What is the throttle function of turbocharged direct injection engine?

Dude, you're right. Direct injection is to control the fuel injection quantity. The throttle opening of ordinary intake branch injection vehicle is the main control signal of fuel injection, that is, how much gas is injected, while direct injection is just the opposite. The throttle opening sensor becomes a modified auxiliary signal, the gas can enter at will, and the engine controls the fuel injection quantity. Fuel injection is rich in mixed gas, but fuel injection is poor in mixed gas. This is to achieve lean combustion. If you want to study in-cylinder direct injection, I recommend a book for you, from Phoenix Publishing House.