The fuel injector itself is a normally closed valve (normally closed valve means that the valve is always closed when there is no input control signal; while normally open valve means that the valve is always open when there is no input control signal), by A valve needle moves up and down to control the opening and closing of the valve. When the ECU issues a fuel injection command, its voltage signal will cause current to flow through the coil in the fuel injector, generating a magnetic field to attract the valve needle, allowing the valve to open so that fuel can be sprayed out from the fuel injection hole. The biggest advantage of injection fuel supply is that the control of fuel supply is very precise, so that the engine can have the correct air-fuel ratio in any state, not only to keep the engine running smoothly, but also the exhaust gas can meet the environmental protection regulations.