Ignition Coils

Although the fundamentals of an ignition coil have not changed, the demands placed onthem have. Tighter emissions regulations, less engine space and requirements for better fuel economy and higher ignition voltage – up to 45,000 volts in modern cars - means that coil technology is constantly evolving. As a leading OE manufacturer, Delphi has been at the forefront of many of these changes. With more than 100 years of OE ignition system expertise, we’ve created advanced magnetic design and modelling capabilities that are second to none. The result, an efficient coil design that delivers optimum engine performance, exhaust emissions and fuel economy.

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Optimum wire length

More wire generates differences in voltage, and in turn extra pressure, that can cause the breakdown of insulation and wire coatings. So, we tightly control the length of wire between adjacent primary and secondary windings. The result? Our secondary winding is thinner and much longer than the primary in order to get the output needed for the voltage to jump the spark plug gap.

Smart processes

Ignition coil windings should also be evenly distributed and neatly wrapped. That’s why we wind both primary and secondary coils as smoothly and tightly as possible, directly onto a proprietary steel core. This approach helps to ensure maximum magnetic power in every turn of the wire. We also wind our secondary coils into more bays than many of our competitors for more consistent voltage distribution and reliable coil performance.

High quality components

We only ever use high-quality wires, and coating that resists the cracks, pin holes and imperfections that might cause other ignition coils to fail. A special Epoxy helps insulate these wires and keeps them separated. Gaps in the epoxy can reduce the integrity of the insulation, so we also employ a special vacuum technique to remove air bubbles and imperfections, and help prevent internal arching and shorts.

The Delphi Difference

100 years of OE experience, supplier to the world’s top automakers
OE heritage and knowledge built into every aftermarket part
Comprehensive portfolio for a wide range of vehicles and model years
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Related product resources and downloads

How to test ignition coil | Masters of Motion

Ignition 1 min read

How to test ignition coils

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Ignition Vehicle Electronics & Engine Management How to Technicians 1 min read

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A poorly performing ignition coil could lead to problems with vehicle performance and efficiency. Learn how to test an ignition coil with this Masters Of Motion video guide from our Delphi Technologies expert.

How does the design of ignition coils differ?

The design of an ignition coil can range from 2 to 7 pins and everything in between. Also, they could be single coils or multiple, molded into a single housing.

Does the design of an ignition coil affect how you test it?

Yes. An ignition coil has two elements inside – the primary (the lower voltage) and the secondary (the higher voltage that ignites the spark plug). When testing the coil, you need to test the secondary voltage so it’s important to align the equipment up to that element.

For multiple coils molded into a single housing, you need to use a testing wand. This will pick up the back EMF during operation and send to the oscilloscope for you to review. This will help you identify which coil is causing the problem.

Do I need to test the primary side as well as the secondary?

Before you test the ignition coils, it’s a good idea to check that the primary 12 volt circuit is functioning properly. This is to confirm that the ignition coil has supply voltage and is working correctly.

Should the charge and burn times of the ignition coils be the same?

Not exactly, no. Small differences in the spark plugs will affect their charge and burn times, so expect there to be some variances. However, if one ignition coil was showing its burn time as extremely short or long compared to the others, then this could indicate a fault. The next step would then be to make sure that the spark plug was correct and is gapped correctly.