🔧 Explorer - Spark Plug Replacement

You'll be replacing all six spark plugs on your Explorer to restore smooth running, power, and fuel economy. On this engine, three plugs are easy to reach; the other three require removing the upper intake manifold (the big plastic air passage on top of the engine).

Difficulty Level: Advanced (because of intake removal) | Estimated Time: 3–5 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a cold engine; hot aluminum parts strip easily and can burn you.
• ⚠️ Disconnect the negative battery cable before unplugging coils and sensors to avoid short circuits.
• ⚠️ Keep dirt out of the spark plug holes and intake ports; any debris inside can damage the engine.
• ⚠️ Do not overtighten spark plugs; aluminum cylinder heads strip easily. Always follow the torque spec.
• ⚠️ When the upper intake manifold is off, never drop tools or hardware into the open intake ports.

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🔧 Required Tools

You'll need the following tools for this repair:

• 🛠️ 3/8" drive ratchet
• 🛠️ 1/4" drive ratchet
• 🛠️ 3/8" drive torque wrench (5–60 ft-lbs range)
• 🛠️ 1/4" drive torque wrench (30–120 in-lbs range)
• 🛠️ 10mm socket
• 🛠️ 8mm socket
• 🛠️ 7mm socket
• 🛠️ E8 external Torx socket
• 🛠️ 5/8" spark plug socket (with rubber insert or magnet)
• 🛠️ 3/8" drive extension 3"
• 🛠️ 3/8" drive extension 6"
• 🛠️ Universal joint (3/8" drive)
• 🛠️ Flat trim tool or flathead screwdriver (small)
• 🛠️ Needle-nose pliers
• 🛠️ Spark plug gap gauge (wire or coin type)
• 🛠️ Shop vacuum
• 🛠️ Fender cover or old blanket
• 🛠️ Work light
• 🛠️ Gloves
• 🛠️ Safety glasses

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 🔩 Iridium spark plugs (Ford-spec for 3.3L V6) - Qty: 6
• 🔩 Upper intake manifold gasket set - Qty: 1
• 🔩 Throttle body gasket - Qty: 1
• 🔩 Dielectric grease (for coil boots) - Qty: 1 small tube
• 🔩 Anti-seize compound (high-temp, nickel-based) - Qty: 1 small tube
• 🔩 Shop towels - Qty: 1 pack
• 🔩 Throttle body cleaner (sensor-safe) - Qty: 1 (optional but recommended)

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📋 Before You Begin

• Park the Explorer on level ground, shift to Park, and set the parking brake.
• Open the hood and let the engine cool completely (at least 45–60 minutes).
• Disconnect the negative battery cable using a 10mm socket and move the cable aside so it cannot spring back.
• Remove any plastic engine cover by lifting it up; it is usually held by rubber grommets.
• Lay a fender cover or blanket over the front to protect paint while you lean in.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove air intake duct

• Loosen the clamps on the big black air tube going from the air filter box to the throttle body using an 8mm socket.
• Unplug the mass air flow (MAF) sensor electrical connector by lifting the tab with a flat trim tool and pulling gently.
• Disconnect any small vacuum hoses or resonator tubes attached to the duct by hand or with needle-nose pliers.
• Lift the duct off the airbox and throttle body and set it aside.

Step 2: Remove visible front-bank ignition coils

• The ignition coils are the small black units on top of the engine with a single electrical connector; each coil sits over a spark plug.
• Unplug the electrical connector from each of the three front coils by pressing the tab with a flat trim tool and pulling straight back.
• Remove each coil hold-down bolt using a 7mm socket.
• Gently twist and pull each coil upward to remove it from the spark plug well. Twist first to break the rubber seal.

Step 3: Clean and remove front spark plugs

• Use a shop vacuum and a small nozzle to suck out any dirt around each spark plug hole.
• Install the 5/8" spark plug socket onto a 3/8" extension and ratchet.
• Carefully loosen each spark plug by turning counterclockwise. If a plug feels very tight, gently work it back and forth instead of forcing it.
• Once loose, remove the ratchet and spin the extension by hand to finish unscrewing the plug, then lift it out.

Step 4: Prepare and install new front spark plugs

• Check the gap on each new plug with a spark plug gap gauge. It should be about 0.031–0.035 in (0.8–0.9 mm). The plugs should be pre-gapped; do not bend the tiny center electrode if it is iridium.
• Lightly coat only the plug threads with a very thin film of anti-seize compound. Too much changes torque.
• Place the new plug into the 5/8" spark plug socket and lower it into the hole by hand.
• Thread each plug in by hand (no ratchet) until fully seated. If you feel resistance right away, back it out and start again to avoid cross-threading.
• Attach the torque wrench to the extension and tighten each plug to 20 Nm (15 ft-lbs).

