What Causes a Lean Air-Fuel Mixture in Cars?

[GraceFitz]

The main causes of a lean air-fuel mixture are insufficient fuel injection, inaccurate detection of intake air volume by various intake sensors leading to inadequate fuel injection, excessive carbon buildup that absorbs fuel, and failure of the oxygen sensor's closed-loop control. Here are some relevant details: 1. The air-fuel mixture in cars refers to the gaseous mixture of atomized automotive fuel and air. When the concentration of fuel in the mixture is significantly lower than the fixed value, this is referred to as a lean air-fuel mixture. 2. When the mixture is too lean, the combustion speed of the fuel decreases, and some of the mixture's combustion occurs as the piston moves toward the bottom dead center. This portion of combustion not only converts less heat into mechanical work but also loses more heat to the cooling water or radiator through the cylinder walls. Therefore, an excessively lean mixture can cause engine overheating and reduced power output. 3. A lean mixture can also result in higher idle speeds, and when accelerating or releasing the throttle, the engine speed may take longer to return to idle speed.