What defines 'idle speed' in an engine?

Idle speed in an engine is defined as the engine speed without load, measured in RPM. This speed is crucial for ensuring that the engine runs smoothly when not under any operational demand, allowing it to maintain optimal functionality and avoid stalling. At idle speed, the engine is still running and can respond to throttle inputs but is not being subjected to additional stress from a load.

Understanding idle speed is important for engine management systems, as it determines the baseline operating conditions for the engine before any external demands are placed on it. This speed is typically set by the manufacturer and can vary based on engine design and application, ensuring reliable performance during low-power conditions.