What Causes a Car to Stall Automatically When Waiting at a Stop?
2 Answers
There are several reasons why a car may stall automatically when waiting at a stop: 1. Misoperation: Especially for beginners, incorrect gear shifting, pressing the brake too hard, issues with clutch and throttle coordination, or accidentally turning off the ignition with the key. Simply restarting the engine should resolve this. 2. Dirty throttle body/idle control valve: This often occurs during idling and is usually accompanied by engine shaking. Lightly pressing the accelerator when restarting can help the engine start. It is recommended to clean the throttle body promptly. 3. Ignition system failure: This includes spark plug issues, faulty ignition coils/modules, or aging spark plug wires. Inspect the relevant components. 4. Throttle body or idle control valve failure: These are critical components of the engine's intake system and are relatively precise parts. Stalling or failure to start due to damage to the throttle assembly or idle control valve is not uncommon.
I've been driving for over a decade and often encounter this situation. The most common issue is excessive engine carbon buildup clogging the throttle body, especially during frequent start-stop cycles in city traffic congestion. Poor fuel quality is another factor - many vehicles now use China VI emission systems, which may trigger shutdowns when encountering substandard gasoline. The auto start-stop function is also noteworthy, as the system will shut off the engine when detecting stopped waiting conditions to save fuel. Additionally, an aging battery with unstable voltage or sensor misjudgment can cause unexpected shutdowns. My suggestion is that if frequent stalling occurs at red lights, first check whether the malfunction indicator light is on, or roll down the window to listen for any abnormal engine sounds during shutdown.
