The ignition system’s job is to ignite the air-fuel mixture in a gasoline engine. In addition to the spark plugs that spark in the combustion chambers, the ignition system consists of an ignition coil, which converts battery voltage to higher voltage, and the spark plug wires that join these components. Advancements have greatly reduced the need for ignition system service. Where distributor caps and rotors once needed replacement, electronic ignitions typically keep on firing. In new vehicles, spark-plug replacement intervals are often around 100,000 miles. Spark plug wires still require attention and occasional replacement, though an individual coil-on-plug eliminates those wires entirely.
