leerlaufregelung

Leerlaufregelung, also known as idle speed control, is a system in internal combustion engines designed to maintain a consistent engine speed when the engine is operating at idle. This idle speed is the lowest speed at which the engine can run smoothly without stalling. The primary function of the leerlaufregelung is to compensate for variations in engine load, such as those caused by the air conditioning system, power steering pump, or alternator.

When these accessories are engaged, they place an additional load on the engine, which would normally cause the engine speed to drop. The leerlaufregelung detects this drop and automatically adjusts the amount of air or fuel entering the engine to counteract the load and bring the engine speed back to its set idle point. This ensures smooth engine operation, prevents stalling, and minimizes fuel consumption and emissions at idle.

Modern leerlaufregelung systems are typically electronic and integrated into the engine control unit (ECU). They utilize sensors to monitor engine speed, throttle position, and various load factors. Based on this information, the ECU commands an actuator, often an idle air control valve or an electronic throttle body, to regulate the airflow to the engine, thereby controlling the idle speed. Older systems might have used vacuum-actuated or mechanical governors, but these are largely obsolete in contemporary vehicles. The precise control offered by electronic leerlaufregelung contributes significantly to overall engine efficiency and drivability.