SFI SYSTEM


  1. OPERATION


    1. A Swirl Control Valve (SCV) is used for each cylinder. Each cylinder has 2 independent intake ports, 1 for each intake valve. The SCV is able to open or close one of these ports. The opening and closing of the swirl control valves is controlled by the ECM.

    2. The SCVs for the left and right bank intake ports are connected by a link mechanism. They are activated by a single SCV actuator (compact DC motor).

    3. The ECM activates the SCV actuator to open or close the SCVs based on engine speed, engine coolant temperature and driving conditions.

    4. Closing one of the ports accelerates the speed of the intake air that flows through the other port, strengthening the turbulence in the combustion chamber. This results in enhanced atomization of fuel when the coolant temperature is low, thus stabilizing combustion.

    5. When the engine is operating at low speed and low load conditions, the SCV remains fully closed. Thus, only one port is used for intake, in order to promote the mixture of air and fuel. This also accelerates the intake flow speed, which enhances combustion and fuel economy.

    6. When the engine is operating at high load conditions, the SCV opens to allow the intake of air to each cylinder through both ports. This increases the intake air volume and enhances charging efficiency. At the same time, this creates a vertical swirl current (tumble current) in the combustion chamber to promote the mixture of air and fuel, thus improving performance.

      A0120L0C02
      *A Models with SCV Position Sensor - -
      *1 Exhaust Valve *2 Intake Valve
      *3 Intake Manifold *4 Swirl Control Valve
      *5 Intake Air Surge Tank Assembly *6 SCV Position Sensor
      *7 SCV Actuator (DC Motor) *8 Link Mechanism
      *a Intake Port Image *b Intake Port Division Continues
      *c Division of Intake Port Starts *d Flow of Air with Swirl Control Valve Open
      *e Flow of Air with Swirl Control Valve Closed - -