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Solenoid operated gaseous injectors, when compared to conventional liquid fuel diesel injectors, differ in the way the fuel dose and its discharge rate are controlled. While in conventional diesel systems, the fuel dose and its injection rate depends on the fuel injection pump effective stroke and on the plunger diameter and velocity, the solenoid injectors operate in an “on-off” manner which limits the ability to control the gas discharge rate, resulting in its profile to be basically rectangular in shape. To reduce the gas injection rate at the beginning of the injection process in order to suppress the “diesel-knock” phenomenon, similar procedures as used in diesel engines could be implemented. One such approach is to use a throttling type pintle nozzle, and another method is to use a double-spring injector with a hole nozzle.

The existing state of the art in solenoid operated injectors technology promotes their use mainly for gasoline manifold injection in spark ignition engines. The attempts to use such injectors for direct fuel injection are hampered by slower and less repeatable dynamic response, as compared with hydraulically or mechanically operated diesel injectors. Also, the impact of the solenoid overheating and the resulting loss of power, is considered detrimental for such injectors when installed in the cylinder head of an engine. The next (third) generation of solenoid operated injectors is dealing with all these disadvantages. First, it is using a special inductive driving circuit for the solenoid to boost the opening of the injector needle by amplifying the supply voltage, but only for a very short instant of time.