What Are the Reasons for a Spark Plug Not Firing?

[JackDella]

Improper adjustment of the spark plug gap, oil accumulation on the spark plug electrode surface, cracks in the spark plug skirt, and carbon buildup on the electrodes can all cause a spark plug not to fire. Below are the diagnostic methods for a spark plug not firing: 1. On-vehicle inspection method: Run the engine at idle speed, use a screwdriver to short-circuit the spark plugs one by one, cutting off the ignition for each cylinder. This can help identify the spark plug that is not firing. Alternatively, remove the spark plug and place it on the cylinder head, then use the end of a tool to contact the spark plug's iron core terminal for a test spark. Observing whether there is a strong spark can help determine the issue. 2. Touch diagnosis: Use your hand to feel whether the insulator is cooler than other spark plugs to determine if it is malfunctioning. Remove the spark plug and observe its surface color, electrode carbon buildup, and technical condition to confirm whether there is a fault.