In TDI® engines equipped with the common rail system, all cylinders are located on a single high-pressure rail. In this high-pressure rail, constant pressure is generated, fuel stored and fed to the injectors. The injection rate and point of injection are controlled either via solenoid valves on the individual injectors or via piezo injectors together with the engine management. Systems with solenoid valves have a maximum injection pressure of 1,350 bar; this increases to up to 1,600 bar if piezo injectors are used.