Why does the car suddenly have unstable idle speed and stall?
3 Answers
The reasons for sudden unstable idle speed and stalling are: 1. Throttle blockage, carbon buildup, or abnormal opening; 2. Carbon buildup or blockage in the fuel injector; 3. Spark plug burning or damage; 4. Use of low-quality gasoline leading to fuel pump blockage; 5. Insufficient combustion of the air-fuel mixture in the cylinder. Idle speed is an operating condition of a car, referring to the engine running in neutral gear, which is divided into: 1. Normal idle speed; 2. Driving idle speed; 3. Unstable idle speed. The solutions for sudden unstable idle speed and stalling are: 1. Regularly clean the throttle; 2. Regularly clean the fuel injector to prevent carbon buildup; 3. Replace the spark plug; 4. Use gasoline from reputable gas stations.
I've been driving for over a decade and have encountered several instances where the idle suddenly became unstable and the engine stalled, which was quite annoying. The most common cause is excessive carbon buildup in the throttle body, which blocks the air intake channel. When air doesn't flow evenly, the engine can't 'breathe' properly. If the spark plugs are worn or the gap is incorrect, ignition becomes unstable, especially during cold starts, making stalling more likely. Dirty fuel injectors affecting fuel supply can also cause idle fluctuations. Leaks in the vacuum lines or a clogged air filter are also common culprits, as they disrupt the air-fuel mixture ratio beyond the ECU's control. Once, my car stalled at a traffic light, and upon inspection, a small crack was found in the vacuum line. The solution isn't difficult—regular maintenance, cleaning the throttle body, and replacing spark plugs can usually prevent these issues. However, if you encounter similar problems, don't push through it. Pull over safely, turn on your hazard lights, and address the issue to avoid compromising safety.
I'm a young person who drives to work every day, and recently my car had an unstable idle and stalled at a red light, which was quite scary. Possible causes include issues with the fuel system, such as insufficient fuel pump pressure, clogged fuel injectors, or a dirty fuel filter affecting fuel supply. It could also be a sensor problem, like a dirty mass airflow sensor providing inaccurate data, leading to incorrect computer adjustments. Carbon buildup in the intake manifold can also obstruct airflow. At the time, my car stalled twice in a row, so I immediately went to the repair shop. They cleaned the throttle body, and it worked fine afterward. The cost was just a few hundred yuan. Another potential factor is a partially failed ignition coil, causing poor performance in a single cylinder. A reminder to everyone: keep a warning triangle in your car. In case of emergencies, don’t panic—slow down and pull over safely. Safety first. For prevention, using high-quality gasoline can help reduce carbon buildup.
