What should I do if the idle speed of Corolla is sometimes unstable?

Preliminary judgment is the phenomenon caused by excessive carbon deposition. Engine idle jitter is divided into 1, and the engine speed is too low, which leads to vehicle jitter. Maybe the throttle is dirty and needs cleaning. 2. Engine vibration caused by poor engine work, inaccurate fuel injection caused by impurities at the fuel nozzle, and metal oxides such as iron oxide formed on the surface of the spark plug caused by metal additives in fuel will all affect the working condition of the engine. 3. When there is too much carbon in the spark plug, the spark plug will not work and the engine will shake. Cleaning the throttle valve is mainly aimed at the unstable idle speed of the engine and easy flameout. It is recommended that you clean and replace according to the above contents. At the same time, due to many factors that affect the poor working of the engine, it is recommended that you check it as early as 4 s.