What are the reasons for the engine stalling after prolonged idling?
2 Answers
Here are the reasons for the engine stalling after prolonged idling: Idle stalling: After the engine starts, it runs well from low to high speeds, but stalls immediately when the accelerator pedal is released; or it first runs unsteadily and then stalls. This phenomenon can be identified as an idle stalling fault. Unstable idle: The engine runs unsteadily at idle, and the exhaust pipe makes a "gurgling" sound, which is generally unstable idle. Stabilize the engine at a certain speed and listen for any air leaks. High idle speed: When the engine idles at a speed higher than the normal range and cannot be reduced by adjustment, this is a high idle speed fault. When the engine idle speed is too high, the car should be parked on a flat surface, and the choke knob and hand accelerator knob should be pushed to the bottom for inspection.
As a veteran driver with nearly 20 years of experience, I've encountered idle stalling several times. The most common cause is severe carbon buildup in the throttle body - when sticky deposits jam the valve plate and block airflow, the engine just chokes out. Older cars' idle control valves are particularly prone to failure too; either the spring gets stuck or the motor burns out, making idle unstable. Worn spark plugs with enlarged electrode gaps can't generate enough ignition energy at idle to burn the mixture properly. The most troublesome issue is a clogged fuel pump filter - insufficient fuel supply at low speeds causes sudden fuel cutoff, requiring tank removal to replace the pump core. Last time my car stalled, it was due to a faulty oxygen sensor - the ECU misjudged the air-fuel ratio and kept cutting fuel until it inevitably died at idle. Never force-drive in such situations - getting the trouble codes checked at a repair shop is the smartest approach.
