🔧 Murano - Spark Plug Replacement

On your Murano’s 3.5L V6, the front 3 spark plugs are easy to reach, but the rear 3 sit under the upper intake manifold (plenum). You’ll remove the plenum to access the rear bank, then replace all 6 plugs and reinstall everything with new gaskets to prevent vacuum leaks.

Difficulty Level: Intermediate | Estimated Time: 2.5–4.5 hours

Assumption: 3.5L V6 (coil-on-plug) with upper intake plenum removal for rear plugs.

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⚠️ Safety & Precautions

• ⚠️ Work on a cold engine to avoid burns and stripped threads.
• ⚠️ Disconnect the negative battery cable to prevent accidental shorts.
• ⚠️ Keep dirt out of the intake ports—stuff clean rags in openings immediately.
• ⚠️ Do not over-tighten spark plugs; aluminum heads strip easily.
• ⚠️ If you unplug many connectors, label them with tape to avoid mix-ups.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 3/8" drive ratchet
• 1/4" drive ratchet
• 3/8" drive torque wrench (10–60 ft-lbs range)
• 1/4" drive torque wrench (inch-lb range)
• 10mm socket
• 12mm socket
• 14mm socket
• 6" extension (3/8" drive)
• 10" extension (3/8" drive)
• Wobble extension (3/8" drive)
• Swivel/universal joint (3/8" drive)
• 5/8" spark plug socket (rubber insert or magnetic)
• Flathead screwdriver
• Pick tool
• Pliers
• Trim clip removal tool
• Shop vacuum
• Compressed air blow gun
• Flashlight
• Magnetic pickup tool
• Fender cover

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs - Qty: 6
• Upper intake manifold (plenum) gasket set - Qty: 1
• Throttle body gasket - Qty: 1
• Dielectric grease - Qty: 1

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📋 Before You Begin

• Park on level ground, set the parking brake, and open the hood.
• Let the engine cool fully (at least 1 hour after driving).
• Use a 10mm socket to disconnect the negative battery cable and tuck it aside.
• Have clean rags ready to cover the intake openings once the plenum comes off.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Pull up on the plastic engine cover to release the grommets, or remove fasteners if equipped using a 10mm socket.
• Set it aside where it won’t get stepped on.

Step 2: Remove the air intake duct (to reach the plenum area)

• Loosen the hose clamps with a flathead screwdriver.
• Unplug the intake sensor connector(s) by lifting the lock tab with a pick tool if needed.
• Remove the duct and place it aside.
• Tip: Don’t pull on wires—pull on connectors.

Step 3: Remove the front bank ignition coils (front 3 plugs)

• One cylinder at a time, unplug the coil connector (use a pick tool gently on the lock tab).
• Remove the coil hold-down bolt using a 10mm socket.
• Twist the coil slightly and pull it straight up.
• Ignition coil: the pencil-shaped part on top of the plug.

Step 4: Remove the front bank spark plugs

• Blow out the spark plug wells using compressed air blow gun (or vacuum with a shop vacuum) so dirt can’t fall into the engine.
• Remove each plug using a 5/8" spark plug socket, wobble extension (3/8" drive), and 3/8" drive ratchet.
• Install the new plug by hand first using the spark plug socket and extension (no ratchet at first) to avoid cross-threading.
• Tighten with a 3/8" drive torque wrench: Torque to 25 N·m (18 ft-lbs).
• Tip: If it doesn’t thread easily, back out and restart.

Step 5: Reinstall the front bank coils

• Apply a tiny smear of dielectric grease inside each coil boot.
• Push the coil straight down until it seats on the plug.
• Install the coil bolt with a 10mm socket, then tighten with a 1/4" drive torque wrench: Torque to 8 N·m (71 in-lbs).
• Plug the connectors back in until they click.

Step 6: Remove the throttle body from the plenum (access for rear bank)

• Unplug the throttle body electrical connector.
• Remove the throttle body mounting bolts using a 10mm socket.
• Carefully move the throttle body aside. Do not pry on the sealing surface.
• Replace the gasket later with a new throttle body gasket.
• Throttle body: where the intake hose meets the engine.

Step 7: Remove the upper intake manifold (plenum)

• Label and disconnect vacuum/EVAP hoses using pliers as needed for spring clamps.
• Unplug any connectors attached to the plenum area (use a flashlight to see locking tabs).
• Remove plenum bolts using a 12mm socket and 3/8" drive ratchet.
• Lift the plenum straight up. If it sticks, wiggle gently—do not force.
• Immediately cover the intake ports with clean rags.
• Reinstall later: Torque plenum bolts to 18 N·m (13 ft-lbs).

Step 8: Remove the rear bank coils

• With the plenum off, unplug each rear coil connector.
• Remove the coil bolts using a 10mm socket.
• Pull each coil straight up and set aside in order.

Step 9: Replace the rear bank spark plugs

• Blow out each spark plug well using the compressed air blow gun.
• Remove the plugs using a 5/8" spark plug socket, swivel/universal joint (3/8" drive), and 3/8" drive ratchet.
• Start the new plugs by hand first.
• Tighten with a 3/8" drive torque wrench: Torque to 25 N·m (18 ft-lbs).
• Tip: New iridium plugs are pre-gapped—don’t bend the tip.

Step 10: Reinstall the rear bank coils

• Add a small amount of dielectric grease inside each coil boot.
• Install coils and tighten bolts with a 1/4" drive torque wrench: Torque to 8 N·m (71 in-lbs).
• Reconnect coil connectors until they click.

Step 11: Install new gaskets and reinstall the plenum

• Remove the old plenum gasket(s) using a pick tool.
• Clean the sealing surfaces with a lint-free rag (do not gouge metal).
• Install the new upper intake manifold (plenum) gasket set.
• Set the plenum in place and hand-start all bolts.
• Tighten evenly with a 3/8" drive torque wrench: Torque to 18 N·m (13 ft-lbs).
• Reconnect all hoses and connectors you labeled.

Step 12: Reinstall the throttle body and intake duct

• Install a new throttle body gasket.
• Bolt the throttle body on using a 10mm socket, then tighten: Torque to 10 N·m (89 in-lbs).
• Reconnect the throttle body connector.
• Reinstall the intake duct and tighten clamps with a flathead screwdriver.
• Reinstall the engine cover.

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✅ After Repair

• Reconnect the negative battery cable using a 10mm socket.
• Start the engine and let it idle for 2–3 minutes. A brief rough idle can happen while it relearns.
• Listen for hissing (vacuum leak) around the plenum/throttle body area.
• If the check engine light turns on, scan for codes and re-check coil connectors and any unplugged sensors.
• Do a short test drive, then recheck for any loose clamps or fuel/vacuum smells.

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💰 DIY vs Shop Cost

Shop Cost: $450–$850 (parts + labor)

DIY Cost: $90–$220 (parts only)

You Save: $360–$630 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2.5–4.5 hours.

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