WIS Document: 8512

| | Charge air bypass valve | 1. | Over-pressure in intake manifold | 2. | Throttle plate open | 3. | Charge air bypass valve closed | With depressed accelerator When the turbocharger is operating, an over- pressure is created in the turbo pressure pipe, the throttle body and the intake manifold. As long as the throttle plate is open, there is also an over-pressure on both sides of the charge air bypass valve's diaphragm, which is closed by the force of the built-in spring and the over-pressure from the intake manifold. | With the accelerator disengaged | 1. | Under-pressure in the intake manifold | 2. | Throttle plate closed | 3. | Charge air bypass valve open When the throttle plate is closed, an under-pressure is quickly created in the intake manifold while the over-pressure in front of the throttle plate remains. To avoid a rapid increase in the pressure in the intake manifold when the throttle plate is opened again, which would result in a jerk, the over-pressure in front of the throttle plate must be released. Through the under-pressure in the intake manifold we also obtain an under-pressure on the spring-side of the charge air bypass valve. The spring's force is not enough to enable the valve to resist the over- pressure on the other side of the diaphragm, which means that the valve opens and the over-pressure from the pressure pipe and the throttle body is released into the intake manifold.