What is the difference between port fuel injection and direct fuel injection?

The distinction between port fuel injection and direct fuel injection is fundamentally linked to where the fuel is introduced into the engine's air-fuel mixture. In port fuel injection, the fuel is injected into the intake manifold, where it mixes with the incoming air before entering the combustion chamber. This method allows for better fuel atomization and a homogenized air-fuel mixture, which can enhance combustion efficiency and performance.

On the other hand, direct fuel injection involves injecting fuel directly into the combustion chamber at high pressure. This approach allows for better control of the fuel delivery, improving combustion efficiency and reducing emissions. Direct injection is known for providing better power output and efficiency, particularly under high-load conditions.

The reasoning behind the correct answer emphasizes the key functional difference in the injection point between the two systems, which has direct implications for engine performance, emissions, and efficiency.