2021 Toyota Tundra Spark Plug Type & Gap

Quick reference

Why the right plug matters

Spark plugs are a critical component of your 2021 Toyota Tundra's ignition system, responsible for igniting the air-fuel mixture in the combustion chamber. Using the correct spark plug for your specific engine, as well as maintaining the proper gap, is crucial for optimal engine performance, fuel efficiency, and longevity.

Heat Range: Spark plugs are designed with a specific "heat range," which refers to their ability to dissipate heat. A plug that's too hot can lead to pre-ignition and engine damage, while a plug that's too cold can cause fouling and misfires. The factory-specified plug for your 5.7L V8 3UR-FE engine is precisely engineered for its operating temperatures.

Electrode Metal: Modern spark plugs utilize different electrode materials, each with its own advantages:

• Iridium: These are the most common type for modern vehicles like your Tundra. Iridium is extremely hard and has a high melting point, allowing for very fine electrodes and extended life (typically 100,000 miles or more). They provide excellent ignitability and durability.
• Platinum: Platinum plugs offer good durability, often lasting 60,000-80,000 miles. They are a step up from copper but generally don't match the lifespan of iridium.
• Copper: While excellent conductors, copper plugs have thicker electrodes and a shorter lifespan (around 20,000-30,000 miles). They are rarely found as OEM on modern, high-performance engines.

For your 2021 Toyota Tundra, the OEM specifies Iridium spark plugs, which offer the best balance of performance and longevity.

How to gap a spark plug

While most iridium spark plugs come pre-gapped from the factory, it's always a good practice to verify the gap before installation, especially if they've been jostled during shipping. The gap for your 2021 Tundra's 5.7L V8 is 0.043 inches (1.1 mm).

To gap a spark plug, you'll need a wire-type spark plug gapping tool. Avoid using flat disc-style gapping tools on fine-wire iridium plugs, as they can damage the delicate electrode.

1. Measure: Gently slide the appropriate wire gauge into the gap between the center and ground electrodes.
2. Adjust (if necessary): If the gap is too small, use the gapping tool to very carefully and slightly bend the ground electrode outward. If the gap is too large, gently tap the ground electrode on a hard, non-abrasive surface to close the gap. Be extremely careful not to touch or damage the center iridium electrode.
3. Re-measure: Confirm the gap is correct before installation.

Replacement procedure tips

Replacing the spark plugs on your 2021 Toyota Tundra 5.7L V8 is a manageable DIY job for those with some mechanical experience. Here are a few tips:

• Cool Engine: Always let your engine cool completely before starting. Working on a hot engine can lead to burns and can also make plug removal more difficult if they're seized.
• Coil-on-Plug Removal: Your Tundra uses a coil-on-plug ignition system. Each spark plug has an individual ignition coil sitting directly on top of it. Carefully disconnect the electrical connector from each coil, then unbolt the coil (usually a 10mm bolt) and pull it straight up to remove it. Be gentle to avoid damaging the coil or its rubber boot.
• Anti-Seize Debate: There's ongoing debate about using anti-seize on spark plug threads. For plugs with nickel-plated shells, like the Denso plugs in your Tundra, manufacturers often advise against using anti-seize. The plating itself provides anti-seize properties, and adding more can lead to over-torquing and potential thread damage, or even alter the electrical grounding path. Always refer to the spark plug manufacturer's recommendations. Toyota likely specifies dry threads for their OEM plugs.
• Dielectric Grease on Boots: Apply a small amount of dielectric grease to the inside of the spark plug boot (the rubber part that connects to the top of the spark plug). This helps seal out moisture, prevents corrosion, and makes future removal easier. Avoid getting grease on the spark plug electrodes.
• Torque Wrench: Use a torque wrench for installation. Overtightening can strip threads or damage the spark plug, while undertightening can cause misfires and allow combustion gases to escape. The specified torque for your Tundra's spark plugs is 13 lb-ft (18 Nm).

Known issues

The 2021 Toyota Tundra 5.7L V8 engine (3UR-FE) is generally known for its reliability, and unlike some other manufacturers, there are no widespread, specific known issues related to spark plug breakage or unique ignition system challenges that typically plague this engine platform. As long as you use the correct OEM or equivalent quality spark plugs and follow the recommended replacement intervals and procedures, you should experience trouble-free operation.

Need plugs replaced? Find a shop on Repairius.