What is a common sign of a faulty ignition system?

A common sign of a faulty ignition system is engine missing under load. This phenomenon occurs when the ignition system fails to provide a consistent spark at the correct timing to the engine’s cylinders. When the engine is under load—such as when accelerating or climbing a hill—it requires more power from the ignition system. If there is a malfunction, such as worn spark plugs, a failing ignition coil, or issues with the ignition timing, the engine may not fire properly, leading to a noticeable misfire or hesitation.

When the engine misfires, it can result in a rough running condition, reduced power, and increased emissions. This is especially pronounced under load since the demand on the engine increases, revealing weaknesses in the ignition system more readily than when the engine is idling or cruising at lower speeds. Therefore, recognizing engine missing under load is crucial for diagnosing issues related to the ignition system effectively.