SFI SYSTEM DETAILS


  1. FUNCTION OF MAIN COMPONENTS


    1. System Control Table


      1. The main components of the 2ZR-FXE engine control system are as follows.

        Components Outline Quantity Function
        ECM 32-bit CPU 1 The ECM optimally controls the SFI, ESA, and ETCS-i to suit the operating conditions of the engine in accordance with the signals provided by the sensors.
        Crank Position Sensor (Rotor Teeth)

        Pick-up Coil Type

        (36 - 2)

        		 1 This sensor detects the engine speed and performs cylinder identification.
        Cam Position Sensor (Rotor Teeth)

        MRE (Magnetic Resistance Element)

        Type (3)

        		 1 This sensor performs cylinder identification.
        Knock Control Sensor

        Built-in Piezoelectric Element Type

        (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.
        Mass Air Flow Meter Hot-wire Type 1 This sensor uses a built-in hot-wire to directly detect the intake air mass.
        Throttle Position Sensor Non-contact Type 1 This sensor detects the throttle valve opening angle.
        Oxygen Sensor Cup Type with Heater 1 This sensor detects the oxygen concentration in the exhaust emission by measuring the electromotive force which is generated in the sensor itself.
        Air Fuel Ratio Sensor Planar Type with Heater 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 emission linearly.
        Fuel Injector 12-hole Type 4 The fuel injector is an electromagnetically-operated solenoid with a nozzle which injects fuel in accordance with signals from the ECM.
        E.F.I. Engine Coolant Temperature Sensor Thermistor Type 1 This sensor detects the water temperature by means of an internal thermistor.

  2. SYSTEM CONTROL


    1. System Control Table


      1. The engine control system of the 2ZR-FXE engine has the following systems.

        Components Function

        SFI

        (Sequential Multiport Fuel Injection)

        • An L-type SFI system is used, the intake air mass is detected with a hot-wire type air flow meter.

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

        ESA

        (Electronic Spark Advance)

        • The ECM determines the optimal ignition timing in accordance with the signals received from the sensors and sends (IGT) ignition signal to the igniter.

        • The ECM corrects ignition timing in response to engine knocking.

        ETCS-i

        (Electronic Throttle Control System-intelligent)

        		 Optimally controls the throttle valve opening in accordance with the amount of accelerator pedal effort and the conditions of the engine and the vehicle.

        VVT-i

        (Variable Valve Timing-intelligent)

        		 Controls the intake camshaft to an optimal valve timing in accordance with the engine condition.
        Cooling Fan Control Cooling fan operation is controlled by signals from the ECM based on the engine coolant temperature, inverter water temperature, and the air conditioning operating condition.
        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 the SRS airbags deploy.
        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.
        Engine Immobiliser Prohibits fuel delivery, ignition and starting the THS II if an attempt is made to start the THS II with an invalid key.

    2. VVT-i (Variable Valve Timing-intelligent) System


      1. The VVT-i system is designed to control the intake camshaft within a range of 41° (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.

        A01J87ZE01
        A01J7XPE01

    3. Cooling Fan Control


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

    4. Water Pump Control


      1. The ECM regulates the amount of circulating engine coolant to be appropriate to the engine operating conditions based 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.

    5. Fuel Pump Control


      1. A fuel cut function is used to stop the pump once when any of the SRS airbags have deployed. When the power management control ECU detects the airbag deployment signal from the airbag ECU assembly, it transmits an engine off signal to the ECM. Upon receiving this signal, the ECM turns off the circuit opening relay.

  3. CONSTRUCTION


    1. ECM


      1. The ECM is installed in the engine compartment. As a result, the wiring harness has been shortened, thus realizing weight reduction.

