What is the reason for the unstable idle speed after replacing the spark plug?

The reason why the idle speed is unstable after replacing the spark plug is that the spark plug itself is abnormal or the throttle valve is too dirty, which leads to inaccurate intake. The following is a detailed introduction about spark plugs of automobiles: 1. Overview: The spark plug of the automobile, commonly known as the burner, uses the pulse high-voltage discharge from the high-voltage line (burner line) to break through the air between the two poles of the spark plug to generate an electric spark to ignite the mixture in the cylinder. It can be roughly divided into standard spark plugs and insulator protruding spark plugs. 2. Others: The basic conditions of high-performance engine are high-energy and stable spark, evenly mixed gas mixture and high compression ratio. The key component of spark plug is insulator. The insulator of spark plug must have good mechanical properties, high pressure resistance, high temperature impact resistance and chemical corrosion resistance. Ordinary spark plugs are mostly made of alumina-based ceramics.