What effect does a faulty spark plug typically have on engine performance?

A faulty spark plug can significantly disrupt the normal functioning of an engine by causing misfiring. This misfiring happens because the spark plug fails to ignite the air-fuel mixture at the appropriate time, leading to incomplete combustion. When this occurs, the engine may experience a loss of power since not all cylinders are firing correctly, which translates to reduced efficiency and performance. Moreover, this lack of proper ignition can create a rough idle and increased emissions, further indicating that the engine is not operating optimally. The presence of misfires can also lead to greater wear and tear on engine components, ultimately resulting in more severe mechanical issues if not addressed.

In contrast, other options do not accurately reflect the impact of a faulty spark plug on engine performance. For example, a malfunctioning spark plug does not enhance engine power or increase fuel efficiency; rather, it adversely affects both. Additionally, a faulty spark plug is unlikely to prevent overheating, as overheating can stem from various other factors not related to spark plug function.