As the spark plug center electrode wears down, what happens to the voltage required to fire the plug?

As the spark plug center electrode wears down, the voltage required to fire the plug actually increases. This occurs because the wear on the electrode creates a larger gap that the spark must jump over. A larger gap requires a higher voltage to overcome the air gap and produce a sufficient spark for ignition. Therefore, as the condition of the spark plug deteriorates due to wear, the ignition system has to generate more voltage to maintain the same level of performance in igniting the air-fuel mixture in the combustion chamber.

In general, spark plugs are designed to operate within a specific range of voltages, and significant wear can lead to harder starting conditions, misfires, or even poor engine performance. Regular maintenance and timely replacement of spark plugs can help prevent these issues and ensure the ignition system operates effectively.