idle.

        • Stabilized fast idle speed

        • Better fuel economy

        • Starting Engine

        • Stopping Engine

        		 A01EZ66E01 Decreasing overlap to reduce blow back to the intake side. Improved startability

    2. Electronic Throttle Control System-intelligent (ETCS-i)


      1. The ETCS-i is used, providing excellent throttle control in all the operating ranges. The accelerator cable has been discontinued, and an accelerator pedal position sensor has been provided on the accelerator pedal.

      2. In the conventional throttle body, the throttle valve opening is determined by the amount of the accelerator pedal effort. In contrast, the ETCS-i uses the ECM to calculate the optimal throttle valve opening that is appropriate for the respective driving condition and uses a throttle control motor to control the opening.

      3. The ETCS-i controls the idle speed control (ISC) system.

      4. In case of an abnormal condition, this system switches to the limp mode.

        A01EZ6SE01

    3. Fuel Pump Control


      1. The fuel pump is controlled by the ECM, using the circuit opening relay.

      2. The fuel pump control has a fuel cut control. The fuel cut control stops the fuel pump when any of the Supplemental Restraint System (SRS) airbags have deployed.*


        • *: Models with SRS airbag system

  4. CONSTRUCTION


    1. Air Fuel Ratio Sensor and Oxygen Sensor


      1. A planar type air fuel ratio sensor and a cup type oxygen sensor are used. The basic construction of the oxygen sensor and the air fuel ratio sensor is the same. However, they are divided into the cup type and the planar type, in accordance with the different types of heater construction used.

      2. The planar type air fuel ratio sensor uses alumina, which excels in heat conductivity and electrical insulation, to integrate the sensor element with a heater, thus improving the warmup performance of the sensor.

      3. The cup type oxygen sensor contains a sensor element that surrounds the heater.

        A01EZG2E01
        Text in Illustration
        *1 Diffusion Resistance Layer *2 Alumina
        *3 Platinum Electrode *4 Sensor Element (Zirconia)
        *5 Heater *6 Atmosphere
        *a Planar Type Air Fuel Ratio Sensor *b Cup Type Oxygen Sensor

      4. As illustrated below, the conventional oxygen sensor is characterized by a sudden change in its output voltage at the threshold of the stoichiometric air fuel ratio (14.7:1). In contrast, the air fuel ratio sensor data is approximately proportionate to the existing air fuel ratio. The air fuel ratio sensor converts the oxygen density to current and sends it to the ECM. As a result, the detection precision of the air fuel ratio has been improved. The air fuel ratio sensor data can be viewed using an intelligent tester II.

        A01EZAFE03

    2. Intake Mass Air Flow Meter Sub-assembly


      1. This engine uses the hot-wire type air flow meter designed for direct electrical measurement of the intake air mass flow.

      2. This intake mass air flow meter sub-assembly has a built-in intake air temperature sensor.

        A01EZ8EE01
        Text in Illustration
        *1 Intake Mass Air Flow Meter Sub-assembly *2 Temperature Sensing Element
        *3 Platinum Hot-wire Element *4 Intake Air Temperature Sensor
        A01EZJZ Air Flow - -

    3. Crankshaft and Camshaft Position Sensors


      1. The timing rotor of the crankshaft consists of 36 teeth, with 2 teeth missing. The crankshaft position sensor outputs the crankshaft rotation signals every 10°, and the missing teeth are used to determine the top dead center.

      2. To detect the camshaft position, a timing rotor on the intake camshaft is used to generate 3 pulses for every 2 revolutions of the crankshaft.

        A01EZS8E01
        Text in Illustration
        *1 Crankshaft Position Sensor *2 Timing Rotor
        *3 Camshaft Position Sensor - -
        A01EZ7ME02

    4. Knock Control Sensor (Flat Type)


      1. In a conventional type knock control sensor (resonant type), a vibration plate is built into the sensor. This plate has the same resonance point as the knocking* frequency of the engine block. This sensor can only detect vibration in this frequency band.


