Intake system in FSI engines — general description (Audi A4 B6)

The new Fuel Stratified Injection technology works with a powerful intake system. The volume of oxygen intake is analyzed by a hot-air flow meter. An electronic accelerator pedal controls a water-heated throttle valve. Before the air enters the intake manifold, and depending on the engine operating mode, the return of exhaust gases to the combustion chamber reaches 35 percent. The exhaust gases are taken from the exhaust port of the fourth cylinder.

The newly designed exhaust gas recirculation valve is responsible for regulating this process. By returning the exhaust gases to the combustion chamber, the nitrogen oxide content is significantly reduced immediately after the engine. This effect is supported by variable adjustment of the intake camshaft.

An important component of the intake tract is the new multifunctional module. This module comprises the high-pressure fuel distributor, special rotary flaps, a mechanical or sensor control unit for the separate control of the two FSI-specific phases (layered charge mode and homogeneous mode), as well as a pressure sensor together with a control valve. Without the multifunctional module, neither the pressure of more than 100 bar, which is produced by the fuel injection system with a common fuel rail, nor the transition from the economical stratified charge mode to the homogeneous mode could be realized.