SFI SYSTEM DETAILS VVT-i CONTROL

  1. OPERATION

    1. Based on the engine speed signal, vehicle speed signal, and the signals from the vacuum sensor assembly, throttle position sensor and engine coolant temperature sensor, the ECM can calculate optimal valve timing for each driving condition and controls the camshaft timing oil control valve assemblies. Additionally, the ECM uses signals from the camshaft position sensors and the crank position sensor to detect the actual valve timing, thus providing feedback control to achieve the target valve timing.

      W104581E10

    2. When the camshaft timing oil control valve assembly is operated as shown in the illustration 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.

      Figure 1. Intake Side
      W100540C02

      *1

      Vane

      -

      -

      *a

      Oil Pressure

      *b

      IN

      *c

      Drain

      *d

      Rotation Direction

      *e

      From ECM

      -

      -
      Figure 2. Exhaust Side
      W139425C01

      *1

      Vane

      -

      -

      *a

      Rotational Direction

      *b

      In

      *c

      Drain

      *d

      Oil Pressure

      *e

      from ECM

      -

      -

    3. When the camshaft timing oil control valve assembly is operated as shown in the illustration 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.

      Figure 3. Intake Side
      W100541C02

      *1

      Vane

      -

      -

      *a

      Oil Pressure

      *b

      Drain

      *c

      IN

      *d

      Rotation Direction

      *e

      From ECM

      -

      -
      Figure 4. Exhaust Side
      W139426C01

      *1

      Vane

      -

      -

      *a

      Rotational Direction

      *b

      Drain

      *c

      In

      *d

      Oil Pressure

      *e

      from ECM

      -

      -

    4. After reaching the target timing, the engine valve timing is maintained by keeping the camshaft timing oil control valve assembly 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 camshaft timing oil control valve assembly when unnecessary.