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Charge air bypass valve

Charge air bypass valve



1. Overpressure in the intake manifold

2. Throttle valve open

3. Charge air bypass valve closed


With 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 is open, there will be pressure on both sides of the bypass valve diaphragm, which is kept closed partly by the force of the integrated spring, partly by the pressure from the intake manifold.

With accelerator released



1. Vacuum in the intake manifold

2. Throttle valve closed

3. Charge air bypass valve open


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

The positive pressure ahead of the throttle disc must be released in order to prevent pressure thrust resulting in jerkiness once the throttle disc is reopened. The bypass valve signal line, which is connected to the outlet ahead of the throttle disc during normal driving, will then instead be connected to the outlet after the throttle disc by a solenoid valve controlled by Trionic. For more information, see Bypass control valve .

The vacuum in the intake manifold causes a vacuum on the spring side of the bypass valve as well. The vacuum opens the valve and allows the pressure from the delivery pipe and throttle body to evacuate to the inlet hose.

This connection is active until the pressure in front of the throttle is stable again, after which the connection is switched back between the signal line and the outlet in front of the throttle.