Posted on 6/27/2025
When your car is at a stoplight or parked with the engine running, you expect the engine to idle smoothly. But if the RPMs are bouncing up and down or the engine feels like it's pulsing or sputtering, there’s a good chance something isn’t working properly. Fluctuating idle speed is a sign of an underlying issue that needs prompt attention. Knowing the causes of irregular idle speed will help you address the problem before it leads to poor performance, reduced fuel economy, or a breakdown. What Is Considered Normal Idling Most modern engines idle between 600 and 1,000 RPMs when warmed up. The exact number can vary depending on the engine type and whether accessories, such as the air conditioning, are in use. While brief dips or rises in idle speed can occur, especially during cold starts or gear changes, consistent or noticeable fluctuations should be investigated. If your vehicle surges, stalls, or constantly shifts RPMs while idling, there’s ... read more