two-spring injection-nozzle with needle-displacement sensor low fuel injection (the valve needle is lifted against the weak spring # 1) high fuel injection (the valve needle is lifted against stiff spring # 2) the needle-displacement sensor senses start of injection description ordernumber 291 see also: common rail high-pressure pump (DELPHI) Common Rail Piezo-injector one-vane vacuum pump exhaust gas recirculation / EGR