What Causes a Car to Stall When the Throttle is Released?
2 Answers
When a car stalls upon releasing the throttle, there can be multiple causes for this issue. Common reasons include: low fuel pressure, clogged air filter, injector atomization or leakage, improper idle adjustment, faulty spark plugs, and air flow meter malfunction. Below is an introduction to related knowledge: 1. Causes of stalling: Fuel injector dripping or clogging inside the engine, circuit faults, or insufficient fuel injection can prevent the injectors from spraying fuel as instructed by the electronic control unit, leading to either too lean or too rich air-fuel mixture in the engine. This can cause poor performance in individual cylinders, resulting in engine stalling. 2. Engine-related reasons: Another factor to consider is carbon buildup in the throttle body. The throttle body controls the intake of air into the engine. Once air enters, it mixes with gasoline to form a combustible mixture that powers the engine. The throttle body plays a crucial role, acting like a valve to regulate air intake into the engine.
I've been repairing cars for almost thirty years and have encountered countless cases of stalling when releasing the throttle. The main cause is usually an issue with the idle system. Excessive carbon buildup in the throttle body can cause it to stick, preventing air from entering when the throttle is released, causing RPMs to drop suddenly and the engine to stall. Another common problem is a faulty idle air control valve that can't regulate air intake properly, or vacuum leaks leading to unstable airflow. Fuel system problems are also major culprits - insufficient fuel supply from the fuel pump or clogged injectors can cause violent fuel pressure fluctuations when releasing the throttle, resulting in stalling. Faulty sensors like throttle position sensors or mass airflow sensors can make the ECU issue wrong commands. I remember a case two years ago with an old Honda that was immediately fixed by replacing the throttle position sensor. This situation is extremely dangerous - stalling at traffic lights can easily cause rear-end collisions, so it must be addressed promptly. I recommend car owners regularly clean their throttle bodies and inspect idle control valves, rather than waiting until problems occur.
