The Air-Fuel Ratio (AFR) is the proportion of air to fuel in an internal combustion engine. It is crucial for efficient engine performance, as the right balance ensures complete combustion, maximizing power and minimizing emissions. A typical AFR for gasoline engines is around 14.7:1, meaning 14.7 parts air to 1 part fuel. Maintaining the correct AFR is essential for optimal engine operation. If the ratio is too rich (more fuel), it can lead to incomplete combustion, resulting in increased emissions and reduced fuel economy. Conversely, a lean mixture (more air) can cause engine knocking and overheating, potentially damaging the engine.