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, ETCS-i and EGR to suit the operating conditions of the engine in accordance with the signals provided by the sensors.
      Intake Mass Air Flow Meter Sub-assembly Mass Air Flow Meter 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 (built into the intake mass air flow meter sub-assembly).
      E. F. I. Engine Coolant Temperature Sensor Thermistor Type 1 This sensor detects the engine coolant temperature by means of an internal thermistor.
      Crank Position Sensor [No. of Rotor Teeth] Pick-up Coil Type [36 - 2] 1 This sensor detects the engine speed and performs cylinder identification.
      Camshaft Position Sensor [No. of Rotor Teeth] Magneto- Resistance Element (MRE) Type [3] 1 This sensor performs cylinder identification and detects the VVT angle.
      Throttle Body with Motor Assembly 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 Heated Type (Planar Type) 1 As with the oxygen sensor, this sensor detects the oxygen concentration in the exhaust gas. However, it detects the oxygen concentration in the exhaust gas linearly.
      Oxygen Sensor Heated Type (Cup Type) 1 This sensor detects the oxygen concentration in the exhaust gas by measuring the electromotive force which is generated in the sensor itself.
      Fuel Injector Assembly 12-hole Type 4 The injector is an electromagnetically-operated nozzle which injects fuel in accordance with signals from the ECM.

  2. SYSTEM CONTROL

    1. The engine control system of the 2AR-FXE engine has the following features.

      System Outline
      Sequential Multiport Fuel Injection (SFI)

      • This is an L-type SFI system. It 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 2 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 grouped 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 (IGT) ignition signals to the igniters.
      Electronic Throttle Control System-intelligent (ETCS-i) Optimally controls the opening angle of the throttle valve in accordance with the accelerator pedal input and the engine and vehicle operating conditions.
      Variable Valve Timing-intelligent (VVT-i) Controls the camshaft (intake) to the optimal valve timing in accordance with engine operating conditions.
      Water Pump Control Engine water pump assembly operation is controlled by signals from the ECM.
      Fuel Pump Control

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

      • The fuel pump is stopped when an SRS airbag is deployed in a frontal, side, or rear side collision.
      Cooling Fan Control Radiator cooling fan operation is controlled by signals from the cooling fan ECU based on the E. F. I. engine coolant temperature sensor signal and the operating condition of the air conditioning.
      Air Fuel Ratio Sensor and Oxygen Sensor Heater Control Maintains the temperature of the air fuel ratio sensor or oxygen sensor at an appropriate level to increase the ability of the sensor to accurately detect the concentration of oxygen.

      Exhaust Gas Recirculation (EGR) Control

      (For details, Click here

      		Based on the signals received from the sensors, the ECM determines the EGR volume in accordance with engine operating conditions.
      Evaporative Emission Control The ECM controls the purge flow of evaporative emissions (HC) from the canister in accordance with engine operating conditions.
      Fail-safe When the ECM detects a malfunction, the ECM stops or controls the engine according to the data already stored in memory.
      Diagnosis When the ECM detects a malfunction, the ECM records the malfunction and information that relates to the fault.

  3. FUNCTION

    1. VVT-i System

      1. The VVT-i system is designed to control the intake camshaft within a range of 45° (of Crankshaft Angle) to provide valve timing that is optimally suited to the engine operating condition. This improves torque in all engine speed ranges as well as increasing fuel economy, and reducing exhaust emissions.

        A011Z8PE01
        Text in Illustration
        *1 Camshaft Timing Oil Control Valve Assembly *2 Camshaft Position Sensor
        *3 E. F. I. Engine Coolant Temperature Sensor *4 ECM
        *5 Crank Position Sensor *6 Intake Mass Air Flow Meter Sub-assembly
        *7 Throttle Position Sensor - -
        A011ZAUE01
        Text in Illustration
        *a VVT-i Operation Range (Intake) *b TDC
        *c BDC *d Intake Valve Opening Angle
        *e Exhaust Valve Opening Angle - -

    2. Fuel Pump Control

      1. The fuel pump is controlled by the ECM. Fuel pump control has a fuel cut control function. Fuel cut control stops the fuel pump when any of the SRS airbags has deployed.

    3. Water Pump Control

      1. The ECM regulates the amount of engine coolant circulation to suit the engine operating conditions. The ECM bases this control on signals such as the engine coolant temperature, vehicle speed and engine speed. As a result, the engine will be warmed up more quickly, and cooling loss will be reduced as well.

