Variable Induction Control Valve: Description and Operation

The DME control unit activates a vacuum-controlled diaphragm valve which either opens or closes the resonance flap. The resonance flap is closed between 3,000 rpm and 5,500 rpm and at a throttle valve opening angle of > 60°. Due to the ignition sequence, the intake system is alternately supplied by both tanks. Due to the firing order, air indrawn in an alternating manner from both intake system tanks. If resonances occur, the intake frequency of one row of cylinders matches the natural frequency of the pressure vibrations in the respective tank. The natural frequency is determined by the geometry of the intake pipes, the resonance pipe and the tanks. A crucial factor, however, is the total length of the pipe from the actual intake cylinder to the next cylinder being supplied, the distribution into intake and the resonance pipe lengths as well as the depth of the tank in the direction of flow. In the no-current state, the resonance flap is open. As soon as the ignition is switched on, however, it is triggered and closed. If the DME control unit detects that the engine is being started, the resonance flap is opened again.

Shift Points for the Resonance Flap
Resonance flap open from 0 - 3,500 rpm and from 5,520 - 6,640 rpm
Resonance flap closed from 3,500 - 5,520 rpm when the throttle valve is open by more than 60°.