SFI SYSTEM


  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.
      Oxygen Sensor (Bank 1, Sensor 2) Cup Type with Heater 1 This sensor detects the oxygen concentration in the exhaust emission by measuring the electromotive force generated in the sensor itself.
      Air Fuel Ratio Sensor (Bank 1, Sensor 1) Planar Type with Heater 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.
      Intake Air Flow Meter Sub-assembly Hot-wire Type 1 This sensor has a built-in hot-wire to directly detect the intake air mass and flow rate.
      Crank Position Sensor (Rotor Teeth) Pick-up Coil Type (36-2) 1 This sensor detects the engine speed and the crankshaft position.
      Cam Position Sensor (Rotor Teeth) Pick-up Coil Type (3) 2 This sensor detects the camshaft position and performs the cylinder identification.
      Engine Coolant Temperature Sensor Thermistor Type 1 This sensor detects the engine coolant temperature by means of an internal thermistor.
      Intake Air Temperature Sensor Thermistor Type 1 This sensor detects the intake air temperature by means of an internal thermistor.
      Knock Control Sensor Built-in Piezoelectric Element (Flat Type) 1 This sensor detects an occurrence of the engine knocking indirectly from the vibration of the cylinder block caused by the occurrence of engine knocking.
      Throttle Position Sensor Hall IC Type (Non-contact Type) 1 This sensor detects the throttle valve opening angle.
      Accelerator Pedal Position Sensor Hall IC Type (Non-contact Type) 1 This sensor detects the amount of pedal effort applied to the accelerator pedal.
      Fuel Injector Assembly 12-hole Type 4 The fuel injector assembly is an electromagnetically-operated nozzle which injects fuel in accordance with the signals from the ECM.

  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 mass air flow meter.

      • The fuel injection system is a sequential multiport fuel injection system.
      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 throttle valve opening in accordance with the amount of accelerator pedal effort, the throttle valve opening control request from the ECM, and the condition of the engine and the vehicle.
      Dual VVT-i (Dual Variable Valve Timing-intelligent) Optimal valve timing can be controlled by the intake and exhaust camshafts according to engine conditions.
      Fuel Pump Control

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

      • The fuel pump is stopped when any of the Supplemental Restraint System (SRS) airbags are deployed.
      Air Conditioning Cut-off Control By turning the air conditioning compressor assembly on or off in accordance with the engine condition, driveability is maintained.
      Starter Control* Once the engine switch is pushed, this control continues to operate the starter until the engine has started.
      Air Fuel Ratio Sensor and Oxygen Sensor Heater Control 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.
      Air Injection System The ECM controls the air injection time based on the signals from the air flow meter and water temperature sensor. For details, see 2TR-FE EMISSION CONTROL section.
      Engine Immobiliser Prohibits fuel delivery and ignition if an attempt is made to start the engine with an invalid key.
      Brake Override System The driving torque is restricted when both the accelerator and brake pedals are depressed. (For the activation conditions and inspection method, refer to the Repair Manual.)
      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.

      • *: Models with entry and start system

  3. FUNCTION


    1. Dual VVT-i System


      1. The Dual Variable Valve Timing-intelligent (Dual VVT-i) system is designed to control the intake and exhaust camshafts within a range of 36° and 45° respectively (of crankshaft angle) to provide valve timing that is optimally suited to the engine operating conditions. This improves torque in all the speed ranges as well as increasing fuel economy and reducing exhaust emissions.

        B001BI8E03
        Text in Illustration
        *1 Camshaft Timing Oil Control Valve Assembly (Exhaust) *2 Cam Position Sensor (Intake)
        *3 Crank Position Sensor *4 Engine Coolant Temperature Sensor
        *5 Camshaft Timing Oil Control Valve Assembly (Intake) *6 Cam Position Sensor (Exhaust)
        *7 ECM *8 Intake Mass Air Flow Meter Sub-assembly
        *9 Throttle Position Sensor - -
        B001BQCE05

      2. The Dual VVT-i system delivers excellent benefits in the different operating conditions as follows:


        1. During Idling

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        2. At Light Load

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        3. At Medium Load

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        4. In Low to Medium Speed Range with Heavy Load

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        5. In High Speed Range with Heavy Load

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        6. At Low Temperatures

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        7. Starting and Stopping Engine

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    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, Brake Control system and cruise control system*.


