This procedure covers the inspection and replacement of ignition coils on the 2021-2024 Ford F-150 3.5L EcoBoost V6 engine, as this engine uses coil-on-plug ignition with no traditional spark plug wires.

Warnings

Tools required

Parts

• Spark plugs (set of 6) × 6 — Motorcraft SP-546 or equivalent
• Ignition coils (if faulty) × 6 — Use OEM specification

Preparation

1. Ensure engine is completely cool to the touch
2. Park vehicle on level ground and engage parking brake
3. Disconnect negative battery cable to prevent accidental engine start
4. Remove engine cover by pulling upward on cover to release retaining clips

Procedure

1. 1

   Access ignition coils
   Locate all six ignition coils on top of the engine. On the 3.5L EcoBoost, three coils are on each cylinder bank. Remove any wiring harness clips or brackets that may restrict access to the coils. Disconnect the electrical connector from each ignition coil by pressing the release tab and pulling straight up.
2. 2

   Remove ignition coils
   Using a 10mm socket, remove the single bolt securing each ignition coil. Carefully pull each coil straight up with a twisting motion to break the seal. Inspect the coil boot for damage, cracking, or oil contamination. If boots are damaged, replace the coils.
   Torque spec

   Ignition Coil Bolt12 Nm (9 lb-ft)
3. 3

   Clean spark plug wells
   Use compressed air to blow out any debris, dirt, or oil from around each spark plug well. This prevents contamination from falling into the cylinder when plugs are removed. If oil is present in the wells, inspect valve cover gaskets for leaks.
   ⚠Excessive oil in spark plug wells indicates a valve cover gasket leak that should be addressed to prevent future ignition coil failure.
4. 4

   Remove spark plugs
   Using a spark plug socket with extension, carefully remove each spark plug by turning counterclockwise. Keep plugs organized by cylinder position for inspection. Examine each plug for wear, deposits, or damage to diagnose engine condition.
5. 5

   Inspect and gap new spark plugs
   Verify new spark plugs match the correct specification for your engine. Check and adjust the gap on each new plug to 0.030-0.033 inches (0.76-0.84mm) using a gap tool. Even if plugs are pre-gapped, verify before installation.
   ℹ️The 3.5L EcoBoost requires iridium or platinum spark plugs. Do not use conventional copper plugs.
6. 6

   Install new spark plugs
   Apply a small amount of anti-seize compound to the threads of each new spark plug, avoiding the electrode area. Thread each plug by hand into the cylinder head to prevent cross-threading. Once hand-tight, use a torque wrench to tighten to specification. The F-150 3.5L EcoBoost has aluminum heads, so use the aluminum head specification.
   Torque spec

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

   Prepare ignition coils
   Apply a thin coating of dielectric grease to the inside of each ignition coil boot. This helps prevent moisture intrusion and makes future removal easier. Ensure the coil boots are clean and free from cracks or damage.
8. 8

   Install ignition coils
   Carefully push each ignition coil straight down onto its corresponding spark plug until it seats fully. You should feel and hear a positive click when the coil boot engages the spark plug terminal. Install the 10mm retaining bolt for each coil and torque to specification.
   Torque spec

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

   Reconnect electrical connectors
   Reconnect the electrical connector to each ignition coil, ensuring each connector clicks securely into place. Reinstall any wiring harness clips or brackets that were removed for access.
10. 10

    Reinstall engine cover and battery
    Align engine cover with mounting clips and press down firmly until all clips engage. Reconnect the negative battery cable. The vehicle may need to relearn idle and fuel trims during initial operation.
    Torque spec

    Engine Cover Clips3 Nm (2 lb-ft)

Reassembly

1. Ensure all ignition coil electrical connectors are fully seated and locked
2. Verify all tools and parts are removed from engine bay
3. Double-check that engine cover is properly secured

Verification

• Start engine and listen for smooth idle with no misfires or rough running
• Check for any diagnostic trouble codes using an OBD-II scanner
• Verify no check engine light illumination
• Test drive vehicle under light and moderate acceleration to confirm smooth operation
• Inspect spark plug wells and surrounding areas for any signs of oil leaks after test drive

More procedures for this vehicle