        • *: The term "knock" or "knocking" is used in this case to describe either preignition or detonation of the air fuel mixture in the combustion chamber. This preignition or detonation refers to the air fuel mixture being ignited earlier than is advantageous. This use of "knock" or "knocking" is not primarily used to refer to a loud mechanical noise that may be produced by an engine.

      2. A flat type knock control sensor (non-resonant type) has the ability to detect vibration in a wider frequency band (from approximately 6 kHz to 15 kHz). It has the following features:


        • The engine knocking frequency will vary slightly depending on the engine speed. The flat type knock control sensor can detect vibration even when the engine knocking frequency changes. Due to the use of the flat type knock control sensor, the vibration detection ability has been increased compared to a conventional type knock control sensor, and more precise ignition timing control is possible.

          A01EZ9ZE09

      3. A flat type knock control sensor is installed in an engine by placing it over the stud bolt installed on the cylinder block. For this reason, a hole for the stud bolt exists in the center of the sensor.

      4. In the sensor, a steel weight is located in the upper portion. An insulator is located between the weight and the piezoelectric element.

      5. An open/short circuit detection resistor is integrated in the sensor. When the ignition switch is ON, the open/short circuit detection resistor in the knock control sensor and the resistor in the ECM keep the voltage at terminal KNK1 constant. An Integrated Circuit (IC) in the ECM constantly monitors the voltage of terminal KNK1. If the open/short circuit occurs between the knock control sensor and the ECM, the voltage of terminal KNK1 will change and the ECM will detect the open/short circuit and store a Diagnostic Trouble Code (DTC).

        A01EZMAE18

      6. Vibrations caused by knocking are transmitted to the steel weight. The inertia of this weight applies pressure to the piezoelectric element. This action generates electromotive force.

        A01EZKIE01
        Text in Illustration
        *1 Steel Weight *2 Piezoelectric Element
        A01EZFI Inertia - -

      7. This sensor is mounted in the specific directions and angles illustrated. To prevent water accumulation in the connector, make sure to install the flat type knock control sensor in the position shown in the following illustration:

        A01EZOEE01
        Text in Illustration
        *1 Knock Control Sensor - -

    5. Throttle Position Sensor


      1. A non-contact type throttle position sensor is used. This sensor uses a Hall IC, which is mounted on the throttle body.

      2. The Hall IC is surrounded by a magnetic yoke. The Hall IC converts the changes that occur in the magnetic flux into electrical signals and outputs them as throttle valve effort to the ECM.

      3. The Hall IC contains circuits for the main and sub signals. It converts the throttle valve opening angles into electric signals with two differing characteristics and outputs them to the ECM.

        A01EZQTE01

    6. Accelerator Pedal Position Sensor


      1. This non-contact type accelerator pedal position sensor uses a Hall IC, which is mounted on the accelerator pedal arm.

      2. A magnetic yoke is mounted at the base of the accelerator pedal arm. This yoke rotates around the Hall IC in accordance with the amount of effort that is applied to the accelerator pedal. The Hall IC converts the changes in the magnetic flux that occur into electrical signals, and outputs them in the form of accelerator pedal position signals to the ECM.

      3. This accelerator pedal position sensor includes 2 Hall ICs and circuits for the main and sub signals. It converts the accelerator pedal depressed angles into electric signals with two differing characteristics and outputs them to the ECM.

        A01EZH2E04

    7. Camshaft Timing Oil Control Valve Assembly


      1. This camshaft timing oil control valve assembly controls the spool valve using duty cycle control from the ECM. This allows hydraulic pressure to be applied to the VVT-i controller advanced or retarded side. When the engine is stopped, the camshaft timing oil control valve assembly is in the most retarded position.

