Ignition Wire Buying Guide

Jefferson Bryant

March 20, 2025

6 min read

Jefferson Bryant

March 20, 2025

6 min read

Ignition wires, also referred to as plug wires, are your engine’s connection to the ignition system.

Your engine’s design uses one of three types of ignition systems. All of them use plug wires that are identical in construction but vary in length and terminal style.

Individual coils are typically mounted on the valve cover and have short wires that connect them to the spark plugs.
Coil banks, popularly used on Ford engines in the 1990s, usually control four spark plugs with four different length wires.
Engines with distributors use one wire per cylinder, each a different length—plus one coil wire that connects to the coil.

Preventing Interference and Detonation

A modern V-8 engine with individual coils on each spark plug, resting on a wooden crate. — A modern engine with spark plug wires has individual coils with a single wire connected to the spark plug.

Spark plug wires use high voltage, typically around 45,000. But that could go as high as 100,000 volts for high-performance engines. This voltage must be contained in the jacket. The voltage can also bring electromagnetic interference (EMI) and radio frequency interference (RFI). These are strong signals that interfere with your vehicle’s electrical system. It is most often heard via your audio system as a high-pitched whirring or buzzing that changes pitch with the engine rpm.

When a plug wire is failing, the EMI and RFI get past the insulation and start causing problems. Besides annoying noise in the radio, these signals can cause serious engine damage. Sparks from two adjacent plug wires, if weak, can interfere with one another, causing the plugs to fire at the wrong time. This is called detonation. One jumped spark is enough to make your engine misfire. If it happens too much, it can break your pistons.

Standard Versus High-Performance Spark Plug Wires

A weathered V-8 engine in an older vehicle, with a single ignition coil. — Older vehicles with distributors have long plug wires that wrap around the engine to each spark plug position.

Most vehicles don’t need expensive spark plug wires. A standard set will get your car down the road just fine.

However, if your engine is modified for high performance, then upgrading from stock to high-performance wires is worth the upcharge. If you run high-performance wires and spark plugs, you could see an increase in fuel economy and performance. But it won’t be dramatic.

Most OEM ignition wires—the ones that come with your vehicle when new or purchased from the manufacturer—are made with a carbon fiberglass core. This is the part that carries the voltage from the coil to the plug. Carbon core wires do not last as long as high-performance wires. As the carbon breaks down, the core wires develop more resistance and can emit more EMI, which interferes with electrical signals throughout the vehicle.

Standard OEM plug wires are designed to reduce EMI over resistance, so an OEM wire has more resistance, yielding a lower spark voltage getting to the plug. Inexpensive carbon core wires typically have an EPDM rubber inner jacket and outer jacket. Because EPDM rubber is less durable, it breaks down faster.

High-performance wires upgrade the core materials to Kevlar or a spiral core that uses stainless steel, copper, and tin to reduce EMI. The wires use silicon jackets, which are more resistant to heat, chemicals, and abrasion, so the wires last longer.

Aftermarket high-performance plug wires put a premium on lower resistance, allowing more EMI over an OEM wire and more voltage to flow. In the end, high-performance plug wires rarely cause engine noise in the radio, but it is possible. Again, for most vehicles, carbon core plug wires are well-suited for the job.

Spark Plug Wires That Fit Your Car

A mechanic wearing black nitrile gloves removing the spark plug wires from the distributor cap. The spark plug wires are labeled with blue tape. — Label plug wires before removing them. Swap out one wire at a time.

Finding the right plug wires for your vehicle is easy using the eBay Parts Finder - opens in new window or tab. . Enter your vehicle’s info, and eBay will present you with the available products that match your vehicle and search parameters.

Plug wires are vehicle-specific. The lengths must be correct for each engine. DIYers should buy their wires as a pre-made matched set. You can always opt for a cut-to-fit wire set, but you must make sure the terminals fit your engine. And you need a special crimping tool to terminate the ends. Pre-made sets are the easiest way to go for most vehicles.

How much should you spend on ignition wires?

The average cost of a set of plug wires with a basic carbon core is between $45 and $60. A high-performance set costs $75 to $300.

You can buy wires for less than $45, but that compromises longevity and performance. Low-cost wires do not last nearly as long as premium wires. They have higher resistance and lower EMI suppression.

OEM brands like AC Delco, Bosch, Delphi, Denso, and NGK are excellent. MSD, Scott, and Taylor are considered the best available high-performance plug wires.

How long do ignition wires last?

Premium plug wires last up to 100,000 miles. Some engines can rack up 150,000 miles on one set of plug wires. But here’s the rule of thumb: For the best performance, change the plug wires every 60,000 to 100,000 miles.

Change Spark Plugs and Wires at the Same Time

A mechanic wearing black nitrile gloves installs a new distributor cap. — We recommend changing the ignition cap, rotor, and spark plugs when replacing the wires.

Most engines built after the late 1990s do not have distributors, so a tune-up on these engines is just the plugs and wires. Individual ignition coils usually last 100,000 miles or more, so you can change them with the plug wires. But this is generally not done as a maintenance item. Instead, replace the ignition coils on an as-needed basis. Distributor ignition systems use a single coil, which should be replaced when doing a full tune-up.

If you are changing plugs at the same time, you only need a ratchet with a spark plug socket to match your plugs. A standard deep-well socket works just as well.

Changing plug wires typically does not require any tools unless you need to remove a component to get to them. The one thing you need is dielectric grease or silicone paste. That electrically safe grease keeps the plug wire boots from bonding to the plugs and cap/coil. It also insulates the connection from air and moisture so that they do not corrode, which inhibits conductivity.

About the author

Jefferson Bryant

A lifelong gearhead, Jefferson Bryant got his first car when he was two: a Fisher-Price convertible. An industry veteran for over 30 years, Jefferson started in car audio, working his way up to product designer for Rockford Fosgate. He has written nine books and countless magazine articles about automotive technology. Jefferson also produces tech videos on YouTube. His pride and joy is a 1971 Buick GS Convertible with a swapped Procharged Gen V LT1, which he used to drive his newborn kids home from the hospital.

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This article is meant to provide general guidance only. Automotive maintenance, repair, upgrade, and installation may depend on vehicle-specifics such as make and model. Always consult your owner's manual, repair guide for specific information for your particular vehicle and consider a licensed auto-care professional's help as well, particularly for advance repairs.