🔧 Expedition - Spark Plug Replacement

On your Expedition’s 3.5L turbo engine, spark plugs wear over time and can cause misfires, rough idle, and poor fuel economy. This job is mostly remove-and-replace, but access is tighter on the rear plugs near the firewall, so take your time.

Difficulty Level: Intermediate | Estimated Time: 1.5-3.0 hours

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⚠️ Safety & Precautions

• ⚠️ Let the engine cool fully before starting (hot aluminum threads can strip).
• ⚠️ Keep dirt out of the spark plug holes; debris can damage the cylinder.
• ⚠️ Do not pull on wiring—pull on connectors only.
• ⚠️ Battery disconnect is not required, but keep the key off and stay clear of moving parts.
• ⚠️ If a plug feels “stuck,” stop and work it out slowly to avoid thread damage.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 1/4" drive ratchet
• 3/8" drive ratchet
• 8mm socket
• Flat trim tool
• 5/8" spark plug socket
• 3/8" torque wrench (10-30 ft-lbs range)
• 6" extension (3/8" drive)
• 12" extension (3/8" drive)
• Universal swivel joint (3/8" drive)
• Compressed air blow gun
• Flashlight
• Small pick tool

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Spark plugs (OEM-spec, iridium) - Qty: 6
• Dielectric grease - Qty: 1
• Ignition coil boots (optional, if torn/oil-soaked) - Qty: 6

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📋 Before You Begin

• Park on level ground, shift to Park, and set the parking brake.
• Let the engine cool for at least 1 hour.
• Have a clean place to line up parts by cylinder so nothing gets mixed up.
• Tip: Do one cylinder at a time.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Grip the engine cover and pull upward to release it from the mounting grommets (use a flat trim tool if it’s stubborn).
• Set it aside where it won’t get stepped on.

Step 2: Make room to access the coils

• Use a flashlight to identify the ignition coils (one coil sits on top of each spark plug).
• If the air inlet tube or resonator blocks access on the passenger side, loosen/remove the fasteners using an 8mm socket and move the ducting aside.

Step 3: Unplug and remove one ignition coil

• Press the electrical connector lock and unplug the coil (use a small pick tool gently only if the lock is stuck).
• Remove the coil hold-down bolt using an 8mm socket.
• Twist the coil slightly and pull straight up to remove it.
• Tip: Don’t yank—twist breaks the seal.

Step 4: Clean the plug well

• Blow out the spark plug well with a compressed air blow gun so debris can’t fall into the cylinder.

Step 5: Remove the old spark plug

• Install a 5/8" spark plug socket on a 3/8" ratchet with a 6" extension.
• For the rear plugs, add a 12" extension and a universal swivel joint to reach around obstacles.
• Turn counterclockwise to remove the plug, then lift it out with the socket.

Step 6: Install the new spark plug (start by hand)

• Put the new plug into the 5/8" spark plug socket and lower it into the hole.
• Thread it in by hand using just the extension (no ratchet at first) to avoid cross-threading.
• Once it seats, torque it using a 3/8" torque wrench: Torque to 15 Nm (11 ft-lbs).
• Tip: If it won’t thread easily, back out and retry.

Step 7: Reinstall the ignition coil

• Apply a small dab of dielectric grease inside the coil boot (this helps prevent sticking and moisture issues).
• Push the coil straight down until it fully seats on the plug.
• Install the coil bolt using an 8mm socket, then snug it (small bolt—do not over-tighten). If using a torque wrench: Torque to 5 Nm (44 in-lbs).
• Reconnect the electrical connector until it clicks.

Step 8: Repeat for the remaining 5 cylinders

• Repeat Steps 3–7 one cylinder at a time.
• Use the universal swivel joint (3/8" drive) and extensions for the rear bank as needed.

Step 9: Reassemble and reinstall the engine cover

• Reinstall any air ducting you moved using an 8mm socket.
• Press the engine cover back onto its mounts until it snaps into place.

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✅ After Repair

• Start the engine and let it idle for 1–2 minutes. It should run smooth with no shaking.
• If the check engine light comes on or it runs rough, re-check that every coil connector is fully clicked in.
• Take a short test drive and confirm no hesitation under light acceleration.
• Tip: A flashing CEL means stop and re-check work.

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💰 DIY vs Shop Cost

Shop Cost: $300-$650 (parts + labor)

DIY Cost: $60-$180 (parts only)

You Save: $240-$470 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-3.0 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.