Why does the car automatically shut off when stopping?
3 Answers
The following are the reasons why a car automatically shuts off when stopping: 1. Misoperation: Especially for beginners, such as shifting to the wrong gear, braking too hard, improper clutch-throttle coordination, or accidentally turning off the car with the key. Simply restart the engine. 2. Dirty throttle/idle speed control valve: This mostly occurs at idle speed, often accompanied by engine shaking. Lightly press the accelerator when restarting to provide fuel for ignition. It is recommended to clean the throttle promptly. 3. Fuel system failure: Causes include poor fuel quality, running out of fuel, fuel pump burnout, clogged fuel lines, faulty fuel pump fuse, or defective fuel pressure sensor. Inspect related components. 4. Ignition system failure: Includes spark plug issues, faulty ignition coil/module, or aging cylinder wires. Check related components. 5. Throttle or idle speed control valve failure: These are critical components of the engine intake system and relatively precise parts. Many cases of engine stalling or failure to start are due to damaged throttle assemblies or idle speed control valves.
I've been driving for decades and have seen many cases of automatic engine stalling when parking. There are several main reasons: Fuel supply issues are quite common, such as aging fuel pumps or clogged filters - when fuel can't reach the engine, it naturally stops running. Spark plugs are also critical - when ignition coils age or carbon buildup gets too thick, failure to ignite at idle can easily cause stalling. Then there's dirty intake systems - when the mass airflow sensor gets clogged with sludge and reports wrong data, the ECU sends incorrect commands. I've also encountered stuck idle control valves - that component manages engine speed when parked, and if it jams, the engine stalls immediately. If this happens before a traffic light, it can be quite dangerous - quickly turn on hazard lights and slowly pull over to check. Don't skimp on regular maintenance - periodically replacing spark plugs and cleaning the throttle body can prevent about 70% of such failures.
Last time my car suddenly stalled when stopping at an intersection, which was really embarrassing. After inspection, it turned out the throttle body was severely carbon-fouled, like coated with a layer of sludge, causing insufficient air intake that directly choked the engine. The mechanic said loose battery terminal connections could also cause power interruption, so I went home and tightened all the terminal screws. For automatic transmission models, torque converter pressure leakage could be another factor - when hydraulic power transmission fails, it's like suddenly shifting to neutral. Also, using substandard gasoline can clog fuel injectors, feeling like being choked while running. Sensor issues shouldn't be ignored either - a faulty crankshaft position sensor can make the ECU misjudge engine status and issue shutdown commands. Now I always refuel at authorized gas stations and get the fuel system cleaned every 20,000 km - no more stalling since then.