        A01J80HE01
        Text in Illustration
        *1 ECM - -

    2. Crank Position and Cam Position Sensors


      1. A pick-up coil type crank position sensor is used. 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.

      2. MRE (Magnetic Resistance Element) type cam position sensor is used. To detect the camshaft position, a timing rotor that is secured to the camshaft is used to generate 3 (3 high output, 3 low output) pulses for every 2 revolutions of the crankshaft.

        A01J86DE01
        Text in Illustration
        *1 Crank Position Sensor *2 Crankshaft Timing Sprocket
        *3 Cam Position Sensor *4 Timing Rotor
        A01J7TFE01

      3. The MRE type sensor consists of a magnet and a sensor with a built-in MRE. 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 either high or low. The ECM detects cam position based on this output voltage.

      4. The differences between an MRE type sensor and a conventional pick-up coil type sensor are as follows

        Sensor Type MRE Pick-up Coil
        Signal Output Constant digital output starts from low engine speeds Analog output changes with the engine speed
        Crank Position and Cam Position Detection

        • Detected by comparing the NE signals with the switching of the high/low output that results from the protruding and non-protruding portions of the timing rotor.

        • Can also be detected based on the number of NE signals input during high/low outputs.

        		 Detected by comparing the NE signals with the change of waveform that is output when the protruding portion of the timing rotor passes.
        A01J7UNE01

    3. 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 advance or retard side. When the engine is stopped, the camshaft timing oil control valve assembly is in the most retarded position.

        A01J7X7E01
        Text in Illustration
        *1 Spring *2 Sleeve
        *3 Spool Valve *4 To Intake VVT-i Controller (Advance Side)
        *5 To Intake VVT-i Controller (Retard Side) *6 Drain
        *7 Oil Pressure - -

    4. 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.

      2. 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.

      3. 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.

        A01J88LE02

      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 a piezoelectric element.

      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.

      7. An open/short circuit detection resistor is integrated in the sensor. When the power 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 IC (Integrated Circuit) 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 DTC (Diagnostic Trouble Code).

        A01J7Q5E01
        Text in Illustration
        *1 Steel Weight *2 Insulator
        *3 Piezoelectric Element *4 Open Circuit Detection Resistor
        *5 Vibration Plate - -
        *a Flat Type Knock Control Sensor (Non-resonant Type) *b Conventional Type Knock Control Sensor (Resonant Type)
        A01J7Z9E01

    5. Mass Air Flow Meter


      1. This compact and lightweight plug-in type air flow meter 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 has been reduced.

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

        A01J7Q0E01
        Text in Illustration
        *1 Hot-wire Element *2 Temperature Sensing Element
        *3 Intake Air Temperature Sensor - -
        *a Air Flow - -

    6. Throttle Position Sensor


      1. The throttle position sensor is mounted on the throttle body to detect the opening angle of the throttle valve. The throttle position sensor converts the magnetic flux density that changes when the magnetic yoke (located on the same axis as the throttle shaft) rotates around the Hall IC into electric signals to operate the throttle control motor.

        A01J7ZKE01
        Text in Illustration
        *1 Throttle Control Motor *2 Throttle Position Sensor
        *3 Throttle Valve *4 Return Spring
        A01J7Q7E01

    7. Oxygen Sensor and Air Fuel Ratio Sensor


      1. The oxygen sensor and the air fuel ratio sensor differ in output characteristics.

      2. The output voltage of the oxygen sensor changes in accordance with the oxygen concentration in the exhaust gas. The ECM uses this output voltage to determine whether the present air fuel ratio is richer or leaner than the stoichiometric air fuel ratio.

      3. Approximately 0.4V is constantly applied to the air fuel ratio sensor, which outputs an amperage that varies in accordance with the oxygen concentration in the exhaust gas. The ECM converts the changes in the output amperage into voltage in order to linearly detect the present air fuel ratio.

        A01J884E01

      4. 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 that are used.

      5. The cup type sensor contains a sensor element that surrounds a heater.

      6. The planar type sensor uses alumina, which excels in heat conductivity and insulation, to integrate a sensor element with a heater, thus improving the warm up performance of the sensor.

