So You’ve Fouled Up...

Your spark plug’s electrode or porcelain tip has a shiny black appearance and just isn’t working like it should. This is what happens when oil finds its way into the combustion chamber.

What Do You Do Now?

Plugs should make it to the recommended service interval without issue, as long as you pick the right metallurgy for your needs and make sure to install them correctly. If fouling is causing misfires long before the plugs are supposed to be changed, you’ve got a bigger problem on your hands.

Oil fouling is one of the most common types, but it could be a sign of something more serious – advanced engine wear. If you start to see oil deposits on your spark plugs, you need to diagnose the cause before you get right into plug replacement.

How Did Oil Get in There Anyway?

Oil doesn’t belong in the combustion chamber, but piston rings, valve stem seals or the PCV system can have other ideas. Here are a few things you can try to get to the bottom of it:

• Run a leak-down test on your piston rings.
• Try a compression check to see if a particular cylinder has issues.
• See if the PCV is running at high pressure or the valve is constantly open.

Not only can these tests save you from ruining even more plugs, they can save your engine from continued damage. Last time I checked, those cost a pretty penny too.

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How’s Your Torque?

Give those spark plugs the right twist or your engine could end up paying the price. These are the steps the pros follow:

It Doesn’t Take a Genius to Understand GDI

To all my people who loved the garage more than school growing up, I’m sure you’ve heard about the way engines are trending. Gasoline Direct Injection (GDI) engines continue to grow in popularity, and if you have one (or are working on one for your ungrateful relatives, friends, kids, etc.), you’ll need to understand its particular ignition needs.

Auto manufacturers have leaned into GDI technology for a reason. This type of engine delivers better performance and fuel economy over conventional fuel injection systems, but it also comes with unique service requirements and challenges. Yes, these requirements include specific spark plug needs.

The Ignition Challenges of GDI Engines

The key difference in these engines is that they directly inject fuel at high pressure into the combustion chamber. Because this process is more likely to fuel wash spark plugs than indirect fuel-injection systems or conventional carburetors, a GDI engine calls for spark plugs with more focused ignition.

Here’s another factor you should consider when it comes to GDI. More complete combustion and cooler temperatures inside the cylinder lead to an enhanced compression ratio that delivers better efficiency and power with the same amount of fuel. BUT these cool temperatures can also be more likely to create carbon fouling.

Direct injection also brings the risk of introducing small amounts of dirt in the air and blowback carbon build up on intake walls. This carbon buildup could restrict air flow to the cylinders, causing the loss of torque and fuel economy.

So, the main advantage of GDI technology – its precision – makes finding the right plug just a little more difficult. To keep these engines running cleanly and efficiently, you need to know your metallurgy.

Get it Right with Help from Autolite^®

Focused ignition, an optimal heat range and superior fouling resistance are a winning combo for any engine, but they are non-negotiable for direct injection. That’s why you’ve gotta get iridium.

Autolite^® offers two options in this category, Iridium Ultra^® and Iridium XP, both are proven to deliver high power, long life and exceptional value. Iridium XP offers an ignition upgrade for older vehicles, while Iridium Ultra^® is an ideal OE replacement, especially in late models.

Look at you, you’re a GDI expert now!

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Gapping Impacts Spark Plug Performance

I’m not British, but I still think mind the gap is some of the most useful advice I can give. Successful ignition and kick-ass performance are only possible with the right spark plug gap.

This gap, or the proper distance between the center and ground electrodes, is a delicate balance. Proper distances come down to a tenth of a millimeter or four thousandths of an inch. Without the right distance, the plug may not be able to ignite the air-fuel mixture or create the necessary combustion to start an engine.

Get It Juuuust Right

Too small of a gap and the flame kernel may not have enough room to expand. Too large and the voltage required from the coil may be too great. Because spark plugs are precision-made, any adjustment has the potential to greatly affect that performance we crave. This is especially true of new iridium plugs.

Even though iridium spark plugs can potentially deliver more than 100,000 miles of ignition, 0.6mm or 0.5mm iridium finewire can be destroyed during gapping. A combination of a steady hand and a trusty gapping tool is needed to take on this task.

Tool Up

A wire loop gauge is the ONLY gapping tool that is Annie-approved. It’s accurate and offers damage-free operation when used properly. With a selection of wire loops and a hook, this gauge helps in measuring the gap, gently bending the electrode and then re-measuring until correct. Let me say this again. This should be the only gapping tool used in your shop, especially when it comes to iridium finewire.

Before you get to work, look up the right gap as recommended in your owner’s manual or Autolite Spark Plug Catalog.

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Guys, It’s All About the Tip...

...when it comes to the metallurgy of your spark plug electrode.

Why Metallurgy Matters

The makeup, or metallurgy, of the plug’s conductive material can be the difference maker for mileage, service life, fuel efficiency and fouling resistance. Some metals are more resistant to corrosion, are better at resisting fouling and can be machined into a fine wire to produce more focused ignition.

As much as I love fancy words, let’s break down what this means when you’re shopping for new plugs. Here are your electrode options and what they have to offer:

Which One Do You Want?

