🔧 Armada - Spark Plug Replacement

On your Armada’s 5.6L V8, the spark plugs sit under the ignition coils. The front plugs are easy to reach, but the rear plugs typically require removing the upper intake plenum to access them safely.

Difficulty Level: Advanced | Estimated Time: 2.5-4.5 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a fully cool engine to avoid burns and stripped threads.
• ⚠️ Disconnect the negative battery cable if you’ll unplug coils/throttle body wiring (recommended).
• ⚠️ Keep dirt out of the intake: if the plenum comes off, cover the intake ports immediately.
• ⚠️ Do not use anti-seize on Nissan plated spark plug threads unless the plug maker specifically requires it.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• 10mm socket
• 12mm socket
• 3/8" ratchet
• 3/8" torque wrench (10-30 ft-lb range)
• 3/8" extension set (3", 6", 10")
• 5/8" spark plug socket
• Trim clip removal tool
• Needle-nose pliers
• Flathead screwdriver
• Compressed air blow gun
• Shop vacuum
• Painter’s tape and marker
• Magnetic pickup tool
• Flashlight

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (5.6L V8) - Qty: 8
• Upper intake 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 completely (spark plugs thread into aluminum).
• Use painter’s tape and marker to label any hoses/connectors you remove so they go back exactly.
• If disconnecting the battery: use a 10mm socket to remove the negative cable and isolate it.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover and air intake duct

• Remove the plastic engine cover (usually lifts off once its fasteners/clips are released) using a trim clip removal tool as needed.
• Loosen the air duct clamps using a flathead screwdriver.
• Unplug the intake sensor connector(s) carefully (press the lock tab) and move the duct aside.

Step 2: Disconnect the throttle body and related hoses (if removing the plenum)

• Unplug the throttle body electrical connector by hand (do not pull on wires).
• Label and disconnect any small vacuum/EVAP hoses using needle-nose pliers if spring clamps are used.
• If equipped with a resonator/brace in the way, remove it using a 10mm socket or 12mm socket as applicable.

Step 3: Remove the upper intake plenum to access the rear coils

• Before unbolting, use a shop vacuum to clean loose dirt around the plenum and intake area.
• Remove the plenum bolts using a 12mm socket with a 3/8" ratchet and extensions.
• Lift the plenum straight up. If it feels stuck, gently work it loose—do not pry hard on plastic parts.
• Immediately cover the exposed intake ports with clean paper towels. Nothing falls in—ever.
• Remove and discard the old plenum gasket(s). Install new gasket(s) during reassembly.

Step 4: Remove ignition coils (one cylinder at a time)

• Choose one coil to start with so you don’t mix parts up.
• Unplug the coil electrical connector by hand.
• Remove the coil hold-down bolt using a 10mm socket.
• Pull the coil straight up to remove it. (The coil is the “stick” that sits on top of the spark plug.)

Step 5: Remove the spark plug

• Use compressed air blow gun to blow debris out of the spark plug well before loosening the plug.
• Remove the plug using a 5/8" spark plug socket, 3/8" ratchet, and the needed extensions.
• If a plug feels extremely tight, stop and work it gently—forcing it can damage threads.

Step 6: Install the new spark plug

• Verify the new plug matches the old one (reach and seat type). Do not adjust the fine-wire iridium tip.
• Start the plug by hand using the 5/8" spark plug socket and a short extension (no ratchet at first) to prevent cross-threading.
• Tighten with a 3/8" torque wrench: Torque to 18 N·m (13 ft-lb).

Step 7: Reinstall the coil

• Apply a very small amount of dielectric grease inside the coil boot (it helps prevent moisture and makes future removal easier).
• Push the coil straight onto the plug until fully seated.
• Install the coil bolt using a 10mm socket, then tighten with a torque wrench: Torque to 8.7 N·m (77 in-lb).
• Reconnect the coil electrical connector (you should feel it click).

Step 8: Repeat for all 8 spark plugs

• Work methodically: remove one coil and plug, then reinstall before moving to the next.
• Use a flashlight and magnetic pickup tool to avoid losing bolts behind the engine.

Step 9: Reinstall the upper intake plenum and throttle body

• Remove the paper towels from the intake ports (count them to ensure none remain).
• Install the new plenum gasket(s), then set the plenum in place.
• Hand-start all plenum bolts, then tighten evenly with a 12mm socket.
• Reinstall the throttle body with a new gasket and tighten bolts evenly using a 10mm socket: Torque to 9.8 N·m (87 in-lb).
• Reconnect all labeled hoses and electrical connectors.
• Reinstall the intake duct and tighten clamps using a flathead screwdriver.

Step 10: Reconnect the battery (if disconnected)

• Reconnect the negative cable using a 10mm socket and ensure it’s snug.

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✅ After Repair

• Start the engine and let it idle. A slightly rough idle for a short time can happen after intake work.
• Listen for vacuum leaks (hissing). If you hear one, recheck hoses and that the plenum is seated.
• If the idle is unstable after throttle body unplugging, the ECM may need an idle relearn. The most reliable method is a scan tool idle air volume learn (many shops can do this quickly).
• Take a short test drive, then recheck for any warning lights or fuel/air leaks.

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💰 DIY vs Shop Cost

Shop Cost: $550-$950 (parts + labor)

DIY Cost: $90-$220 (parts only)

You Save: $330-$860 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 2.5-4.0 hours.

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🎯 Ready to get started?

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