Charge Air Bypass Valve

Charge air bypass valve






Accelerator depressed
When the turbocharger is working, pressure builds up in the turbocharger delivery pipe, throttle body and intake manifold. As long as the throttle butterfly is open, there is pressure on both sides of the bypass valve diaphragm which is held closed partly by the force of the integral spring and partly by the pressure in the intake manifold.






When the accelerator is released
When the throttle butterfly closes, a vacuum is quickly created in the intake manifold due to combustion while the pressure before the throttle butterfly remains the same.

To prevent pressure pulses occurring in the intake hose (with subsequent jerks), the pressure before the throttle butterfly must be released. The bypass pipe signal line, which is usually connected to the outlet before the throttle butterfly, is connected instead to the outlet after the butterfly.

Because of the vacuum in the intake manifold, a vacuum is also created on the spring side in the bypass valve. The vacuum causes the valve to open and the pressure from the delivery pipe and throttle body escapes into the intake hose.

This connection is active until the pressure before the throttle butterfly has stabilized again. The connection between the signal line and the outlet before the throttle butterfly is then restored.