SFI SYSTEM


  1. OPERATION


    1. Using the engine speed, intake air mass, throttle position and engine coolant temperature, the ECM can calculate optimal valve timing for each driving condition and controls the camshaft timing oil control valve. In addition, the ECM uses signals from the camshaft position sensor and the crankshaft position sensor to detect the actual valve timing, thus providing feedback control to achieve the target valve timing.

      A01N5IVE01

    2. When the camshaft timing oil control valve 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:

      A01N5FWC01
      *1 Vane *2 Rotation Direction
      *3 ECM *4 In (Oil Pressure)
      *5 Drain (Oil Pressure) - -
      *a Advance Side Operation Intake Side *b Advance Side Operation Exhaust Side

    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:

      A01N5EYC01
      *1 Rotation Direction *2 Vane
      *3 ECM *4 Drain (Oil Pressure)
      *5 In (Oil Pressure) - -
      *a Retard Side Operation Intake Side *b Retard Side Operation Exhaust Side

    4. After reaching the target timing, the engine valve timing is maintained by keeping the camshaft timing oil control valve in the neutral position unless the engine operating conditions change. This maintains the engine valve timing at the desired target position by preventing the engine oil from running out of the oil control valve.