        • *: Models with cruise control system

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

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    3. Fuel Pump Control


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

    4. Starter Control (Models with Entry and Start System)


      1. Once the engine switch is pressed, this function operates the starter until the engine starts, provided that the clutch pedal is depressed.

      2. This prevents application of the starter for an inadequate length of time and also prevents the engine from being cranked after it has started.

  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 the heater, thus improving the warmup performance of the sensor.

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

        B001BJJE04
        Text in Illustration
        *A Planar Type Air Fuel Ratio Sensor *B Cup Type Oxygen Sensor
        *1 Diffusion Resistance Layer *2 Alumina
        *3 Atmosphere *4 Heater
        *5 Platinum Electrode *6 Sensor Element (Zirconia)

      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 Global TechStream (GTS).

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    2. Intake Air Flow Meter Sub-assembly


      1. This Intake 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 Air Flow Meter Sub-Assembly has a built-in intake air temperature sensor.

        B001BOIE02
        Text in Illustration
        *1 Intake Air Temperature Sensor - -
        B001BOY Air Flow - -

    3. Crankshaft and Cam Position Sensors


      1. A pick-up coil type crank position sensor, Magnetic Resistance Element (MRE) type intake and exhaust cam position sensors are used.

      2. To detect each cam position, a timing rotor that is secured to the intake camshaft in front of the VVT-i controller and installed on the exhaust camshaft are used to generate 3 high output and 3 low output signals for every 2 revolutions of the crankshaft.

        B001BN0E05
        Text in Illustration
        *1 Crankshaft Position Sensor *2 Timing Rotor
        *3 Cam Position Sensor (Intake) *4 Cam Position Sensor (Exhaust)

      3. 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 missing teeth are used to determine the top dead center.

        B001BMPE04
        *a - Sensor Output Waveforms -
        *b 2 Teeth Missing

    4. Knock Control Sensor


      1. A flat type knock control sensor (non-resonant type) is used.

      2. 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 vibrations in this frequency band.


        • *: The term "knock" or "knocking" is used in this case to describe either pre-ignition or detonation of the air fuel mixture in the combustion chamber. This pre-ignition 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.

      3. The flat type knock control sensor (non-resonant type) has the ability to detect vibrations 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 vibrations even when the engine knocking frequency changes. Due to the use of a flat type knock control sensor, vibration detection ability has been increased compared to a conventional type knock control sensor, and more precise ignition timing control is possible.

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      4. A flat type knock control sensor is installed to 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.

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

      6. 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).

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      7. 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.

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

      8. 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:

        B001B7RE02
        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 2 differing characteristics and outputs them to the ECM.

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    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 depression angles into electric signals with 2 differing characteristics and outputs them to the ECM.

      4. On the models with automatic transmission, when the depressing force applied to the accelerator pedal is greater than a predetermined amount, the ECM detects a "kick down mode" from the VPA1 signal provided by the accelerator pedal position sensor.

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    7. Camshaft Timing Oil Control Valve Assembly


      1. This camshaft timing oil control valve 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 intake side camshaft timing oil control valve is in the most retarded position, and the exhaust side camshaft timing oil control valve is in the most advanced position.

        B001BY2E03
        Text in Illustration
        *1 Spool Valve *2 Sleeve
        *3 Spring - -
        *a Camshaft Timing Oil Control Valve Assembly (Intake) *b To Intake VVT-i Controller (Advance Side)
        *c To Intake VVT-i Controller (Retard Side) *d Drain
        *e In - -
        B001BOY Oil Pressure - -
        B001BH5E03
        Text in Illustration
        *1 Spool Valve *2 Sleeve
        *3 Spring - -
        *a Camshaft Timing Oil Control Valve Assembly (Exhaust) *b To Exhaust VVT-i Controller (Retard Side)
        *c To Exhaust VVT-i Controller (Advance Side) *d Drain
        *e In - -
        B001BOY 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.