    4. Cooling Fan Control System

      1. The cooling fan control system achieves an optimal fan speed in accordance with the engine coolant temperature, vehicle speed, engine speed, and air conditioning operating conditions.

  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, according to 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 a sensor element with a heater, thus improving the warm-up performance of the sensor.

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

        A011ZFLE01
        Text in Illustration
        *1 Air Fuel Ratio Sensor (Planar Type) *2 Oxygen Sensor (Cup Type)
        *3 Platinum Electrode *4 Alumina
        *5 Sensor Element (Zirconia) *6 Atmosphere
        *7 Heater *8 Diffusion Resistance Layer

      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 the Techstream.

        A011ZMIE22

    2. Intake Mass Air Flow Meter Sub-assembly

      1. The intake mass air flow meter sub-assembly, which is a slot-in type, allows a portion of the intake air to flow through the detection area. By directly measuring the mass and the flow rate of the intake air, the detection precision is improved and the intake air resistance is reduced.

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

        A011ZOGE04
        Text in Illustration
        *1 Platinum Hot-wire Element *2 Temperature Sensing Element
        *3 Intake Air Temperature Sensor - -
        *a A-A Cross Section - -
        A011ZI5 Air Flow - -

    3. Crank Position Sensor

      1. The timing rotor of the crankshaft consists of 34 teeth with 2 teeth missing. The crank position sensor outputs the crankshaft rotation signals every 10°, and the change of the signal due to the missing teeth is used to determine top-dead-center.

        A011ZLWE06

    4. Camshaft Position Sensor

      1. A Magneto-Resistance Element (MRE) type camshaft position sensor is used. To detect the camshaft position, a timing rotor that is part of the camshaft is used to generate 6 (3 high output, 3 low output) pulses for every 2 revolutions of the crankshaft.

        A011ZCCE01

      2. The MRE type camshaft position sensor consists of an MRE, a magnet and a sensor. The direction of the magnetic field changes due to the profile (protruding and non-protruding portions) of the timing rotor, which passes by the sensor. As a result, the resistance of the MRE changes, and the output voltage to the ECM changes to high or low. The ECM detects the camshaft position based on this output voltage.

        A011ZDLE04

    5. Knock Control Sensor (Flat Type)

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

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

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

        • An open/short circuit detection resistor is integrated in the sensor.

      2. 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 is increased compared to a conventional type knock control sensor, and more precise ignition timing control is possible.

        A011ZDAE11

      3. An open/short circuit detection resistor is integrated in the sensor. When the ignition is ON, the open 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 an open or short circuit occurs between the knock control sensor and the ECM, the voltage of terminal KNK1 will change and the ECM will detect this and store a Diagnostic Trouble Code (DTC).

        A011ZOFE20

      4. 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.

        A011ZN6E01
        Text in Illustration
        *1 Steel Weight *2 Inertia
        *3 Piezoelectric Element - -

    6. Throttle Position Sensor

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

        • The Hall IC is surrounded by a magnet. The Hall IC converts the changes that occur in the magnetic flux into electrical signals, and outputs them in the form of throttle valve position signals to the ECM.

        • The Hall IC contains circuits for the main and sub signals. It converts the throttle valve opening angle into electric signals that have differing characteristics, and outputs them to the ECM.

          A011ZBBE01

          Tech Tips

          The inspection method differs from a contact type throttle position sensor because this non-contact type throttle position sensor uses a Hall IC. For details, refer to the Repair Manual.

    7. Camshaft Timing Oil Control Valve Assembly

      1. The camshaft timing oil control valve assembly controls its spool valve using duty-cycle control from the ECM. This allows hydraulic pressure to be applied to the camshaft timing gear assembly advance or retard side. When the engine is stopped, the camshaft timing oil control valve assembly will move to the retard position.

        A011ZGLE01
        Text in Illustration
        *1 Spring *2 Sleeve
        *3 Drain *4 Oil Pressure
        *5 Spool Valve *6 Plunger
        *7 Coil - -
        *a To Camshaft Timing Gear Assembly (Advance Side) *b To Camshaft Timing Gear Assembly (Retard Side)

    8. Ignition Coil Assembly

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

        A011ZMOE01
        Text in Illustration
        *1 Igniter *2 Iron Core
        *3 Primary Coil *4 Secondary Coil
        *5 Plug Cap - -

    9. Spark Plug

      1. Long-reach type spark plugs are used. This type of spark plug allows the area of the cylinder head sub-assembly 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.

