This procedure covers the removal and replacement of all six spark plugs on the 3.5L EcoBoost V6 engine, including ignition coil removal and proper gapping and torque specifications.

Warnings

Tools required

Parts

• Spark plugs × 6 — Motorcraft SP-553 or equivalent (factory specification)

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level surface and set parking brake
3. Disconnect negative battery terminal to prevent accidental starts
4. Verify new spark plugs are correct specification for the 3.5L EcoBoost engine

Procedure

1. 1

   Remove engine cover
   Grasp the engine cover firmly and pull upward to disengage the retaining clips. The cover is held by push-pin style clips and does not require tools for removal. Set cover aside in a clean area.
2. 2

   Locate and access ignition coils
   Identify all six ignition coil-on-plug assemblies. Three coils are on each cylinder bank. Disconnect the electrical connector from each coil by pressing the release tab and pulling straight up. Mark or photograph coil positions if desired, though they are identical.
3. 3

   Remove ignition coils
   Using an 8mm socket, remove the single bolt securing each ignition coil. Carefully pull each coil straight up and out of the spark plug well with a twisting motion if needed to break the seal. Inspect coil boots for damage or oil contamination.
   ℹ️If oil is present in spark plug wells, valve cover gaskets may need service. Address leaks before completing spark plug replacement.
   Torque spec

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

   Clean spark plug wells
   Use compressed air or a vacuum to remove any debris, dirt, or oil from the spark plug wells. Ensure wells are completely clean before removing spark plugs to prevent contamination from falling into cylinders.
5. 5

   Remove old spark plugs
   Using a 5/8" spark plug socket with rubber insert and appropriate extension, carefully loosen and remove each spark plug. Turn counterclockwise and remove slowly to avoid cross-threading. Inspect old plugs for abnormal wear, carbon buildup, or oil fouling which may indicate engine issues.
6. 6

   Gap new spark plugs
   Using a spark plug gap gauge, verify each new spark plug is gapped to factory specification (typically 0.030-0.032 inches for this engine, verify with plug manufacturer). Adjust gap carefully if needed by bending ground electrode. Do not force or pry against center electrode.
   ℹ️Many modern plugs come pre-gapped, but always verify before installation as gaps can shift during shipping.
7. 7

   Prepare spark plugs for installation
   Apply a small amount of anti-seize compound to the threads of each spark plug if desired (optional but recommended for aluminum heads). Use sparingly - only a thin coating on the threads, avoiding the electrode end. Do not over-apply as excess can contaminate the plug.
8. 8

   Install new spark plugs
   Carefully thread each spark plug by hand into the cylinder head, turning clockwise. Ensure plugs start threading smoothly without resistance. If resistance is felt, remove and restart to avoid cross-threading. Once hand-tight, use torque wrench and spark plug socket to tighten to specification. Note: Two different torque values are listed in database - use 15 Nm (11 lb-ft) as specified for this application and do not overtighten.
   ⚠Cross-threading spark plugs in aluminum heads can cause expensive cylinder head damage. Always start plugs by hand first.
   Torque spec

   Spark Plug23 Nm (17 lb-ft)
9. 9

   Reinstall ignition coils
   Apply a small amount of dielectric grease to the inside of each ignition coil boot if desired (helps prevent moisture and eases future removal). Carefully push each coil down into the spark plug well, ensuring it seats fully onto the spark plug. Install and hand-tighten the 8mm retaining bolt on each coil, then torque to specification.
   ℹ️Ensure coils are fully seated before tightening bolts. Partial seating can cause misfires.
   Torque spec

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

    Reconnect electrical connectors
    Reconnect the electrical connector to each ignition coil, pressing firmly until a click is heard or felt indicating the locking tab has engaged. Verify each connection is secure by gently pulling on the connector.
11. 11

    Reinstall engine cover
    Align the engine cover with the mounting clips and press down firmly at each clip location until cover snaps into place. Verify cover is fully seated and secure.
12. 12

    Reconnect battery and clear codes
    Reconnect the negative battery terminal. If a check engine light was present before the repair, it may need to be cleared using a scan tool, or it will clear itself after several successful drive cycles.

Reassembly

1. Ensure all ignition coil electrical connectors are fully engaged and locked
2. Verify engine cover is properly seated on all mounting clips
3. Double-check that no tools or parts were left in the engine compartment

Verification

• Start engine and verify it runs smoothly without misfires or rough idle
• Check for any check engine lights or misfire codes - clear codes if pre-existing issues are resolved
• Allow engine to reach operating temperature and verify smooth acceleration and no hesitation
• Perform a test drive under light and moderate load to confirm proper operation

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