Why does the car idle shake and the engine fault light come on?
2 Answers
Car idle shaking and engine fault light coming on are caused by severe engine carbon deposits, dirty throttle, spark plug failure, poor combustion of engine mixture, etc. The car may also experience phenomena such as knocking and shaking. If the car's mixture is too lean, it may also exhibit symptoms of weak acceleration. The engine's idle speed can be adjusted by modifying the throttle size, with the normal idle speed typically ranging between 550 to 800 revolutions per minute. Problems with the car's idle speed can lead to unusual engine noises. When the accelerator pedal is released during engine operation, the engine enters an idle state. In this state, the engine only needs to overcome its own resistance to operate, resulting in relatively low fuel consumption. Both excessively high and low idle speeds can lead to driving issues.
When my car idles and shakes like it's dancing, with the engine warning light on, I know there's a problem. Having driven for over 20 years, I've encountered this issue several times. The most likely causes are worn-out spark plugs or faulty ignition coils, leading to cylinder misfires and uneven combustion. Mixture problems are also common, such as a dirty mass airflow sensor or clogged fuel injectors, causing insufficient fuel supply and resulting in shaking. Thick carbon deposits can make idle particularly unstable. When the warning light comes on, it means the onboard computer has detected an error. It's best to use a diagnostic tool to read the trouble codes and identify the cause before making repairs. Don't delay—I once waited too long, and minor shaking turned into severe shaking, even damaging the engine. I recommend regularly replacing spark plugs and performing maintenance to prevent carbon buildup. Fuel additives can also help clean the fuel system. In short, start with simple self-checks, and if that doesn't work, seek professional help.
