SFI SYSTEM DETAILS


  1. FUNCTION OF MAIN COMPONENTS


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

      Components 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.
      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.
      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 for Intake [Rotor Teeth] Magneto-Resistance Element (MRE) Type [3] 2 (1 each bank) This sensor performs cylinder identification.
      Throttle Position Sensor Linear (Non-contact) Type 1 This sensor detects the throttle valve opening angle.

      Knock Control Sensor

      (Bank 1 and Bank 2)

      Built-in Piezoelectric Type

      (Non-resonant Type/Flat Type)

      		 2 (1 each bank) This sensor detects an occurrence of the engine knocking indirectly from the vibration of the cylinder block caused by the occurrence of engine knocking.

      Air Fuel Ratio Sensor

      (Bank 1, Sensor 1)

      (Bank 2, Sensor 1)

      		 Heated Type (Planar Type) 2 (1 each bank) As with the oxygen sensor, this sensor detects the oxygen concentration in the exhaust emission. However, it detects the oxygen concentration in the exhaust emission linearly.

      Heated Oxygen Sensor

      (Bank 1, Sensor 2)

      (Bank 2, Sensor 2)

      		 Heated Type (Cup Type) 2 (1 each bank) This sensor detects the oxygen concentration in the exhaust emission by measuring the electromotive force which is generated in the sensor itself.
      Fuel Injector Assembly 12-hole Type 6 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 2GR-FXE engine has the following features. The ECM that controls this system is made by DENSO.

      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 mass air flow meter.

      • 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 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 (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 conditions.
      Variable Valve Timing-intelligent (VVT-i) Controls the intake camshafts to an optimal valve timing in accordance with the engine operating conditions.
      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 The cooling fan ECU steplessly controls the speed of the fans in accordance with the engine coolant temperature, vehicle speed, engine speed, air conditioning operating conditions, and hybrid system coolant temperature. As a result, the cooling performance is improved.
      Air Fuel Ratio Sensor and Heated Oxygen Sensor Heater Control Maintains the temperature of the air fuel ratio sensors or heated oxygen sensors at an appropriate level to increase the ability of the sensors to accurately detect the oxygen concentration.

      Cooled 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 (For details Click here

      		The ECM controls the purge flow of evaporative emissions (HC) from the canister in accordance with engine 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.

      *: Models with cooled EGR control

  3. FUNCTION


    1. VVT-i System


      1. The Variable Valve Timing-intelligent (VVT-i) system is designed to control the intake camshafts within a range of 40° respectively (of Crankshaft Angle) to provide valve timing that is optimally suited to the operating conditions of this Atkinson cycle engine. This improves efficiency in all speed ranges, increasing fuel economy, and reducing exhaust emissions.

        A019WW0E01
        Text in Illustration
        *1 Camshaft Timing Oil Control Valve Assembly (Intake RH) *2 Engine Coolant Temperature Sensor
        *3 Camshaft Timing Oil Control Valve Assembly (Intake LH) *4 Camshaft Position Sensor (Intake LH)
        *5 Crankshaft Position Sensor *6 Camshaft Position Sensor (Intake RH)
        *7 ECM *8

        • Mass Air Flow Meter

        • Throttle Position Sensor

      2. The VVT-i system delivers excellent benefit in the different vehicle states as shown in the table below.

        Operation State Objective Effect

        • During Idling

        • At Light Load

        		 A019WROE03 Eliminating overlap reduces blow back to the intake side.

        • Stabilized idling rpm

        • Better fuel economy
        At Medium Load A019WPLE02 Increasing overlap increases internal EGR, reducing pumping losses.

        • Better fuel economy

        • Improved emission control
        In Low to Medium Speed Range with Heavy Load A019WAAE02 Advancing the intake valve closing timing improves volumetric efficiency. Improved torque in low to medium speed ranges
        In High Speed Range with Heavy Load A019WP9E02 Retarding the intake valve closing timing improves volumetric efficiency. Improved output
        At Low Temperatures A019WROE03 Eliminating overlap to reduce blow back to the intake side stabilizes the idling speed at fast idle.

        • Stabilized fast idle rpm

        • Better fuel economy

        • Upon Starting

        • Stopping the Engine

        		 A019WROE03 Eliminating overlap minimizes blow back to the intake side. Improved startability

    2. Fuel Pump Control


      1. The fuel pump is controlled by the ECM, using the fuel pump relay and the fuel pump resistor. The fuel pump control has a fuel cut control that operates when the SRS airbag deploys. The fuel cut control stops the fuel pump when any of the SRS airbags have deployed.

    3. Cooling Fan Control System


      1. A cooling fan control system controlled to achieve an optimal fan speed in accordance with the engine coolant temperature, vehicle speed, engine speed, air conditioning operating conditions, and hybrid system coolant temperature.

  4. CONSTRUCTION


    1. Mass Air Flow Meter


      1. The mass air flow meter, 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 mass air flow meter has a built-in intake air temperature sensor.

        A019WKIE01
        Text in Illustration
        *1 Platinum Hot-wire Element *2 Temperature Sensing Element
        *3 Intake Air Temperature Sensor - -
        *a Air Flow *b A - A Cross Section

    2. Crankshaft Position Sensor


      1. The timing rotor of the crankshaft consists of 34 teeth with 2 teeth missing. The crankshaft 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.

