Posted on 12/19/2025
When an engine idles rough, hunts up and down, or stalls at stoplights, it is easy to assume something big is failing. In many cases, the problem starts with a small, dirty part that most drivers never see: the throttle body. As deposits build up around the throttle plate, airflow at idle changes enough to make the engine feel shaky, even if everything else is healthy. Why the Throttle Body Is So Important at Idle The throttle body controls how much air enters the engine. At higher speeds, the opening is large, and small changes do not matter much. At idle, though, the plate is almost closed, and even a thin ring of carbon around the edge can disturb airflow. Modern engines rely on precise air control during idle and light throttle. The computer expects a certain amount of air at a given throttle angle. When buildup restricts that flow, the computer has to compensate, and it does not always get there smoothly. That is when drivers start to feel surging, shaking, or ... read more