Ignition Coils

What are Ignition Coils?

To ignite the compressed air-fuel mixture in a gasoline engine, powering most of today’s vehicles, a spark is critical. The spark plug is mounted in the cylinder, but ignition coils generate the energy needed to create a spark hot enough to jump the gap and ignite the fuel. Ignition coils are small step-up transformers, ramping up 12 V from the car’s electrical system to near 20,000 V.

To make a spark, the ignition system powers up an individual ignition coil’s primary coil momentarily, creating a powerful magnetic field. When the 12-V primary windings are disconnected, the magnetic field collapses, generating a high voltage spike in the ignition coil’s secondary windings. The secondary windings are connected to the spark plug via high-voltage ignition wires. For just a couple milliseconds, the spark reaches upwards of 5,000 °K (8,500 °F).

Depending on the vehicle, there may be one or more ignition coils. Older distributor ignition system used a single ignition coil for all cylinders. Some older distributor-less ignition systems (DIS) used one ignition coil per cylinder or one per pair of cylinders. Most modern DIS engines use coil-on-plug (COP) ignition coils, one per cylinder, mounted directly on the spark plugs.

Why are Ignition Coils Important?

Ignition coils are critical to the function of the gasoline engine, but their exposure to the heat of the engine causes them to degrade over time. Aged ignition coils may not generate enough voltage for a reliable spark, or a cracked ignition coil may short-circuit, sending spark energy elsewhere. Either way, compromised ignition coils will lead to cylinder misfire problems, hard starting, poor performance and fuel economy, possibly catalytic converter damage. On post-1996 vehicles with OBDII systems, ignition coil problems usually result in the engine control module setting the check engine light and storing diagnostic trouble codes (DTC).

What can Dobbs Tire & Auto Centers Do for You?

Ignition systems are complex and sensitive, but the right tools and training give our ASE-Certified technicians the edge they need to diagnose and repair ignition systems of all kinds. If you are experiencing engine performance problems or your check engine light is on, faulty ignition coils could be at the root of the problem. You can have your vehicle diagnosed by a technician at Dobbs Tire & Auto Centers, at one of 43 locations in the St. Louis area.

“You Can Depend on Dobbs” – Dobbs Tire & Auto Centers, Home of the Fixed Forever Service Warranty. Locally and Family Owned Since 1976