What is the consequence of a faulty ignition system?

A faulty ignition system can lead to frequent engine misfires and hard starting, which is why this answer is the correct choice. When the ignition system is not functioning properly, it may fail to produce a spark at the right time or may not produce a spark at all. This can result in incomplete combustion of the air-fuel mixture in the engine cylinders, leading to misfires, where one or more cylinders do not fire as intended. This not only affects engine performance but can also make starting the engine difficult.

Additionally, frequent misfires can lead to poor fuel efficiency since the engine is not operating at optimum conditions. Hard starting occurs because the engine may struggle to ignite the fuel mixture adequately, leading to a frustrating experience when trying to start the vehicle.

In contrast, the other options present outcomes that do not align with the reality of a faulty ignition system. Improved fuel economy and power, lower emissions and smooth operation, and increased engine temperature are not typical consequences of ignition system failure. Instead, they signify optimal or healthy engine performance, which is compromised when the ignition system is malfunctioning.