The amount of fuel is calculated by the length of fuel injection time of the fuel injector. The fuel supply computer (ECU) calculates the fuel supply according to the air flow, engine speed, and compensation signals provided by various sensors, using the previously set fuel supply program. The required fuel supply time, this fuel supply program can be expressed in a graphical way. The fuel injection time calculated by ECU is the sum of “basic injection time”, “compensation injection time” and “invalid injection time”, the unit is microsecond (ms), 1ms=0.001 second. The amount of gasoline sprayed by the fuel injector per unit time is determined by the size of the caliber of the fuel injector itself and the size of the fuel injection pressure. Basic injection time The basic injection time is determined by the intake air volume (weight in this case) and the engine speed. When you step on the accelerator pedal, what you control is the opening angle of the throttle valve. The larger the opening, the greater the air intake. After comparing with the specified fuel supply program, calculate the required fuel supply amount and relative injection time.