How does changing the air-fuel ratio affect engine performance?

Changing the air-fuel ratio plays a critical role in optimizing engine performance, making this the correct choice. An optimal air-fuel mixture ensures complete combustion, which maximizes the energy extracted from the fuel. When the ratio is balanced, the engine runs more efficiently, promoting better power output, smoother operation, and reduced engine strain. This is crucial for performance as it allows the engine to function effectively across various load conditions.

Excessively rich or lean mixtures can lead to incomplete combustion. A rich mixture may waste fuel and increase emissions, whereas a lean mix could result in engine knocking and potential damage. Hence, maintaining the correct air-fuel ratio is vital for achieving the desired combustion efficiency and overall performance of the engine.