How to Install Spark Plugs on a 2005-2008 Mustang

Investing in a high-performance 2005-2008 Mustang can be a rewarding experience for many enthusiasts. There are plenty of engine mods that can boost your Mustang’s power and give you a high-octane driving experience.

If you’ve added any mods to your 2005-2008 Mustang that result in a higher than stock cylinder combustion pressure or sustained high RPMs, it’s important to upgrade the stock spark plugs to ensure your engine runs at maximum efficiency. Check out the step-by-step instructions below for a full breakdown of how to install performance spark plugs on a 2005-2008 Mustang GT.

Early S197 Mustang Spark Plug Install Steps

Parts and Tools Needed:

• Ratchet and 9/16 Inch Deep Socket
• Torque Wrench
• Nickel Anti-Seize
• Dielectric Grease
• Spark Plug Gap Tool

For this install, we chose the Mustang Cold Spark Plug Set from Ford Racing. If you have a different set, check the fitment to ensure it matches your Mustang’s year and model. These Ford Racing cold spark plugs are one heat range colder than stock GT plugs for improved performance over the factory setup.

Step 1: Loosen Coil Bolts and Remove Coils

Unplug the coil on the stock plugs and fuel injector connectors. Loosen the coil bolts with a 7mm socket. Remove the coils.

Step 2: Remove Spark Plugs

Remove the spark plugs with a 9/16 inch deep socket or a 9/16 inch spark plug socket.

Step 3: Gap the New Spark Plugs

The new plugs may need to be gapped, depending on the motor's configuration. The new plugs should be gapped to 0.032 inches for a supercharged motor. The 0.002-inch strap spring back is accounted for by gapping to 0.030 inches. A specialized tool is available to gap your Mustang’s spark plugs. It can also be done with a vise, screwdriver, spark plug socket, and feeler gauge as shown below.

Check your Mustang’s engine configuration to determine the proper spark plug gap for your setup.

Step 4: Apply Anti-Seize Coating

Apply a thin coating of nickel anti-seize to the barrel of the new spark plug. This will prevent carbon build-up between the plug and the head. Note that the threads are pre-lubed from the factory and do not require additional anti-seize.

Step 5: Apply Grease to Coil

Apply dielectric grease to the coil found above the spark plug boots.

Step 6: Install New Spark Plugs

Install the new spark plugs using a 9/16 inch deep socket or a 9/16 inch spark plug socket. Torque the spark plugs to 25 ft. lbs.

Reinstall the factory coil packs. Connect the coil and injector plugs to the factory locations.

Find the Best Spark Plugs for Your Mustang

Adding new spark plugs to your 2005-2008 Mustang is a critical step if you’re planning on modding your engine for higher combustion pressure. It’s also important to find the right spark plugs for your Mustang, as having the wrong plugs can cause catastrophic problems for your engine.

Be sure to check the manufacturer’s recommendations as well as your Mustang’s engine specs to ensure you’re getting the right spark plugs that will improve engine efficiency and high RPM performance. Check out our wide selection of Mustang spark plugs below for everything you need to take your S197 Mustang to the next level.