2018 Ford Explorer Spark Plug Type & Gap

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2018 Ford Explorer is crucial for optimal engine performance, fuel efficiency, and longevity. Spark plugs are not a "one-size-fits-all" component, and using the wrong type can lead to a host of problems.

Heat Range: Spark plugs are designed with a specific "heat range" that determines how quickly heat is dissipated from the tip. A plug that's too "hot" (dissipates heat slowly) can lead to pre-ignition and engine knocking, potentially causing severe damage. Conversely, a plug that's too "cold" (dissipates heat too quickly) can foul up with carbon deposits, leading to misfires and poor performance. Each engine in the 2018 Ford Explorer is engineered for a specific heat range, and the OEM and recommended aftermarket plugs reflect this.

Electrode Metal: The material used for the electrodes significantly impacts the plug's lifespan and performance.

• Iridium: These plugs are the most durable and offer the longest lifespan (typically 100,000 miles or more). Iridium is extremely hard and resistant to wear, allowing for a finer electrode tip and a stronger spark. Both the 3.5L Duratec and EcoBoost engines in the Explorer often use iridium plugs as OEM.
• Platinum: Platinum plugs are a step up from copper, offering better durability and a longer lifespan (around 60,000-80,000 miles). They use a platinum disc welded to the center electrode. Some aftermarket options for your Explorer may utilize platinum.
• Copper: While excellent conductors, copper plugs have a much shorter lifespan due to the softer nature of the metal. They are rarely found in modern engines like those in the 2018 Explorer due to their frequent replacement intervals. However, if you find an aftermarket copper plug listed, be aware of the shorter replacement schedule.

How to gap a spark plug

Correct spark plug gap is vital for a strong, consistent spark. The gap is the distance between the center and ground electrodes. An incorrect gap can lead to misfires, reduced fuel economy, and potential engine damage. While many modern spark plugs come pre-gapped, it's always a good idea to double-check.

1. Obtain a gap gauge: A wire-type gap gauge or a feeler gauge is ideal. Avoid using a ramp-style coin-type gauge as it can damage fine-wire iridium or platinum electrodes.
2. Check the gap: Carefully insert the correct size wire or blade from your gauge between the electrodes. It should slide in with a slight drag.
3. Adjust (if necessary): If the gap is too small, use the adjustment tool on your wire gauge to gently bend the ground electrode outwards. If the gap is too wide, carefully tap the ground electrode on a clean, hard surface to close the gap. Never bend the center electrode, especially on fine-wire plugs, as this can damage the plug.
4. Re-check: Always re-check the gap after any adjustment.

Important Note for EcoBoost Engines: The EcoBoost engines often have tighter gap specifications than naturally aspirated engines. Precision is key. Follow the exact specifications in the quick reference table above.

Replacement procedure tips

Replacing spark plugs on your 2018 Ford Explorer is a relatively straightforward DIY task for the mechanically inclined, but there are a few tips to ensure a smooth process.

• Coil-on-Plug (COP) Removal: The 2018 Explorer uses a coil-on-plug ignition system. This means each spark plug has its own ignition coil directly mounted on top. To access the plugs, you'll need to carefully disconnect the electrical connector from each coil and then remove the retaining bolt(s) before gently pulling the coil straight up and off the spark plug. Be gentle to avoid damaging the coil boot or the electrical connector.
• Anti-Seize Debate: There's ongoing debate regarding the use of anti-seize on spark plug threads. Ford, like many manufacturers, generally recommends against it for plugs with nickel-plated shells, as the plating itself acts as an anti-seize. Applying additional anti-seize can alter the torque readings, potentially leading to over-tightening and plug breakage or stripping threads. If you choose to use it (e.g., on older, non-plated plugs), use a very small amount and reduce the torque specification by about 20%.
• Dielectric Grease on Boots: Applying a thin layer of dielectric grease inside the spark plug boot (the rubber part that connects the coil to the plug) is highly recommended. This helps prevent moisture intrusion, insulates against voltage leaks, and makes future removal easier.
• One at a Time: Work on one spark plug at a time. This helps prevent accidentally mixing up coil connectors or dropping debris into an open cylinder.
• Cleanliness: Before removing any spark plugs, use compressed air to blow any debris around the spark plug wells. This prevents dirt and grime from falling into the combustion chamber once the old plug is removed.

Known issues

Fortunately, the 2018 Ford Explorer engines do not have any widespread, notoriously problematic spark plug issues similar to the earlier Ford 3-valve 2-piece spark plug breakage. The engines in your Explorer are generally robust, and with proper maintenance and the correct spark plugs, you should avoid any known issues related to spark plugs.

Always ensure you use the correct spark plugs with the specified gap and torque to prevent misfires, premature wear, and costly repairs.

Need plugs replaced? Find a shop on Repairius.