What are the causes of engine stalling at idle?
2 Answers
Car engine stalling at idle can be caused by: 1. Damage to the engine idle control valve or its wiring; leakage in the vacuum pipe of the brake vacuum booster; damage to the diaphragm of the brake vacuum booster; air leakage in the intake manifold; issues with the idle control module in the engine's electronic control unit (ECU); 2. Sticking of the engine idle control valve; wear on the insulation of the idle control valve's wiring; clogging of the idle air passage; problems with the engine throttle position sensor; 3. Issues with the camshaft position sensor or crankshaft position sensor; problems or excessive dirt on the engine speed sensor; issues with the idle control program in the engine's electronic control unit, etc.
I often encounter the issue of stalling at idle. As an experienced driver, I find it quite annoying. The most common cause is an underperforming fuel system, such as an aging fuel pump or clogged fuel injectors, which prevents fuel from reaching the engine, making it unable to run smoothly. Additionally, problems with the ignition system are not uncommon—excessive carbon buildup on the spark plugs or a faulty ignition coil can cause misfires at idle, leading directly to stalling. Another culprit could be a dirty throttle body, where carbon deposits block the air intake, resulting in insufficient airflow to maintain stable RPM. Sometimes, the idle control valve malfunctions; it manages speed control when the car is stationary, and if it fails, stalling becomes more likely. A weak battery might also contribute, especially in cold weather when voltage fluctuates after startup. Safety first—if this keeps happening, it's best to get a maintenance check promptly and not wait until it becomes dangerous.
