How does an excessively lean mixture affect engine performance?

An excessively lean mixture, which occurs when there is too much air in relation to the amount of fuel, can lead to backfiring in an engine. This happens because the lean mixture can ignite too early in the combustion process, or it may not burn completely within the combustion chamber. When unburned fuel exits the combustion chamber and enters the exhaust system, it can ignite due to the heat present there, causing a backfire.

This situation not only affects engine performance negatively, but it can also lead to other issues, such as engine overheating or increased stress on engine components. Understanding the dynamics of fuel-air mixtures is crucial for maintaining optimal engine performance, as the right balance is necessary for efficient and effective combustion.