Why should gasoline engines directly control air intake and fuel injection? Why are there throttles and turbochargers?

Because gasoline is ignited by a spark plug, if the fuel injection quantity is controlled, the fuel injection quantity is too small and the mixing concentration is too low, the spark plug will not burn. For example, if your gas leak encounters sparks, some will explode and some will not. This is the concentration problem, while diesel vehicles are compression-ignition type, which forcibly compresses the air and raises the temperature. At this time, no matter how much diesel oil is injected, it will be ignited, because the temperature and oxygen required for combustion are reached, just like adding fuel to the fire. Turbocharging is not directly related to throttle. Diesel vehicles still have turbocharging without throttle. Turbocharging is to increase the intake air. With the increase of air intake, fuel injection and power, this is the reason why turbocharging with the same displacement consumes oil.