This procedure covers a minor tune-up for the 2021-2024 Ford F-150 with the 3.5L EcoBoost V6 engine, including spark plug replacement, air filter replacement, and cabin filter replacement.

Warnings

Tools required

Parts

• Spark plugs × 6 — Motorcraft SP-546 or equivalent iridium plugs
• Engine air filter × 1 — Motorcraft FA-1927 or equivalent
• Cabin air filter × 1 — Motorcraft FP-67 or equivalent

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure engine is completely cool to the touch (wait at least 2 hours after operation)
3. Open hood and secure with prop rod
4. Disconnect negative battery terminal if working near electrical connections

Procedure

1. 1

   Remove engine cover
   Grasp the engine cover firmly and pull upward to disengage the retaining grommets. The cover is friction-fit and does not require tools. Set aside in a clean area.
2. 2

   Access and remove air filter housing
   Release the air box clips on both sides of the air filter housing. Carefully lift the top portion of the air box to access the engine air filter. Remove the old air filter and inspect the housing for debris or moisture.
   Torque spec

   Air Box Clips5 Nm (4 lb-ft)
3. 3

   Install new engine air filter
   Insert the new engine air filter into the housing, ensuring proper orientation with any arrows pointing in the direction of airflow. Reseat the air box top and secure the clips on both sides until they click into place.
   Torque spec

   Air Box Clips5 Nm (4 lb-ft)
4. 4

   Replace cabin air filter
   Open the glove box and remove contents. Press inward on both sides of the glove box to release the stops and lower it fully. Remove the cabin air filter access door by pressing the tabs. Slide out the old cabin filter, noting the airflow direction arrows. Insert the new cabin filter with arrows pointing in the correct direction, reinstall the access door, and restore the glove box to normal position.
5. 5

   Locate and access spark plugs
   The 3.5L EcoBoost has three spark plugs on each cylinder bank. Identify all six ignition coils on top of the engine. You may need to remove or relocate some hoses or wiring for better access, particularly around the turbochargers.
6. 6

   Remove ignition coils
   Disconnect the electrical connector from each ignition coil by pressing the release tab and pulling straight up. Remove the single bolt securing each coil using a socket wrench. Carefully pull each coil straight up with a twisting motion to break the seal. Inspect coil boots for damage or oil contamination.
   ℹ️If coil boots are damaged or oil-soaked, inspect for valve cover leaks before proceeding.
   Torque spec

   Connector Bolts8 Nm (6 lb-ft)
7. 7

   Remove old spark plugs
   Use a spark plug socket with extension to remove each spark plug. Turn counterclockwise carefully, ensuring the socket is fully seated to prevent rounding. Once loose, remove by hand to avoid dropping. Inspect old plugs for abnormal wear, oil fouling, or electrode damage which may indicate engine issues.
8. 8

   Prepare and gap new spark plugs
   Verify the gap on each new spark plug is set to manufacturer specification (typically 0.035 inches for this engine, but verify with plug packaging). Apply a small amount of anti-seize compound to the threads (avoiding the electrode end). Do not apply dielectric grease to the threads.
   ⚠Use anti-seize sparingly. Excess can contaminate the combustion chamber or interfere with proper torque.
9. 9

   Install new spark plugs
   Carefully thread each new spark plug by hand into the cylinder head, ensuring straight threading. Once hand-tight, use the torque wrench to tighten to 12 Nm (9 lb-ft). Work systematically through all six cylinders. Do not over-torque as the aluminum heads are susceptible to thread damage.
   ⚠If a spark plug does not thread easily by hand, stop and verify alignment. Cross-threading will require expensive cylinder head repair.
10. 10

    Reinstall ignition coils
    Apply a thin coat of dielectric grease to the inside of each coil boot. Push each ignition coil firmly into place over its respective spark plug until fully seated. Install the retaining bolt for each coil and torque to specification. Reconnect the electrical connector to each coil until it clicks.
    Torque spec

    Connector Bolts8 Nm (6 lb-ft)
11. 11

    Reinstall engine cover and final checks
    Align the engine cover with the retaining grommets and press down firmly until it seats completely. Reconnect the negative battery terminal if it was disconnected. Verify all tools and parts have been removed from the engine bay.

Reassembly

1. Ensure all electrical connectors are fully seated and locked
2. Verify engine cover is properly secured to all mounting grommets
3. Check that air filter housing clips are fully engaged
4. Confirm no tools or rags remain in engine compartment

Verification

• Start the engine and listen for smooth idle with no misfires or unusual sounds
• Allow engine to reach operating temperature and verify no check engine light appears
• Rev engine gently to 2000-3000 RPM and confirm smooth acceleration with no hesitation
• Perform a short test drive to verify normal performance and throttle response
• Re-check that all ignition coil connectors remain properly seated after test drive

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