        A019WCSE04
        Text in Illustration
        *1 Timing Rotor *2 Crankshaft Position Sensor
        *a Engine Front *b Crank Position Sensor Signal Plate (720° CA)
        *c 10° CA *d 2 Teeth Missing

    3. Camshaft Position Sensor


      1. Magneto-Resistance Element (MRE) type intake camshaft position sensors are used. To detect each intake camshaft position, a timing rotor that is secured to the intake camshaft in front of the camshaft timing gear assembly is used to generate 6 (3 Hi Output, 3 Lo Output) pulses for every 2 revolutions of the crankshaft.

        A019WTSE01

      2. An 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 Hi or Lo. The ECM detects the camshaft position based on this output voltage.

        A019WUFE03

    4. Throttle Position Sensor


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


        • 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 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.

          A019WAQE04

          Tech Tips

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

    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.

        A019WWBE06

      3. An open/short circuit detection resistor is integrated in the sensor. When the power source is IG-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).

        A019WD8E05

      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.

        A019WHYE04
        Text in Illustration
        *1 Steel Weight *2 Piezoelectric Element
        *a Inertia - -

      5. These knock control sensors are mounted in the specific directions and angles as illustrated. To prevent the right and left bank connectors from being interchanged, make sure to install each sensor in its prescribed direction.

        A019WQWE03
        Text in Illustration
        *1 Knock Control Sensor (KNK1) *2 Knock Control Sensor (KNK2)
        *a Engine Front - -

    6. Air Fuel Ratio Sensor and Heated Oxygen Sensor


      1. A planar type air-fuel ratio sensor and a cup type heated oxygen sensor are used. The basic construction of the heated 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 heated oxygen sensor contains a sensor element that surrounds a heater.

        A019WQ0E02
        Text in Illustration
        *A Air Fuel Ratio Sensor (Planar Type) *B Heated Oxygen Sensor (Cup Type)
        *1 Diffusion Resistant Layer *2 Atmosphere
        *3 Heater *4 Platinum Electrode
        *5 Alumina *6 Sensor Element (Zirconia)

      4. As illustrated below, the conventional heated 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 intelligent tester.

        A019WVHE08

    7. Camshaft Timing Oil Control Valve Assembly


      1. This 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 (intake) will move to the retard position.

        A019WE5E04
        Text in Illustration
        *1 Spool Valve *2 Sleeve
        *3 Spring *4 Plunger
        *5 Coil - -
        *a To Camshaft Timing Gear Assembly (Advance Side) *b To Camshaft Timing Gear Assembly (Retard Side)
        *c Drain *d Oil Pressure

    8. Ignition Coil Assembly


      1. The Direct Ignition System (DIS) provides 6 ignition coil assemblies, one for each cylinder. The spark plug caps, which provide contact to spark plugs, are integrated with the ignition coil assembly. Also, an igniter is enclosed to simplify the system.

        A019WINE02
        Text in Illustration
        *1 Igniter *2 Secondary Coil
        *3 Iron Core *4 Primary Coil
        *5 Plug Cap - -

    9. Spark Plug


      1. Long-reach type spark plugs are used. This type of spark plugs allows the area of the cylinder head sub-assembly that receive 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 90000 km (54000 mile) 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.

        A019WW8E02
        Text in Illustration
        *1 Water Jacket *2 Iridium Tip
        *3 Platinum Tip - -
        *a Long-reach Type *b Conventional Type

  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 assemblies. In addition, the ECM uses signals from the camshaft position sensors and the crankshaft position sensor to detect the actual valve timing, thus providing feedback control to achieve the target valve timing.

        A019WAZE02

      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.

        A019WBKE01
        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.

        A019WMJE01
        Text in Illustration
        *1 Vane *2 ECM
        *a Rotation Direction *b Oil Pressure
        *c Drain *d In

      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, using the fuel pump relay and the fuel pump resistor. The fuel pump control has a fuel cut control that operates when the SRS deploys. The fuel cut control stops the fuel pump when any of the SRS airbags have deployed.


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

          A019WBCE01

    3. Cooling Fan Control System


      1. A cooling fan control system controlled to achieve an optimal fan speed in accordance with the engine coolant temperature, vehicle speed, engine speed, air conditioning operating conditions and hybrid system coolant temperature. The ECM calculates the appropriate fan speed and sends signals to cooling fan ECU No. 1 and No. 2. Upon receiving signals from the ECM, cooling fan ECU No. 1 and No. 2 independently actuates the No. 1 and No. 2 fan motors.

        A019WNTE02

      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 according to the engine speed (Graph 2).

        3. The fan speed required based on the air conditioning refrigerant pressure (Graph 3).


          • When the air conditioning refrigerant pressure is within the lower part of the normal operating range with the A/C switch 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.

        4. The fan speed required according to the hybrid system coolant temperature (Graph 4).

          A019WJQE01

  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 or blinks to inform the driver.

    2. The ECM will also store the Diagnostic Trouble Codes (DTCs) of the malfunctions. The DTCs can be accessed by using an intelligent tester.

    3. To clear a DTC that is stored in the ECM, use an intelligent tester, disconnect the cable from the negative (-) battery terminal, or remove the EFI No. 1 fuse and ETCS fuse for 1 minute or longer.

    4. For details, refer to the Repair Manual.