      2. Iridium-tipped spark plugs are used to achieve a 192000 km (120000 miles) or 100000 km (62140 miles)* maintenance interval. By making the center electrode of iridium, it is possible to achieve superior ignition performance and durability when compared to platinum-tipped spark plugs.

        *: Destination package for South Korea

        A011ZI4E01
        Text in Illustration
        *1 Water Jacket *2 Iridium Tip
        *3 Platinum Tip - -

  5. OPERATION

    1. VVT-i System

      1. Based on engine speed, intake air volume, throttle position and engine coolant temperature, the ECM calculates optimal valve timing for all driving conditions. The ECM also controls the camshaft timing oil control valve assembly. In addition, the ECM uses signals from the camshaft position sensor and the crank position sensor to detect the actual valve timing, thus providing feedback control to achieve the target valve timing.

        A011ZHAE01

      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.

        A011ZG0E01
        Text in Illustration
        *1 Vane *2 ECM
        *a Rotation Direction *b Oil Pressure
        *c In *d Drain

      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.

        A011ZCFE01
        Text in Illustration
        *1 Vane *2 ECM
        *a Rotation Direction *b Oil Pressure
        *c In *d Drain

      4. After reaching the target timing, the engine valve timing is maintained by keeping the camshaft timing oil control valve assembly in the neutral position unless the engine operating conditions change. This maintains the engine valve timing at the desired target position by preventing the engine oil from running out of the camshaft timing oil control valve assembly.

    2. Fuel Pump Control

      1. The fuel pump is controlled by the ECM. Fuel pump control has a fuel cut control function. Fuel cut control stops the fuel pump when any of the SRS airbags has deployed.

        • When the ECM detects the airbag deployment signal from the airbag sensor assembly, the ECM will turn the circuit opening relay off. After fuel cut control has been activated, turning the power switch from off to on (IG) cancels fuel cut control, and the engine can be restarted.

          A011ZHRE01

    3. Cooling Fan Control System

      1. The cooling fan control system achieves an optimal fan speed in accordance with the engine coolant temperature, vehicle speed, engine speed, and air conditioning operating conditions. The ECM calculates the appropriate fan speed and sends the signals to the cooling fan ECU. Upon receiving the signals from the ECM, the cooling fan ECU actuates the fan motors.

        A011ZCNE01

      2. As illustrated below, the ECM determines the required cooling fan speed by selecting the fastest fan speed from among the following:

        1. The fan speed required according to the engine coolant temperature (Graph 1).

        2. The fan speed required based on the air conditioning refrigerant pressure (Graph 2).

          • When the air conditioning refrigerant pressure is within the lower part of the normal operating range with the air conditioning pressure sensor on, the required fan speed differs according to the vehicle speed.

          • When the air conditioning refrigerant pressure is higher than a specified upper limit, the required fan speed will increase based on an emergency request from the ECM.

        A011ZLAE01

    4. Water Pump Control

      1. Since this engine is stopped and restarted repeatedly by the hybrid system, by providing an electric engine water pump assembly, coolant temperatures while the engine is operating will be stable, and shutting off the power to the pump motor will contribute to fuel economy.

      2. The ECM receives the pump motor rotation pulse signal from the water pump driver circuit and the engine water pump assembly required flow quantity signal from the air conditioning amplifier assembly. Based on these, the ECM determines the pump motor speed required to obtain the coolant flow amount that corresponds to the operating conditions at that time.

        A011ZNLE02

  6. FAIL-SAFE

    1. When a malfunction of any of the sensors is detected, there is a possibility of an engine or other malfunction occurring if the ECM were to continue normal control. To prevent such a problem, the fail-safe function of the ECM either relies on the data stored in memory to allow the engine control system to continue operating, or stops the engine if a hazard is anticipated. For details, refer to the Repair Manual.

  7. DIAGNOSIS

    1. When the ECM detects a malfunction, the ECM records information related to the fault. Furthermore, the Malfunction Indicator Lamp (MIL) in the combination meter assembly illuminates to inform the driver.

    2. The ECM also stores Diagnostic Trouble Codes (DTCs) for malfunctions it has detected. The DTCs can be accessed by using the Techstream.

    3. A permanent DTC is used for the DTCs associated with the illumination of the MIL. The permanent DTCs cannot be cleared by using the Techstream or disconnecting the battery terminal.

    4. For details, refer to the Repair Manual.