SFI SYSTEM


  1. FUNCTION


    1. The Dual Variable Valve Timing-intelligent (Dual VVT-i) system is designed to control the intake and exhaust camshafts within a range of 38° 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.

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


      1. During Idling

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        Objective Effect
        Eliminating overlap to reduce blowback to the intake side.

        • Stabilized idling speed

        • Better fuel economy

      2. At Light Load

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        Objective Effect
        Decreasing overlap to reduce blowback to the intake side. Ensured engine stability

      3. At Medium Load

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        Objective Effect
        Increasing overlap to increase internal EGR to reduce pumping loss.

        • Better fuel economy

        • Improved emission control

      4. In Low to Medium Speed Range with Heavy Load

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        Objective Effect
        Advancing the intake valve close timing to improve volumetric efficiency. Improved torque in low to medium speed range

      5. In High Speed Range with Heavy Load

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        Objective Effect
        Retarding the intake valve close timing to improve volumetric efficiency. Improved output

      6. At Low Temperatures

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        Objective Effect
        Eliminating overlap to prevent blowback to the intake side leads to the lean burning condition, and stabilize the idling speed at fast idle.

        • Stabilized fast idle speed

        • Better fuel economy

      7. Starting and Stopping Engine

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        Objective Effect
        Eliminating overlap to minimize blowback to the intake side. Improved startability