What Causes an Automatic Transmission Car to Stall at Idle While Waiting at a Red Light?

[Melissa]

Engine auto start-stop function automatically shuts off the engine when the vehicle comes to a temporary stop during driving (such as waiting at a red light). When it's time to move forward again, the system automatically restarts the engine. Below is relevant information: Disadvantages: The initial design purpose of auto start-stop technology was to save fuel. When the auto start-stop function is activated, the engine enters a "dormant" state during brief stops, the pulley stops rotating, and the system minimizes engine idling. Working Principle: The auto start-stop system is an onboard computer-controlled system that automatically starts and stops the engine. This system requires the installation of a starter with auto start-stop capability on the engine.

[EverlyAnn]

Last week I just encountered this situation - when stopped at an intersection, the car suddenly stalled when the light turned green, which was quite embarrassing. After checking at home, I think there might be several common reasons: Too much carbon buildup in the engine can affect idle stability, causing large RPM fluctuations that lead to stalling; Or a dirty throttle body causing poor air intake and insufficient fuel supply from the injection system, especially unstable at low RPM. If the idle air control valve is stuck or too dirty, it loses its ability to regulate RPM. Another point is vacuum hose leaks allowing unmetered air to dilute the air-fuel mixture causing stalling. Worn-out spark plugs failing to ignite is also a factor. A temporary solution is trying to restart the engine, while regular maintenance can prevent this. I plan to take it to the shop for cleaning and a comprehensive inspection for peace of mind.

[VonConnor]

Having driven for over a decade, my car has occasionally stalled at idle in front of traffic lights a few times, each time reminding myself to handle it carefully. The possible reasons could be a fault in the idle control system, such as a dirty control valve or a broken motor; a clogged fuel filter affecting fuel supply, especially at idle; an ECU software error might also cause the engine to shut down unexpectedly. Loose ignition coils or wiring can lead to misfires. It's advised not to panic when it happens, turn on the hazard lights and pull over safely, prioritizing safety first. Preventive measures include cleaning the intake pipe and throttle body every 10,000 kilometers, and using high-quality engine oil to reduce carbon buildup. Learned the lesson early in life, forming good habits is crucial.

[LeJocelyn]

I'm a relatively new driver, and once my car suddenly stalled at a red light, which was really nerve-wracking. Afterward, I figured it might be due to carbon buildup causing unstable idling, or a dirty throttle body restricting air intake; or clogged fuel injectors affecting fuel delivery; or bad spark plugs failing to ignite; or a dying battery with low voltage triggering the stall. New drivers should avoid low-speed, short-distance driving to prevent worsening carbon buildup, and using the AC or multiple electronic devices can make problems more likely. Usually, a system cleaning at the repair shop solves the issue. For a simpler approach, you can first check the dashboard warning lights yourself.

[DelJude]

My car stalled once at a red light during daily commuting. Analysis from multiple angles: Carbon buildup affecting engine balance is the most common cause; throttle body dirt causing RPM to drop too quickly leads to stalling; idle air control valve failure can't maintain stable RPM; fuel pump supply insufficiency causes more issues at low speeds; faulty sensors like MAF mislead the ECU. It could also be aging vacuum line leaks. If it happens, pull the handbrake and shift to N for safe parking. Regular professional cleaning and maintenance are recommended, especially for older vehicles - inspect related systems every six months to prevent potential hazards. Safe driving is paramount.

[SebastianLynn]

As someone who frequently drives long distances, I've encountered this issue several times. It usually boils down to: the idle control valve being stuck due to dust accumulation and unable to regulate speed; uneven fuel supply from clogged fuel injectors; a slight vacuum tube leak causing an overly lean air-fuel mixture; or excessively large spark plug gaps leading to unstable ignition. Poor fuel quality also exacerbates carbon buildup. A cost-effective solution is to use fuel additives to clean carbon deposits or replace parts yourself; for severe cases, check the trouble codes for diagnosis. However, if the problem persists, get it repaired immediately to avoid accidents. Regular maintenance, such as frequently changing filters, can help reduce risks.