2015 Ford Transit Spark Plug Type, Gap, & Torque

Quick reference

Why the right plug matters

Spark plugs are more than just simple igniters; they are a critical component in your 2015 Ford Transit's ignition system, directly impacting engine performance, fuel efficiency, and emissions. Using the correct spark plug for your specific engine—whether the 3.7L Ti-VCT V6 or the 3.5L EcoBoost V6—is paramount.

Heat Range

Every spark plug is designed with a specific "heat range." This refers to its ability to dissipate heat from the combustion chamber. A plug that's too "hot" (dissipates heat slowly) can lead to pre-ignition and engine damage, while a plug that's too "cold" (dissipates heat too quickly) can foul with carbon deposits, leading to misfires. The OEM-specified plugs for your Transit are carefully selected for optimal heat range, ensuring efficient combustion and preventing issues.

Electrode Metal: Iridium vs. Platinum

For the 2015 Ford Transit, you'll find that the OEM and recommended aftermarket plugs are typically iridium or platinum. These precious metals are chosen for their exceptional durability and resistance to wear, allowing for much longer service intervals compared to traditional copper plugs.

• Iridium: Extremely hard and boasts a very high melting point, allowing for fine-wire electrodes that provide a more focused and powerful spark. This contributes to better fuel economy and reduced emissions.
• Platinum: Offers excellent corrosion and wear resistance. While not as hard as iridium, double-platinum plugs (platinum on both the center and ground electrodes) provide extended life by minimizing gap erosion.

Never "upgrade" to a copper plug if your engine specifies iridium or platinum. The heat range and design characteristics are vastly different, leading to poor performance and potential engine damage.

How to gap a spark plug

While many modern iridium and platinum spark plugs come "pre-gapped" from the factory, it's always a good practice to double-check the gap before installation, especially for the sensitive EcoBoost engine. Even a slight discrepancy can affect ignition efficiency.

1. Obtain the correct gap specification for your engine (refer to the table above).
2. Use a wire-type spark plug gapping tool. Avoid using a ramp-style tool, as it can damage fine-wire electrodes.
3. To increase the gap, gently bend the ground electrode outwards with the gapping tool.
4. To decrease the gap, carefully tap the ground electrode on a clean, solid surface until the desired gap is achieved.
5. Re-check the gap to ensure accuracy.

Replacement procedure tips

Replacing spark plugs on your 2015 Ford Transit, particularly the 3.5L EcoBoost, requires attention to detail. Both engines use a coil-on-plug (COP) ignition system, meaning each spark plug has its own ignition coil directly mounted on top of it.

1. Access: The engine cover will need to be removed to access the coils. On the 3.5L EcoBoost, the intake manifold may also need to be removed for easier access to the rear bank of spark plugs. This is a more involved procedure, so be prepared with new intake manifold gaskets.
2. Coil-on-Plug Removal: Carefully disconnect the electrical connector from each coil pack, then remove the hold-down bolt (if present). Gently twist and pull the coil pack straight up to remove it. Avoid excessive force, as the coil boot can sometimes stick to the spark plug.
3. Anti-Seize Debate: There is ongoing debate about using anti-seize on spark plug threads. Ford, like many manufacturers, generally recommends against it for modern spark plugs with nickel-plated shells. The nickel plating provides adequate anti-seize properties, and adding more can alter the torque readings, potentially leading to over-tightening and plug breakage or damage to cylinder head threads. Follow Ford's recommendation and do NOT use anti-seize unless explicitly stated in a service bulletin for your specific vehicle.
4. Dielectric Grease: Apply a small amount of dielectric grease inside the spark plug boot (the rubber part that connects to the spark plug porcelain). This helps to seal out moisture, prevents corrosion, and makes future removal easier. Do NOT apply dielectric grease to the spark plug threads or the electrode tip.
5. Torque Matters: Always use a torque wrench to tighten spark plugs to the manufacturer's specification (refer to the table). Over-tightening can damage the spark plug and the cylinder head threads, while under-tightening can lead to combustion gas leaks and misfires.

Known issues

Fortunately, the 2015 Ford Transit does not suffer from the widespread spark plug breakage issues that plagued some earlier Ford 3-valve modular engines (e.g., the 5.4L Triton). The spark plugs specified for the 3.7L Ti-VCT and 3.5L EcoBoost are robust and generally do not present unique removal challenges beyond typical maintenance.

However, proper care and adherence to replacement intervals are still crucial, especially with the EcoBoost engine, which places higher demands on its ignition system due to forced induction.

Need plugs replaced? Find a shop on Repairius.