SFI SYSTEM


  1. FUNCTION


    1. The Dual Variable Valve Timing-intelligent (VVT-i) system is designed to control the intake and exhaust camshafts within a range of 30° and 25° 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.

      A018GH9C02
      *1 Camshaft Timing Oil Control Valve Assembly (Intake) *2 Camshaft Timing Oil Control Valve Assembly (Exhaust)
      *3 Camshaft Position Sensor (Intake) *4 Camshaft Position Sensor (Exhaust)
      *5 Engine Coolant Temperature Sensor *6 ECM
      *7 Crank Position Sensor *8 Intake Mass Air Flow Meter Sub-assembly
      *9 Throttle Position Sensor - -

    2. The dual VVT-i system delivers excellent benefits in the different operating conditions as shown in the table below.


      1. During Idling

        A018GQQE01
        *1 Earliest Timing (EX)
        *2 TDC
        *3 Latest Timing (IN)
        *4 BDC
        Objective Effect
        Eliminating overlap reduces blow back to the intake side.

        • Stabilized idle speed

        • Better fuel economy

      2. At Light Load

        A018GA4E01
        *1 To Advance Side (EX)
        *2 TDC
        *3 To Retard Side (IN)
        *4 BDC
        Objective Effect
        Eliminating overlap reduces blow back to the intake side. Ensured engine stability

      3. At Medium Load

        A018GMYE01
        *1 To Advance Side (IN)
        *2 TDC
        *3 To Retard Side (EX)
        *4 BDC
        Objective Effect
        Increasing overlap increases internal EGR to reduce pumping losses.

        • Better fuel economy

        • Improved emission control

      4. In Low to Medium Speed Range with Heavy Load

        A018GRJE01
        *1 TDC
        *2 To Retard Side (EX)
        *3 To Advance Side (IN)
        *4 BDC
        Objective Effect
        Advancing the intake valve closing timing improves volumetric efficiency. Improved torque in low to medium speed range

      5. In High Speed Range with Heavy Load

        A018G7BE01
        *1 TDC
        *2 To Retard Side (IN)
        *3 To Advance Side (EX)
        *4 BDC
        Objective Effect
        Retarding the intake valve closing timing improves volumetric efficiency. Improved output

      6. At Low Temperatures

        A018GRKE01
        *1 TDC
        *2 Earliest Timing (EX)
        *3 Latest Timing (IN)
        *4 BDC
        Objective Effect
        Eliminating overlap reduces blow back to the intake side to stabilize the idle speed during fast idle.

        • Stabilized fast idle speed

        • Better fuel economy

      7. Starting the Engine/Stopping the Engine

        A018GRKE02
        *1 TDC
        *2 Earliest Timing (EX)
        *3 Latest Timing (IN)
        *4 BDC
        Objective Effect
        Eliminating overlap reduces blow back to the intake side. Improved startability