Sprinter 3500 L5-2.7L DSL Turbo (2004)
Injector opens fully
The control plunger reaches its upper stop where it remains supported by a cushion of fuel which is generated by the flow of fuel between the bleed and
feed orifices. The injector nozzle has now opened fully, and the fuel is injected into the combustion chamber at a pressure almost equal to that in the fuel
rail.
Injector closes (end of injection)
As soon as the solenoid valve is no longer triggered, the valve spring forces the armature downwards and the ball closes the bleed orifice. The armature
is a 2-piece design. Here, although the armature plate is guided by a driver shoulder in its downward movement, it can "overspring" with the return
spring so that it exerts no downwards- acting forces on the armature and the ball. The closing of the bleed orifice lead to pressure build up in the control
chamber via the input from the feed orifice. This pressure is the same as that in the rail and exerts an increased force on the control plunger through its
end face. This force, together with that of the spring, now exceeds the force exerted by the chamber volume and the nozzle needle closes. Injection
ceases as soon as the nozzle needle comes up against its bottom stop again.
