What potential issue arises if an engine runs too lean?

When an engine runs too lean, this means that there is insufficient fuel compared to the amount of air entering the engine for combustion. A lean air-fuel mixture can lead to increased operating temperatures within the combustion chamber. The reason for this is that a lack of fuel can cause the engine to work harder and generate more heat, as the combustion process becomes less efficient.

As temperatures rise, there is a risk of severe damage to engine components. For example, the pistons, cylinder heads, and valves may overheat and warp, and if the temperatures exceed what the engine materials can withstand, this can result in engine knocking or pre-ignition. This kind of thermal overload can compromise engine longevity, leading to costly repairs or even engine failure if not addressed promptly.

In contrast, while choices related to decreased fuel efficiency, reduced power output, or excessive exhaust emissions can also occur in various situations, the most critical and immediate concern with a lean condition is the potential for increased engine temperatures and associated damage. This underscores the importance of maintaining the correct air-fuel mixture to ensure optimal engine performance and durability.