This procedure covers the removal and replacement of all six spark plugs on the 3.5L EcoBoost V6 engine, including removal of ignition coils and accessing both cylinder banks.

Warnings

Tools required

Parts

• Spark plugs × 6 — Motorcraft SP-546 or equivalent iridium plugs
• Ignition coil boots (if damaged) × 6 — Use OEM specification

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level surface and engage parking brake
3. Disconnect negative battery terminal to prevent accidental cranking
4. Remove engine cover by pulling upward on clips at all four corners
5. Have a clean workspace prepared for removed components

Procedure

1. 1

   Remove air intake system components
   Disconnect the mass airflow sensor electrical connector. Loosen the clamp at the throttle body. Remove the air intake tube by pulling it free from the turbocharger inlet and throttle body connections. Set aside to gain access to the rear cylinder bank.
2. 2

   Access front bank ignition coils (cylinders 1, 2, 3)
   The front bank is the passenger side of the engine. Locate the three ignition coils on top of the valve cover. If any wiring harness brackets or clips obstruct access, remove them and set aside with fasteners organized.
3. 3

   Remove front bank ignition coils
   Disconnect the electrical connector from each ignition coil by pressing the release tab and pulling straight up. Remove the single 10mm bolt securing each coil. Grasp the coil firmly and pull straight up with a twisting motion to break the seal. If coils are stuck, gently rock side-to-side while pulling upward. Inspect coil boots for cracks or oil contamination.
   ⚠Do not pry on ignition coils as this can damage the coil or valve cover.
   Torque spec

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

   Clean spark plug wells on front bank
   Use compressed air to blow out any debris from each spark plug well. Ensure no dirt, leaves, or other contaminants fall into the cylinders when the plugs are removed. Clean around the base of each spark plug.
   ⚠Any debris that enters the cylinder will cause severe engine damage. Ensure plug wells are completely clean.
5. 5

   Remove front bank spark plugs
   Using the 5/8 inch spark plug socket with extension, carefully loosen each spark plug by turning counterclockwise. Once loosened, unscrew by hand to prevent cross-threading. Use the rubber insert in the socket or a magnetic tool to remove the plugs. Inspect each plug for unusual wear, oil fouling, or damage which may indicate engine problems.
6. 6

   Prepare new front bank spark plugs
   Verify the spark plug gap on all new plugs using a gap tool. The specified gap should be 0.028-0.031 inches (check your specific plug specification). Apply a small amount of anti-seize compound to the threads, avoiding the electrode area. Do not over-apply as excess can cause fouling.
   ℹ️Some premium plugs come pre-gapped and should not be adjusted. Verify with plug manufacturer specifications.
7. 7

   Install front bank spark plugs
   Carefully thread each new spark plug by hand into the cylinder head, ensuring they start straight to prevent cross-threading. Once hand-tight, use the torque wrench and spark plug socket to tighten to the specified torque for aluminum heads. Work methodically across all three cylinders.
   ⚠Cross-threading or over-torquing spark plugs in aluminum heads will strip the threads, requiring expensive thread repair.
   Torque spec

   Spark Plug23 Nm (17 lb-ft)
8. 8

   Access rear bank ignition coils (cylinders 4, 5, 6)
   The rear bank is the driver side against the firewall. With the air intake removed, locate the three ignition coils. You may need to remove additional wiring clips or brackets for full access. Work space is more limited on this bank.
9. 9

   Remove rear bank ignition coils
   Disconnect each electrical connector from the rear bank coils. Remove the 10mm bolt from each coil. Pull each coil straight up with a twisting motion. The rear bank coils may require more effort to extract due to limited space. Inspect boots for damage.
   Torque spec

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

    Clean and remove rear bank spark plugs
    Blow out debris from each rear bank spark plug well using compressed air. Remove the three spark plugs using the 5/8 inch spark plug socket with a long extension. Inspect plugs for wear patterns and compare to front bank plugs for consistency.
11. 11

    Install rear bank spark plugs
    Gap and apply anti-seize to the three remaining new spark plugs. Carefully thread each plug by hand, then torque to specification for aluminum heads. Use extra caution in the confined rear bank area to ensure proper socket alignment.
    ⚠The tight working space on the rear bank increases risk of cross-threading. Take extra time to ensure plugs start straight.
    Torque spec

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

    Reinstall all ignition coils
    Apply a thin coat of dielectric grease to the inside of each ignition coil boot. Press each coil firmly into place over its corresponding spark plug until it seats completely. Install and torque the 10mm retaining bolt on each coil. Reconnect all electrical connectors, ensuring they click into place.
    ℹ️Dielectric grease prevents moisture intrusion and makes future coil removal easier. Do not use standard grease.
    Torque spec

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

    Reinstall air intake system
    Position the air intake tube back onto the turbocharger inlet and throttle body. Tighten the throttle body clamp securely. Reconnect the mass airflow sensor electrical connector. Ensure all connections are secure and no hoses are pinched.
14. 14

    Reinstall engine cover and reconnect battery
    Align the engine cover with the four mounting clips 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.

Reassembly

1. Double-check that all six ignition coil electrical connectors are fully seated and locked
2. Verify all removed brackets, clips, and wiring harnesses have been reinstalled
3. Confirm no tools, rags, or parts remain in the engine compartment
4. Ensure air intake system is fully secured with no loose connections

Verification

• Start the engine and listen for smooth idle with no misfires or rough running
• Check for diagnostic trouble codes using an OBD-II scanner - there should be no ignition-related codes
• Rev the engine gently to 2000-3000 RPM and confirm smooth acceleration with no hesitation
• Perform a test drive and verify normal power delivery and no check engine light
• After the first drive cycle, inspect around ignition coils for any signs of arcing or unusual marks
• Monitor fuel economy over the next few tanks - properly gapped new plugs should improve efficiency

More procedures for this vehicle