Replace all six spark plugs on the 3.5L EcoBoost V6 engine, including removal of engine covers and ignition coils to access spark plug wells.

Warnings

Tools required

Parts

• Spark plugs × 6 — Motorcraft SP-546 or equivalent iridium plugs gapped to 0.030"

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level surface and engage parking brake
3. Disconnect negative battery terminal to prevent accidental starter engagement
4. Verify replacement spark plugs are correct part number and pre-gap to 0.030" specification
5. Apply light coat of anti-seize compound to spark plug threads (avoid getting any on electrodes)

Procedure

1. 1

   Remove engine cover
   Remove the plastic engine cover by pulling upward firmly on the cover to release the press-fit clips. The cover may require twisting motion while pulling. Some models have additional 10mm bolts that must be removed first.
   Torque spec

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

   Access Bank 1 spark plugs (passenger side)
   Locate the three ignition coils on the passenger side cylinder head. Disconnect the electrical connector from each coil by pressing the release tab and pulling straight up. Label or photograph connector positions if desired, though they are keyed and cannot be reversed.
3. 3

   Remove Bank 1 ignition coils
   Remove the 7mm or 10mm bolt (depending on model year) securing each ignition coil. Pull coils straight up with steady pressure to remove from spark plug wells. If coils are stuck, gently twist while pulling upward. Inspect coil boots for cracks or damage.
   Torque spec

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

   Clean spark plug wells - Bank 1
   Use compressed air or shop vacuum to thoroughly clean debris from each spark plug well before removal. Any dirt or debris that falls into the cylinder can cause engine damage. Ensure wells are completely clean before proceeding.
   ⚠Critical step: debris in cylinders will score cylinder walls and damage pistons
5. 5

   Remove Bank 1 spark plugs
   Using 5/8" spark plug socket with extension, carefully loosen each spark plug 1-2 turns. If significant resistance is felt, stop and verify correct socket engagement. Once loose, unscrew plugs by hand to prevent cross-threading. Remove all three plugs and inspect for unusual wear, oil fouling, or electrode damage.
   ⚠Never force spark plug removal. Excessive force indicates cross-threading or carbon buildup requiring penetrating oil
6. 6

   Install Bank 1 new spark plugs
   Start each new spark plug by hand, threading at least 3-4 full turns to ensure proper thread engagement. Use spark plug socket and torque wrench to tighten to specification. Install plugs one at a time to avoid mixing up cylinder positions.
   Torque spec

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

   Reinstall Bank 1 ignition coils
   Apply thin layer of dielectric grease to inside of coil boots. Insert coils into spark plug wells, ensuring they seat fully onto spark plugs. Install and torque retaining bolts. Reconnect electrical connectors until they click into place.
   Torque spec

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

   Access Bank 2 spark plugs (driver side)
   On driver side, you may need to move wiring harnesses and hoses aside for access. Disconnect electrical connectors from all three ignition coils on driver side cylinder head. Some technicians find it helpful to remove the engine air intake tube for additional clearance, though not always necessary.
9. 9

   Remove Bank 2 ignition coils
   Remove the retaining bolt from each ignition coil using 7mm or 10mm socket. Pull coils straight up out of wells. Driver side coils may require more effort due to tighter clearances. Work carefully to avoid damaging coil boots on surrounding components.
   Torque spec

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

    Clean spark plug wells - Bank 2
    Thoroughly clean each spark plug well with compressed air or vacuum. Pay extra attention on driver side as debris accumulation may be greater due to restricted airflow in engine bay. Verify wells are completely clean before removing plugs.
11. 11

    Remove Bank 2 spark plugs
    Use 5/8" spark plug socket with appropriate extensions to access driver side plugs. Rear-most plug may require longer extension and careful positioning. Loosen each plug 1-2 turns, then remove by hand. Inspect removed plugs for wear patterns and compare to passenger side plugs.
    ℹ️Driver side rear plug is most difficult to access. Take your time to avoid damaging threads
12. 12

    Install Bank 2 new spark plugs
    Thread each new spark plug by hand first, being especially careful with the rear plug where visibility is limited. Once hand-tight, torque each plug to specification using torque wrench. Verify all three driver side plugs are properly seated.
    Torque spec

    Spark Plug23 Nm (17 lb-ft)
13. 13

    Reinstall Bank 2 ignition coils
    Apply dielectric grease to coil boots. Install all three coils into spark plug wells, ensuring full seating. Install and torque retaining bolts. Reconnect all electrical connectors. Reposition any wiring harnesses or hoses moved during disassembly.
    Torque spec

    Ignition Coil Bolt12 Nm (9 lb-ft)
14. 14

    Reinstall engine cover and final checks
    Align engine cover with mounting clips and press firmly until all clips engage. If equipped with bolts, install and torque to specification. Reconnect negative battery terminal. Verify all electrical connectors are secure and no tools remain in 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 with all clips engaged
3. Ensure no tools, rags, or parts were left in engine compartment

Verification

• Reconnect battery and start engine. Engine should start immediately and idle smoothly without misfires
• Allow engine to reach operating temperature and verify smooth acceleration with no hesitation or misfires
• Check for any unusual noises from spark plug wells that might indicate improper coil seating
• If check engine light illuminates or rough running occurs, use scan tool to check for misfire codes and recheck installation of affected cylinder
• Test drive vehicle under various loads to confirm proper operation across all RPM ranges

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