SFI SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. System Control Table


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

        Components Outline Quantity Function
        ECM 32-bit CPU 1 The ECM optimally controls the SFI, ESA, EGR and ETCS-i 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.
        Crank Position Sensor (Rotor Teeth) Pick-up Coil Type (36 - 2) 1 This sensor detects the engine speed and crank angle.
        Cam Position Sensor (Rotor Teeth) Pick-up Coil Type (3) 1 This sensor performs cylinder identification and detects camshaft angle.

        • Throttle with Motor Body Assembly


          • Throttle Position Sensor

        		 Non-contact Type 1 This sensor detects the throttle valve opening angle.
        Knock Control Sensor Built-in Piezoelectric Element Type (Flat Type) 1 This sensor detects the occurrence of the engine knocking indirectly from the vibration of the cylinder block caused by the occurrence of engine knocking.
        E.F.I. Engine Coolant Temperature Sensor Thermistor Type 1 This sensor detects the engine coolant temperature by means of an internal thermistor.
        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 emission. However, it detects the oxygen concentration in the exhaust emission linearly.
        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 which is generated in the sensor itself.
        Fuel Injector Assembly 12-hole Type 4 The fuel injector assembly is an electromagnetically-operated solenoid with a nozzle which injects fuel in accordance with signals from the ECM.

  2. SYSTEM CONTROL


    1. System Control Table


      1. The engine control system of the 1NZ-FXE engine has the following systems. The ECM that controls this system is made by DENSO.

        Components Function
        Sequential Multiport Fuel Injection (SFI)

        • 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.

        • 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 camshafts (intake) to an optimal valve timing in accordance with the engine operating conditions.
        Cooling Fan Control Cooling fan operation is controlled by signals from the ECM based on the engine coolant temperature, air conditioning operation conditions and hybrid system coolant temperature.
        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 sensor or oxygen sensor at an appropriate level to increase the ability of the sensors to accurately detect the oxygen concentration.
        Exhaust Gas Recirculation (EGR) Control 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.

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


      1. The VVT-i system is designed to control the camshaft (intake) within a range of 47° (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.

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    3. Cooling Fan Control


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

    4. 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.

    5. Fuel Pump Control


      1. A fuel cut function is used to stop the fuel pump when any of the SRS airbags have deployed. When the hybrid vehicle control ECU detects an 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 C/OPN 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.

    2. Intake Mass Air Flow Meter Sub-assembly


      1. This compact and lightweight plug-in type intake mass air flow meter sub-assembly 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 intake mass air flow meter sub-assembly has a built-in intake air temperature sensor.

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        Text in Illustration
        *1 Platinum Hot-wire Element *2 Temperature Sensing Element
        *3 Intake Air Temperature Sensor - -
        A01UWXO Air Flow - -

    3. Crank Position Sensor and Cam Position Sensor


      1. Pick-up coil type sensors are used for the crank position and cam position sensor.

      2. The timing sprocket of the crankshaft has 34 teeth, with 2 teeth missing. Based on these teeth, the crank position sensor transmits crank position signals (NE signal) consisting of 33 high or low output pulses every 10° per revolution of the crankshaft, and 1 high or low output pulse every 30°. The ECM uses the NE signal for detecting the crank position as well as for detecting the engine speed. It uses the missing teeth signal for determining the top dead center.

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

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        Text in Illustration
        *1 Crank Position Sensor *2 Timing Sprocket
        *3 Cam Position Sensor *4 Timing Rotor
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        Sensor Output Waveforms
        *1 Crank Position Sensor

    4. Throttle Position Sensor


      1. The throttle position sensor is mounted on the throttle with motor body assembly 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.

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        Text in Illustration
        *1 Throttle Valve *2 Throttle Position Sensor
        *3 Throttle Control Motor - -
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    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.

        A flat type knock control sensor (non-resonant type) has the ability to detect vibration in a wider frequency band (from about 5 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.

          *: 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. The engine knocking frequency will vary slightly depending on the engine speed. A flat type knock control sensor can detect vibration even when the engine knocking frequency changes. Due to the use of a 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.

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      3. 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.

      4. 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 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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        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)
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        *1 Flat Type Knock Control Sensor
        *2 Open/Short Circuit Detection Resistor
        *3 Piezoelectric Element

    6. 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 air fuel ratio sensor and oxygen sensor is the same. However, they are divided into the planar type and the cup type, according to the different types of heater construction that are 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.

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

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

      5. As illustrated below, the 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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    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 camshaft timing gear assembly (VVT-i controller) advance or retard side. When the engine is stopped, the camshaft timing oil control valve assembly will move to the retard position.

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        Text in Illustration
        *1 Spring *2 Sleeve
        *3 Spool Valve - -
        *a To camshaft timing gear assembly (Advance Side) *b To camshaft timing gear assembly (Retard Side)
        *c Drain *d Oil Pressure

    8. No. 1 Ignition Coil


      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 a No. 1 ignition coil. Also, an igniter is enclosed to simplify the system.

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

    9. Spark Plug


      1. Iridium-tipped spark plugs improve ignition performance while maintaining the same durability as platinum-tipped spark plugs.

        Type DENSO Made FK16R-A8 (Iridium)
        Plug Gap 0.7 mm to 0.8 mm (0.0276 in. to 0.0315 in.)
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        Text in Illustration
        *1 Iridium Tip *2 Platinum Tip

  4. OPERATION


    1. Variable Valve Timing-intelligent (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 cam position sensor and the crank 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 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.

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      3. When the camshaft timing oil control valve assembly 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.

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      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 driving conditions change. This maintains 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. To achieve an optimal fan speed in accordance with the engine coolant temperature, air conditioning operation conditions and hybrid system coolant temperature, the ECM calculates the proper 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 motor. Also, the fan speed is controlled by the ECUs using the stepless control.

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    3. 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 pump motor speed pulse signals from the electric water pump 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.

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    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 hybrid vehicle 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 C/OPN 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.

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  5. 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.

  6. 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 the Global TechStream (GTS).

    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 GTS or disconnecting the cable from the negative (-) battery terminal.

    4. To clear other DTCs that are stored in the ECM, use the GTS, disconnect the cable from the negative (-) battery terminal, or remove the EFI MAIN fuse and ETCS fuse for 1 minute or longer.

    5. For details, refer to the Repair Manual.