Copper has long been the standard, but newer model vehicles may require a minimum metallurgy of iridium. I can’t stress this enough - check OE specifications when selecting the most applicable aftermarket spark plugs.

If performance is your priority, consistent ignition and quicker acceleration makes iridium the way to go. These plugs can handle a greater mileage load than copper or platinum.

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Annie’s Essential Ignition Tools

When it comes to installing or removing spark plugs, an eye for detail and a little bit of elbow grease are every bit as necessary as the stuff you keep in your toolchest.

As for the actual tools, I’ve got recommendations there too. Installing and removing spark plugs on your own isn’t tricky, but the right tools go a long way in making it a smooth process.

Here’s what you’ll need:

1. Torque wrench: I prefer a torque wrench over a ratcheting socket wrench because of how precise you can get with one. When you’re tightening your plugs, you want to be sure you’re getting them just right. Since spark plugs are precision-made, installing them with precision tools is a must. Plus, over-torquing is never OK.
2. Spark plug-recommended sockets: Avoid putting excess stress on your spark plugs’ ceramic insulator by using sockets that are specifically recommended for use with spark plugs. They’ll usually come with a rubber insert to surround and hold the insulator during installation. (Bonus points if your socket has a magnet to hold the plug terminal in place. This makes removing your old, used plugs WAY easier.)
3. Wire loop gauge: Gauging the gap on your plugs is a real Goldilocks situation. Too small and the flame kernel may not have enough room to expand. Too large and the voltage required from the coil may be too great. A wire loop gauge provides accurate measurements and damage-free operation when used properly. I can’t say it enough – a wire loop gauge should be the ONLY gapping tool used in your shop.
4. Thread chaser: A plug will sometimes tighten too quickly when you’re turning it in by hand. In cases like this, a thread chaser can be used to clean the threads and make sure your plugs are spinning in smoothly.
5. Cleaning supplies: They might not be formal automotive tools, but things like a vacuum/compressed air blower and a clean rag are always good to have on hand. I might like getting my hands dirty, but auto parts generally don’t appreciate dust, dirt and grime.

And that’s it! Now you know the Annie-approved list of tools you’ll need to successfully remove and install spark plugs on your own.

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Install Plugs the Annie Way

1. Grab a socket, the right size socket extensions, a gapping tool and dielectric grease.
2. For wires, grasp the plug wire boot and twist it about one-quarter turn to loosen the seal. Then, pull the boot straight off. Don’t forget to number plug wires with tape as you remove them to avoid crossing them, or just disconnect one at a time. If your vehicle is coil-on-plug, disconnect the coil connectors, remove the hold-down bolts and remove the coils.
3. Before loosening each spark plug, clean dirt or fluids out of the seat area with compressed air, a shop vacuum or blowing around the spark plug through a soda straw in a pinch.
4. Remove plugs and line them up in cylinder order. Give them a thorough look to see if there is any damage or irregularity. The Autolite^® plug tip inspection guide can help with this part.
5. Gap new plugs as recommended in owner’s manual or Autolite^® Spark Plug Catalog. ONLY use a wire loop gauge.
6. Screw new plugs in by hand until tight. If a plug tightens up too soon while turning them in by hand, use a thread chaser to clean the threads. Use a torque wrench to tighten to proper specifications.
7. Inspect the plug wires and boots (or the coils and boots on coil-on-plug systems) for brittleness or cracking, and check for corrosion on the terminals inside each boot. Replace suspect coils, boots and or wires as needed. Lubricate the plug contact area inside each boot with dielectric grease and then reinstall the plug wires.
8. Start ‘er up! Misfires or a rough idle can mean the wires are in the wrong order or loose. Recheck firing order and coil connections closely if the engine still isn’t running right.

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Choose Your Socket Wisely

When installing or removing spark plugs, make sure not to stress the ceramic insulator. An uneven socket could cause cracks, and eventually misfires. The easiest way to avoid this issue is to pick a socket recommended for use with spark plugs. Usually, this type of socket will come with a rubber insert to surround and hold the insulator during installation. An even more helpful socket feature is a magnet that can hold the plug terminal in place to make removal from the engine easier.

Spark-plug-specific sockets will often have a hex bolster on the drive end, allowing the use of a wrench to increase usability in hard-to-reach locations. Most engines use either 5/8” or 13/16” hex spark plugs, but if you’re unsure what size socket you’ll need, you can use newly purchased spark plugs to locate a correctly sized socket while at the store.

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No One Likes Pre-Ignition

Pre-ignition can cause severe spark plug damage. This condition occurs when the ignition of the fuel-air mixture happens before the spark plug is ignited, and it’s more likely when you pick a plug with too hot of a heat range for the application.

Hot spots, carbon build-ups in the combustion chamber, lean fuel conditions caused by PCV contamination and low octane fuel are a few other potential causes. No matter the cause, there is a good way to tell if this is happening under your hood. If the ground electrode and insulator are damaged, you could be dealing with pre-ignition.

Prevent pre-ignition and the damage it can cause by using a plug in the recommended heat range for your application, and of course, maintain your engine with regular maintenance.

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