WS3-1

Petrol Injectors:
At the voltage supply the injectors are closed because they havent been earthed out by the ECU yet at the point where we have injector opening the ECU earths out the injector and the solenoide inside is energised to open the injector and the Back EMF is produced as the magnetic field collapses on itself which creates a hight peak ... to keep the injector open only a little bit of energy is needed compare to when they need to be opened . after the injector is closed the voltage goes back to supply voltage till the next time its earthed out by the ECU to be opened and this opening and closing is also known as PWM. which is sent from ECU .