Why Does a Car Stall When Coasting in Neutral?

[RosalieAnn]

Issues with the throttle valve and idle speed. Below are the relevant explanations: Causes: It may be caused by excessive carbon buildup in components such as the throttle body, idle air control valve, intake valves, intake manifold, combustion chamber, spark plugs, and fuel injectors. Symptoms: This carbon buildup can block the idle passage, causing the idle air control valve to stick or exceed its adjustment range. This can result in low idle speed, unstable idle, or even engine stalling when releasing the throttle. Additionally, it is important to check if the fuel injectors are leaking, which would cause them to continue supplying fuel even after the throttle is released. This leads to an overly rich air-fuel mixture at low speeds, resulting in unstable idle or, in severe cases, engine stalling. Recommendations: Low idle speed or poor fuel delivery can cause the car to stall when coasting in neutral. Coasting in neutral is not recommended. Due to the high inertia when going downhill, it becomes difficult to handle emergencies. If the engine stalls, the vehicle becomes uncontrollable, increasing the risk of accidents.