        B001BZ8E02
        Text in Illustration
        *1 Throttle with Motor Body Assembly *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 the spark plugs, are integrated with the ignition coil assembly. Also, an igniter is enclosed to simplify the system.

        B001BZOE05
        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.

      2. By using an iridium center electrode, ignition performance superior to that of platinum-tipped spark plugs has been achieved and durability has been increased.

        B001BV4E03
        Text in Illustration
        *1 Iridium Tip *2 Platinum Tip
        *a Long-reach *b Center Electrode : 0.55 mm
        *c Plug Gap : 0.7 mm to 0.8 mm (0.0276 in to 0.0315 in) - -

  5. OPERATION


    1. Dual VVT-i System


      1. Based on engine speed, intake air mass, 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.

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      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:

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        Text in Illustration
        *1 Vane *2 Camshaft Timing Oil Control Valve Assembly (Intake)
        *3 ECM *4 Camshaft Timing Oil Control Valve Assembly (Exhaust)
        *a Intake Side *b Exhaust Side
        *c Advance Side Vane Chamber *d In
        *e Drain - -
        B001BOY Oil Pressure B001B9L Rotation Direction

      3. When the camshaft timing oil control valve 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:

        B001BSEE02
        Text in Illustration
        *1 Vane *2 Camshaft Timing Oil Control Valve Assembly (Intake)
        *3 ECM *4 Camshaft Timing Oil Control Valve Assembly (Exhaust)
        *a Intake Side *b Exhaust Side
        *c Retard Side Vane Chamber *d In
        *e Drain - -
        B001BOY Oil Pressure B001B9L Rotation Direction

      4. After reaching the target timing, the valve timing is held by keeping the camshaft timing oil control valve 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. When the ECM detects the Supplemental Restraint System (SRS) 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.

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    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.

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

      4. As part of the TRC, the throttle valve opening angle is reduced by a demand signal sent from the skid control ECU to the ECM. This demand signal is sent if an excessive amount of slippage occurs at a drive wheel, thus ensuring vehicle stability and applying an appropriate amount of power to the road.

      5. In order to bring the effectiveness of the VSC into full play, the throttle valve angle is regulated through a coordination control by the skid control ECU and the ECM.

      6. On the models with cruise control system, the ECM directly actuates the throttle valve for operation of the cruise control.

    4. Starter Control (Models with Entry and Start System)


      1. When the driver pushes the engine switch once and the power management control ECU detects a start signal, the power management control ECU will output ACCD and STAR signals and begin cranking. Also, the driver can continue cranking for up to 30 seconds by pushing and holding the engine switch.

      2. If the engine speed reaches approximately 500 rpm, the ECM will judge that the engine has started and will send a signal to the power management control ECU using CAN communication. The power management control ECU will then stop the operation of the starter.

      3. If CAN communication is cut between the power management control ECU and the ECM, the power management control ECU will receive an engine speed signal (NE) directly from the ECM and will stop the operation of the starter.

      4. This system will cut off the power current which activates the accessories while the engine is being cranked. This prevents the intermittent blinking of the accessory lights caused by the voltage instability that occurs during engine cranking.

      5. This system has the following protections:


        • The starter will not operate if the engine is operating normally.

        • If the engine switch is pushed and held, cranking will stop once the engine speed reaches a pre-determined level. This prevents the starter from over-revving.

        • If the engine does not start even after approximately 6 seconds of starter operation, the power management control ECU will cancel the starter relay output. Furthermore, if the engine does not start after the engine switch has been pushed and held and cranking has continued for 30 seconds, cranking will be canceled in order to protect the starter.

        • It will not be possible to operate the starter for 2 seconds after engine starting has failed and cranking has been canceled. This helps to protect the starter.

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