🔧 F-150 - Spark Plug Replacement

This is a manageable intermediate job if you work on a completely cold engine and replace one plug at a time. Your F-150 uses six coil-on-plug ignition coils, with one coil directly above each spark plug.

Difficulty Level: Intermediate | Estimated Time: 2-3 hours

Key specifications: Check each new plug at 0.028-0.031 in (0.7-0.8 mm), following Ford’s current online specification. Tighten each plug to 15 Nm (133 in-lbs). fordservicecontent.com)

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⚠️ Safety & Precautions

• 🧊 Let the engine become completely cold before removing plugs from the aluminum cylinder heads.
• 🔋 Disconnect the negative battery terminal before unplugging the ignition coils.
• 🧹 Clean every plug well before removal. Dirt dropped into a cylinder can cause serious damage.
• ✋ Start every new plug by hand. A ratchet can hide cross-threading until the expensive part begins.
• 🚫 Don’t use an impact wrench for spark plug removal or installation.
• ⚠️ Stop if a plug binds sharply. Work it gently back and forth rather than forcing it.

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🔧 Required Tools

You'll need the following tools for this repair:

• 8mm socket
• 10mm socket
• 7mm socket
• 3/8-inch drive ratchet
• 3/8-inch drive 3-inch extension
• 3/8-inch drive 6-inch extension
• 3/8-inch drive universal joint
• 14mm thin-wall spark plug socket
• Inch-pound torque wrench rated below 200 in-lbs
• 0.028-0.031-inch wire spark plug gap gauge
• Compressed-air blow gun with regulated nozzle
• Flat-blade screwdriver
• Small plastic trim tool
• Clean shop vacuum with narrow nozzle
• Mechanic gloves
• Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Catalog-matched spark plugs - Qty: 6
• Ignition coil boots - Qty: 6 only if cracked, swollen, oil-soaked, or carbon-tracked
• Dielectric grease - Qty: 1 small tube

I’d use the catalog-matched OE-style plugs shown in the parts sidebar. Avoid the cold-range performance set unless your F-150 is modified or tuned.

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📋 Before You Begin

• 🅿️ Park on level ground, select Park, apply the parking brake, and open the hood.
• 🧊 Leave the engine off until the cylinder heads are cold to the touch.
• 🔋 Use a 10mm socket to loosen the negative battery-terminal clamp. Isolate the cable so it cannot spring back.
• 📦 Keep each ignition coil beside its original cylinder unless you intend to diagnose a misfire.
• 🧼 Work on one cylinder at a time so nothing falls into an open plug well.
• 📏 Check the gap gently with a wire gauge. Don’t pry against the fine center electrode.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Remove the oil-fill cap by hand if it passes through the engine cover.
• Pull the engine cover upward at its mounting points using both hands.
• Reinstall the oil-fill cap immediately so nothing enters the engine.
• Photograph the engine bay before disconnecting anything.

Step 2: Remove the intake duct where necessary

• Use a 7mm socket or flat-blade screwdriver to loosen the intake-tube clamps.
• Disconnect any breather hose or electrical connector attached to the duct. Press the locking tab rather than pulling on the wires.
• Move the duct aside without forcing the attached hoses.

Step 3: Disconnect the first ignition coil

• Use a small plastic trim tool to release the electrical connector lock.
• Press the connector tab and pull the connector straight away from the coil.
• Use an 8mm socket and ratchet to remove the coil hold-down bolt.
• Twist the coil slightly, then pull it straight upward by its body.
• Inspect the rubber boot for oil, moisture, cracking, or thin black carbon-tracking lines.

Step 4: Clean the spark plug well

• Wear safety glasses before using compressed air.
• Use a shop vacuum around the top of the plug well first.
• Use a regulated compressed-air blow gun to clear the well completely.
• Don’t remove the plug until the well is clean. Turbo engines already have enough excitement without feeding them gravel.

Step 5: Remove the old spark plug

• Seat the 14mm thin-wall spark plug socket squarely over the plug.
• Use the 6-inch extension and 3/8-inch ratchet to loosen the plug slowly.
• Use the universal joint only where access requires it. Keep the socket as straight as possible.
• Once loose, turn the extension by hand and lift the plug out.
• Stop if porcelain is visibly broken or pieces appear missing.

Step 6: Inspect and prepare the new plug

• Compare the new and old plugs for matching thread length, seat design, and overall reach.
• Use the wire gap gauge to verify 0.028-0.031 in (0.7-0.8 mm). Ford’s current specification lists this range for the 3.5L EcoBoost. fordservicecontent.com
• Don’t coat the plug threads with anti-seize unless the plug manufacturer specifically requires it. Added lubricant changes tightening force.

Step 7: Install the new spark plug

• Place the plug into the 14mm spark plug socket.
• Lower it straight into the well using only the extension.
• Turn the extension clockwise by hand for several complete turns.
• If it doesn’t spin smoothly, remove it and restart. Never pull it into the threads with the ratchet.
• Use the inch-pound torque wrench to tighten the plug to 15 Nm (133 in-lbs). youtube.com

Step 8: Reinstall the ignition coil

• Apply a tiny amount of dielectric grease inside the opening of the rubber coil boot. Keep it off the plug threads and metal terminal.
• Push the coil straight down until the boot seats firmly over the plug.
• Install the coil hold-down bolt using the 8mm socket.
• Use the inch-pound torque wrench to tighten the coil bolt to 6 Nm (53 in-lbs). Ford service material for this 3.5L EcoBoost ignition system specifies 53 in-lbs. device.report)
• Reconnect the electrical connector until its lock clicks.

Step 9: Replace the remaining five plugs

• Repeat Steps 3 through 8 for each remaining cylinder.
• Use the 3-inch extension or universal joint where rear access is restricted.
• Keep the spark plug socket straight so it doesn’t press against and crack the porcelain.
• Replace a coil boot if you find cracking, oil saturation, or carbon tracking.

Step 10: Reassemble the intake system

• Reinstall every breather hose and electrical connector removed earlier.
• Position the intake duct fully over its sealing lips.
• Use the 7mm socket or flat-blade screwdriver to tighten the clamps firmly without crushing the plastic duct.
• Confirm that no tools, rags, or loose connectors remain in the engine bay.

Step 11: Reinstall the engine cover and battery cable

• Remove the oil-fill cap by hand if required for cover installation.
• Align and press the engine cover onto its mounting points.
• Reinstall the oil-fill cap securely.
• Use the 10mm socket to reconnect and secure the negative battery-terminal clamp.

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✅ After Repair

• 🚙 Start the engine and let it idle for several minutes.
• 👂 Listen for a steady idle, clicking, hissing, or a puffing noise from a loose plug.
• ⚠️ Shut the engine off immediately if the check-engine light flashes or the engine misfires severely.
• 🔍 Inspect every ignition-coil connector, breather hose, and intake clamp again.
• 🛣️ Take a short, gentle road test before applying heavy boost.
• 📱 The clock and some saved settings may need restoration after disconnecting the battery.

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💰 DIY vs Shop Cost

Shop Cost: $300-$550 (parts + labor)

DIY Cost: $60-$140 (parts only, depending on plug and boot condition)

You Save: $160-$490 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.5-2.5 hours. Local Sonīpat labor pricing may be lower than these U.S.-market estimates.

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