What happens to combustion efficiency when there is not enough oxygen present?

When there is inadequate oxygen present during combustion, combustion efficiency decreases. This occurs because optimal combustion requires a specific ratio of fuel to oxygen to produce complete combustion, which results in maximum energy release and minimizes the formation of harmful byproducts. Insufficient oxygen leads to incomplete combustion, which means that not all of the fuel is consumed. This results in lower energy output and higher emissions, such as carbon monoxide and soot, indicating that the combustion process is not operating effectively. In essence, the lack of oxygen disrupts the ideal conditions for combustion, leading to a loss of efficiency.