Which condition leads to a lean mixture in engine combustion?

A lean mixture in engine combustion occurs when there is more air than fuel. This imbalance results in a higher air-to-fuel ratio, meaning that there is insufficient fuel to combust with the available air. When there is too much air, the engine may not achieve optimal power output, and the combustion can be less efficient, leading to higher temperatures and potentially increased emissions.

In combustion processes, the stoichiometric ratio is the optimal fuel to air ratio, where both fuel and air are present in ideal proportions for complete combustion. When this balance is disrupted by adding excess air, the mixture becomes lean.

Other conditions, such as having more fuel than air, indicate a rich mixture which can lead to incomplete combustion. Similarly, a balanced fuel mixture refers to the stoichiometric condition, which is not lean either. Ultimately, the characteristic of having more air than fuel distinctly defines the lean mixture scenario.