Step 5: Reinstall front ignition coils

• Put a tiny dab of dielectric grease inside each coil boot opening.
• Push each coil straight down onto its plug until it seats fully.
• Reinstall the coil hold-down bolts using a 7mm socket and torque to 8 Nm (71 in-lbs).
• Plug in the coil electrical connectors until they click.

Step 6: Prepare to remove upper intake manifold for rear bank

• The rear three spark plugs are under the upper intake manifold (the large black plastic piece on top, toward the firewall).
• Label any vacuum hoses or connectors you remove with tape and a marker. Helps during reassembly.
• Unplug sensors and connectors attached to the manifold and throttle body using your fingers or a flat trim tool.
• Remove any small brackets attached to the manifold with an 8mm socket or E8 external Torx socket.

Step 7: Remove throttle body and manifold bolts

• Unplug the throttle body electrical connector.
• Remove the throttle body mounting bolts using an 8mm socket. Carefully pull the throttle body away and set it aside with hoses still attached if possible.
• Remove the upper intake manifold mounting bolts using a 10mm socket. There are several across the top and possibly some at the rear—note their positions.
• Keep bolts in order; you can poke them into cardboard with labels.

Step 8: Lift off upper intake manifold

• Gently lift the intake manifold up and toward the front of the vehicle. If it feels stuck, check for any missed bolts or hoses before pulling harder.
• Once free, flip it over or move it carefully to a clean area; do not stress attached hoses.
• Cover the now-exposed intake ports on the engine with clean shop towels to prevent anything from falling in.

Step 9: Remove rear ignition coils and spark plugs

• Unplug the electrical connectors for the three rear coils by hand or with a flat trim tool.
• Remove the coil hold-down bolts using a 7mm socket and pull out the coils.
• Use the shop vacuum to clean around the rear plug wells.
• Use the 5/8" spark plug socket, extension, and possibly a universal joint with your ratchet to remove the three rear spark plugs just as you did the front ones.

Step 10: Install new rear spark plugs

• Check gap with the spark plug gap gauge again and lightly coat threads with anti-seize compound (thin film).
• Start each plug by hand to avoid cross-threading.
• Torque each rear plug to 20 Nm (15 ft-lbs) with the torque wrench.

Step 11: Reinstall rear ignition coils

• Apply a small dab of dielectric grease to each rear coil boot.
• Install the coils, push them fully down onto the plugs, and reinstall the hold-down bolts with a 7mm socket.
• Tighten the coil bolts to 8 Nm (71 in-lbs).
• Reconnect all coil electrical connectors until they click.

Step 12: Install new intake gaskets and intake manifold

• Remove the old upper intake manifold gaskets from the manifold (they are usually rubber rings) and clean the sealing surfaces with a clean shop towel.
• Install the new upper intake manifold gasket set into the grooves in the manifold.
• If you removed the throttle body, install a new throttle body gasket as well.
• Remove the shop towels covering the intake ports, making sure nothing falls in.
• Carefully lower the intake manifold back into position on the engine, aligning the bolt holes and ports.

Step 13: Torque manifold and throttle body

• Install the intake manifold bolts by hand first, then snug them with a 10mm socket.
• Torque the intake manifold bolts in a criss-cross pattern to 15 Nm (11 ft-lbs) using your torque wrench.
• Reinstall the throttle body with an 8mm socket and torque the bolts to 10 Nm (89 in-lbs).
• Reconnect all electrical connectors, vacuum hoses, and brackets you removed earlier using the appropriate 8mm socket or E8 external Torx socket.

Step 14: Reinstall air intake duct and reconnect battery

• Reinstall the air intake duct onto the airbox and throttle body, then tighten the clamps with an 8mm socket.
• Reconnect the MAF sensor and any other sensors or hoses on the duct.
• If your Explorer has an engine cover, push it back into place.
• Reconnect the negative battery cable using a 10mm socket and tighten snugly.

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✅ After Repair

• Start the engine and let it idle. It may run slightly rough for a few seconds while the computer relearns.
• Listen for hissing noises (vacuum leaks) around the intake manifold and throttle body. If you hear a hiss, shut off the engine and recheck hoses and bolts.
• Verify that the Check Engine light stays off. If it was on before for misfires, it may clear after a few drive cycles or you can clear it with a scan tool.
• Take a short test drive, checking for smooth acceleration and no hesitation.

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💰 DIY vs Shop Cost

Shop Cost: $450–$750 (parts + labor)

DIY Cost: $90–$180 (parts only)

You Save: $360–$570 by doing it yourself!

Shop labor rates vary but typically run $100–$150/hour. This repair takes a shop approximately 2–3 hours.

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🎯 Ready to get started?

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