Replace all six spark plugs on the 3.5L EcoBoost engine to maintain proper ignition and engine performance.

Warnings

Tools required

Parts

• Motorcraft spark plugs SP-515 or equivalent iridium plugs × 6 — Motorcraft SP-515

Preparation

1. Ensure engine is completely cold to the touch
2. Disconnect negative battery terminal to prevent accidental starter engagement
3. Verify replacement spark plugs are correct for 3.5L EcoBoost (gapped to 0.035 inches/0.9mm)
4. Park vehicle on level surface and engage parking brake
5. Gather all tools and parts before beginning work

Procedure

1. 1

   Remove engine cover
   Remove the plastic engine cover by lifting upward firmly to release the mounting grommets. The cover is held by clips and may require moderate force to release. Set cover aside in clean area.
   Torque spec

   Engine Cover Clips3 Nm (2 lb-ft)
2. 2

   Access driver side spark plugs (cylinders 1, 2, 3)
   Locate the three ignition coils on the driver side of the engine. These are positioned on top of the valve cover. Note the routing of any wiring harnesses or vacuum lines that may need to be moved aside for access.
   ℹ️Driver side plugs (front of engine) are more accessible than passenger side.
3. 3

   Remove driver side ignition coils
   Disconnect the electrical connector from each ignition coil by pressing the release tab and pulling straight up. Remove the single 7mm bolt securing each coil using the 7mm socket. Carefully pull each coil straight up with a twisting motion to release it from the spark plug well. Inspect coil boots for damage or oil contamination.
   ⚠Do not pull on wiring harness. Grasp the coil body only.
   Torque spec

   Ignition Coil Bolt12 Nm (9 lb-ft)
4. 4

   Clean spark plug wells (driver side)
   Use compressed air or a vacuum to remove any debris, dirt, or oil from the spark plug wells. This prevents contamination from falling into the cylinders when plugs are removed. Ensure wells are completely clean before proceeding.
   ⚠Any debris that falls into cylinder can cause serious engine damage.
5. 5

   Remove driver side spark plugs
   Using the 5/8 inch spark plug socket with extension, carefully loosen each spark plug by turning counterclockwise. Once loose, unthread by hand using the socket to prevent cross-threading. Remove all three driver side plugs and inspect for unusual wear, oil fouling, or carbon buildup. Set plugs aside for comparison with new plugs.
   ℹ️Inspect old plugs for signs of engine problems such as oil burning, running too rich/lean, or pre-ignition.
6. 6

   Gap and install new driver side spark plugs
   Verify each new spark plug is gapped to 0.035 inches (0.9mm) using the gap tool. Apply a small amount of anti-seize compound to the threads if desired (optional, as plugs often come pre-treated). Carefully thread each plug into the cylinder head by hand using the spark plug socket to ensure proper alignment. Once seated, torque to 15 Nm (11 lb-ft) using the torque wrench. Do not exceed this specification.
   ⚠Thread plugs by hand first. If resistance is felt, stop and re-align to prevent cross-threading.
   Torque spec

   Spark Plug23 Nm (17 lb-ft)
7. 7

   Reinstall driver side ignition coils
   Apply a thin coat of dielectric grease to the inside of each coil boot if desired. Align each coil over its spark plug and push down firmly until it seats completely. Install the 7mm bolt for each coil and torque to 12 Nm (9 lb-ft). Reconnect the electrical connectors to each coil until they click into place.
   Torque spec

   Ignition Coil Bolt12 Nm (9 lb-ft)
8. 8

   Access passenger side spark plugs (cylinders 4, 5, 6)
   Locate the three ignition coils on the passenger side of the engine. Access is restricted by the brake master cylinder, wiring harnesses, and coolant reservoir. Carefully move aside any wiring or hoses as needed without disconnecting them. Use extensions and universal joints if necessary for limited access areas.
   ℹ️Passenger side requires more patience due to tight working space. Consider removing air intake tube for additional clearance.
9. 9

   Remove passenger side ignition coils
   Disconnect the electrical connector from each ignition coil by pressing the release tab. Remove the 7mm bolt from each coil. Carefully extract each coil from the spark plug well using a twisting and pulling motion. The rear-most coil (cylinder 6) may require the most effort due to limited access.
   Torque spec

   Ignition Coil Bolt12 Nm (9 lb-ft)
10. 10

    Clean spark plug wells (passenger side)
    Thoroughly clean each spark plug well using compressed air or vacuum to remove all debris. Pay special attention to the rear cylinder which may accumulate more debris due to limited airflow in that area.
    ⚠Ensure all debris is removed before plug removal to prevent cylinder contamination.
11. 11

    Remove and replace passenger side spark plugs
    Remove each spark plug using the 5/8 inch spark plug socket with appropriate extensions. Verify new plugs are gapped to 0.035 inches. Apply anti-seize if desired. Thread new plugs by hand, then torque to 15 Nm (11 lb-ft). The rear cylinder may require a longer extension and careful alignment.
    ⚠Use extra care with rear plug due to limited visibility and access. Ensure proper thread engagement before tightening.
    Torque spec

    Spark Plug23 Nm (17 lb-ft)
12. 12

    Reinstall passenger side ignition coils
    Apply dielectric grease to coil boots if desired. Install each coil by pressing down firmly until seated. Install and torque the 7mm bolts to 12 Nm (9 lb-ft). Reconnect all electrical connectors ensuring they lock into place. Verify all wiring and hoses are properly routed and not pinched.
    Torque spec

    Ignition Coil Bolt12 Nm (9 lb-ft)
13. 13

    Reinstall engine cover and reconnect battery
    Position the engine cover over the mounting grommets and press down firmly until all clips engage. Reconnect the negative battery terminal. Ensure all tools and parts have been removed from the engine bay.
    Torque spec

    Engine Cover Clips3 Nm (2 lb-ft)

Reassembly

1. Double-check that all six ignition coil electrical connectors are fully seated and locked
2. Verify engine cover is properly secured to all mounting points
3. Ensure no tools or debris remain in engine bay

Verification

• Start engine and listen for smooth idle with no misfires or unusual sounds
• Allow engine to reach operating temperature and verify no check engine light illuminates
• Perform a test drive and confirm smooth acceleration with no hesitation or misfires under load
• Use a scan tool to verify no misfire codes (P0300-P0306) are present
• Inspect around ignition coils for any sign of spark arcing or oil leaks after test drive

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