tyhjäkäyntikierroksia

Tyhjäkäyntikierros, or idle speed, refers to the rotational speed of an engine when it is running without any load applied, such as when a vehicle is stationary with the transmission in neutral or park. This speed is typically measured in revolutions per minute (RPM). The engine control unit (ECU) in modern vehicles manages the idle speed to ensure smooth operation and efficient fuel consumption.

When an engine idles, it still requires fuel and air to maintain combustion and keep running. The ECU adjusts various parameters, including throttle position, fuel injection timing, and spark plug firing, to maintain a stable idle RPM. This idle speed is crucial for preventing the engine from stalling and for powering auxiliary systems like the air conditioning compressor, power steering pump, and alternator.

Factors influencing idle speed include engine temperature, ambient air temperature, and the electrical load on the system. For instance, when the engine is cold, the idle speed is often set higher to help it warm up more quickly and achieve optimal operating temperature. Similarly, if the air conditioning is turned on, the ECU will typically increase the idle speed slightly to compensate for the extra load placed on the engine. Deviations from the designed idle speed, such as rough idling or excessively high or low RPMs, can indicate underlying mechanical or electronic issues within the engine.