        A01J7Z7E01
        Text in Illustration
        *1 Diffusion Resistance Layer *2 Atmosphere
        *3 Heater *4 Platinum Electrode
        *5 Alumina *6 Sensor Element (Zirconia)
        *7 Air Fuel Ratio Sensor (Planar Type) *8 Oxygen Sensor (Cup Type)

    8. Ignition Coil Assembly


      1. An igniter is integrated with the ignition coils, which are provided independently in each cylinder. This improves ignition timing accuracy, reduces high-voltage loss and enhances the overall reliability of the ignition system by eliminating the distributor.

      2. The spark plug caps, which provide contact to spark plugs, are integrated with an ignition coil. Also, an igniter is enclosed to simplify the system.

        A01J89DE02
        Text in Illustration
        *1 Igniter *2 Iron Core
        *3 Spark Plug Cap *4 Secondary Coil
        *5 Primary Coil - -

    9. Spark Plug


      1. Long-reach, thin-electrode type iridium tipped spark plugs are used. This type of spark plug allows the area of the cylinder head which 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 improve ignition performance while maintaining the same durability as platinum-tipped spark plugs.

        A01J7R6E02
        Text in Illustration
        *1 Iridium Tip *2 Platinum Tip
        *3 Water Jacket *4 Cylinder Head Cross Section

  4. OPERATION


    1. VVT-i (Variable Valve Timing-intelligent) System


      1. Using the engine speed, intake air mass, throttle position and water temperature, the ECM can calculate optimal valve timing for each driving condition and controls the cam timing oil control valve. 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.

        A01J7VDE05

      2. When the camshaft timing oil control valve is operated as illustrated below by the advance signal 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.

        A01J7SIE01

      3. When the camshaft timing oil control valve is operated as illustrated below by the retard signal 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.

        A01J80ZE01

      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. Cooling Fan Control


      1. The ECM controls the cooling fan speed based on air conditioning pressure sensor signal, inverter water temperature signal and engine coolant temperature sensor signals.

      2. This control is accomplished by operating the 2 fan motors in 2 stages at low speed (series connection) and high speed (parallel connection).

        A01J824E04
        Air Conditioning Operating Condition

        Engine Coolant Temp.

        Inverter Water Temp.

        		 Relay Operation Cooling Fan Motor Connection Cooling Fan Operation
        No. 1 No. 2 No. 3
        OFF Low Low OFF OFF OFF OFF OFF
        High Low ON ON ON Parallel High
        High High
        A/C Pressure "Low" Low Low OFF OFF ON Series Low
        A/C Pressure "Low" High Low ON ON ON Parallel High
        High High
        A/C Pressure "High" High Low ON ON ON Parallel High
        High High

    3. Water Pump Control


      1. Since this engine is stopped and restarted repeatedly by the hybrid system, by providing an electric type 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 pump motor speed pulse signals from the engine water pump assembly driver circuit, and then determines the pump motor speed so that an optimal engine coolant flow volume can be obtained according to the operating conditions.

        A01J873E05

    4. Fuel Pump Control


      1. a fuel cut function is used to stop the fuel pump once when any of the SRS airbags have deployed. When the power management control ECU detects the airbag deployment signal from the airbag ECU assembly, it transmits an engine off signal to the ECM. Upon receiving this signal, the ECM turns off the circuit opening relay.

      2. After the fuel cut function has been activated, turning the power switch from OFF to ON cancels the fuel cut function, and the engine can be restarted.

        A01J7W1E04

  5. FAIL-SAFE


    1. When the ECM detects a malfunction, the ECM stops or controls the engine according to the data already stored in the memory. For details, refer to the Repair Manual.

  6. DIAGNOSIS


    1. When the ECM detects a malfunction, the ECM diagnoses and memorizes the failed section. For details, refer to the Repair Manual.