WOOFIXING Iridium Spark Plugs for Ford 5.4L V8 — 8-Pack SP515/SP546, OE-Fit & Long-Life

WOOFIXING SP515 / SP546 iridium spark plugs are a direct-fit eight-piece replacement engineered to restore consistent ignition for Ford 5.4L and compatible 4.6L V8 engines.

These spark plugs are manufactured to match OE specifications for late-model Ford/Lincoln/Mercury V8 engines, providing a plug-and-play option for 2004–2008 F-150, F-250, F-350 (including Super Duty), Expedition, Mustang, and various Lincoln/Mercury models. Each set contains eight iridium-tipped plugs designed to deliver steady high-voltage transfer, long electrode life, and improved throttle response when installed correctly. SP515 and SP546 share compatibility across many vehicles; SP515 tends to suit older engine variants while SP546 aligns with more recent factory requirements. Check your vehicle’s manual or part lookup to confirm the correct code before ordering.

How do these plugs affect everyday driving performance?

Replacing worn plugs with these iridium units helps return smooth idling and consistent acceleration by ensuring reliable combustion across all cylinders. The iridium tip maintains spark integrity longer than standard electrodes, which supports more even firing and helps prevent misfires under load.

• Eight plugs per package for complete V8 tune-ups.
• Iridium electrode for longer service life and consistent spark.
• Engineered to meet factory gap and heat-range expectations.
• Helps improve throttle response and reduce rough idle when worn plugs were the issue.

Are these spark plugs compatible with my Ford or Lincoln model?

These plugs are designed for a range of Ford/Lincoln/Mercury V8 applications, especially 5.4L and many 4.6L engines from model years roughly 2004–2008. Compatibility includes F-150, Expedition, Mustang, F-250/F-350 Super Duty, Lincoln Navigator, and Mercury Mountaineer within the specified years, but you should verify part numbers or VIN-fitment just to be certain.

• Common OE references: SP515, SP-515, SP546, SP-546, SP507, PZH14F, PZT2F.
• Also cross-referenced to codes like SP546X and several factory aftermarket catalog numbers.
• SP515 favored for older engine assemblies; SP546 used more by newer factory specifications.
• Ideal for complete V8 replacements—eight plugs included per set.

What installation steps and torque settings should I follow?

Proper installation prevents leaks and ensures a solid electrical connection. Use a torque wrench and tighten to the manufacturer-recommended setting to avoid damaging the threads or ignition components.

• Recommended torque: 25–30 N·m (2.5–3.0 kgf·m).
• Use anti-seize only if specified by your shop manual; many iridium plugs come pre-coated.
• Replace eight plugs for V8 engines to maintain balanced performance.
• Inspect coil boots and ignition wiring while plugs are out; replace if cracked or worn.

What quality checks and warranty considerations apply?

Each spark plug receives rigorous quality control testing to ensure consistent high-voltage output and electrode integrity. WOOFIXING emphasizes stable ignition performance and longer service life through material selection and testing protocols.

• Iridium tips tested for durability and consistent gap retention.
• High-voltage conduction checked to reduce misfire risk.
• Packaged as a complete eight-plug set for V8 engines to simplify maintenance.
• Follow product listing or retailer terms for warranty details and returns.

Who is this for: This eight-pack is ideal for DIY mechanics and service shops replacing all spark plugs on Ford 5.4L or compatible 4.6L V8 engines from the mid-2000s range. If you drive an F-150, F-250, F-350 Super Duty, Expedition, Mustang, Lincoln Navigator, or Mercury Mountaineer from roughly 2004–2008 and want a long-lasting iridium replacement that meets OE cross-references (SP515/SP546), these plugs offer a practical maintenance upgrade. Always confirm the correct SP code for your engine variant before purchase and use a torque wrench to ensure a proper, long-lasting installation.