        A01EZ9DE01
        Text in Illustration
        *1 Spool Valve *2 Sleeve
        *3 Spring *4 Plunger
        *5 Coil - -
        *a To VVT-i Controller (Advance Side) *b To VVT-i Controller (Retard Side)
        *c Drain *d Oil Pressure

    8. Throttle Control Motor


      1. A DC motor with excellent response and minimal power consumption is used for the throttle control motor. The ECM performs the duty cycle control of the direction and the amperage of the current that flows to the throttle control motor in order to regulate the opening of the throttle valve.

        A01EZKCE01
        Text in Illustration
        *1 Throttle Body *2 Throttle Valve
        *3 Throttle Control Motor - -

    9. Ignition Coil Assembly


      1. The Direct Ignition System (DIS) provides 4 ignition coil assemblies, one for each cylinder. The spark plug caps, which provide contact to spark plugs, are integrated with the ignition coil. Also, an igniter is enclosed to simplify the system.

        A01EZ9SE01
        Text in Illustration
        *1 Igniter *2 Iron Core
        *3 Plug Cap *4 Secondary Coil
        *5 Primary Coil - -
        *a Ignition Coil Cross Section - -

    10. Spark Plug


      1. Long-reach type spark plugs are used. This type of spark plug allows the area of the cylinder head that receives the spark plugs to be made thick. Thus, the water jacket can be extended near the combustion chamber, which contributes to cooling performance.

        A01EZDDE01
        Text in Illustration
        *1 Long-reach Type Spark Plug *2 Conventional Type Spark Plug

      2. On models for Kazakhstan, iridium-tipped spark plugs are used. By making the center electrode of iridium, it is possible to achieve superior ignition performance and durability when compared to nickel-tipped spark plugs.

        A01EZG4E01
        Text in Illustration
        *1 Iridium Tip *2 Platinum Tip

  5. OPERATION


    1. VVT-i System


      1. Using the engine speed, intake air mass, throttle position and engine coolant temperature, the ECM can calculate optimal valve timing for each driving condition and controls the camshaft timing oil control valve assembly. In addition, the ECM uses signals from the camshaft position sensor and the crankshaft position sensor to detect the actual valve timing, thus providing feedback control to achieve the target valve timing.

        A01EZS2E01

      2. When the camshaft timing oil control valve assembly is positioned as illustrated below by the advance signals from the ECM, the resultant oil pressure is applied to the timing advance side vane chamber to rotate the camshaft in the timing advance direction:

        A01EZDAE02
        Text in Illustration (Advance Side Operation)
        *1 Vane *2 ECM
        *a Rotation Direction *b In (Oil Pressure)
        *c Drain (Oil Pressure) - -

      3. When the camshaft timing oil control valve assembly is positioned as illustrated below by the retard signals from the ECM, the resultant oil pressure is applied to the timing retard side vane chamber to rotate the camshaft in the timing retard direction:

        A01EZBWE02
        Text in Illustration (Retard Side Operation)
        *1 Vane *2 ECM
        *a Rotation Direction *b Drain (Oil Pressure)
        *c In (Oil Pressure) - -

      4. After reaching the target timing, the valve timing is held by keeping the camshaft timing oil control valve assembly in the neutral position unless the traveling state changes. This adjusts the valve timing at the desired target position and prevents the engine oil from running out when it is unnecessary.

    2. Fuel Pump Control


      1. On the models with SRS airbag system, when the ECM detects the airbag deployment signal from the center airbag sensor assembly, the ECM will turn the circuit opening relay off. After the fuel cut control has been activated, turning the ignition switch from off to ON cancels the fuel cut control, and the engine can be restarted.

        A01EZCKE01

    3. ETCS-i


      1. The ECM drives the throttle control motor by determining the target throttle valve opening in accordance with the respective operating condition.

      2. The ECM controls the throttle to an optimal throttle valve opening that is appropriate for the driving conditions such as the amount of accelerator pedal effort and the engine speed in order to achieve excellent throttle control and comfort in all operating ranges.

        A01EZK6E02

      3. The ECM controls the throttle valve in order to constantly maintain an ideal idle speed.