🔧 86 - Spark Plug Replacement

On your 86, the spark plugs sit deep in the cylinder heads near the frame rails, so access is tight. The job is very doable at home, but it typically requires lifting the engine slightly to create working room.

Difficulty Level: Advanced | Estimated Time: 3-5 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a cold engine to avoid burns and damaged threads.
• ⚠️ Disconnect the negative battery cable before unplugging ignition coils.
• ⚠️ If lifting the engine, support the car securely on jack stands and lift the engine slowly.
• ⚠️ Use a wood block between the jack and oil pan to spread the load.
• ⚠️ Do not pull on wiring—release connectors by their tabs.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Wheel chocks
• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wood block (2x4 or similar)
• 10mm socket
• 12mm socket
• 14mm socket
• 3/8" drive ratchet
• 3/8" drive extensions set
• 3/8" drive wobble extension
• 3/8" drive swivel joint
• 14mm thin-wall spark plug socket (3/8" drive)
• Torque wrench (3/8" drive, inch-lb and ft-lb capable)
• Flat trim clip tool
• Needle-nose pliers
• Flashlight
• Compressed air blow gun
• Dielectric grease applicator (small brush or swab)

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Iridium spark plugs (FA20 correct fitment) - Qty: 4
• Dielectric grease - Qty: 1
• Replacement intake/engine bay plastic clips - Qty: 1 set

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📋 Before You Begin

• Park on level ground, set the parking brake, and place wheel chocks behind the rear wheels.
• Open the hood and let the engine cool fully.
• Disconnect the battery negative terminal using a 10mm socket.
• Set up your floor jack and jack stands so the front of the car can be safely raised when it’s time to lift the engine.
• Take photos before unplugging anything.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the intake pieces for access

• Remove the plastic engine cover (pull upward by hand).
• Loosen intake clamps and remove the snorkel/ducting as needed using a 10mm socket and needle-nose pliers for any hose clamps.
• Remove the air box assembly (typically 10mm socket bolts/clamps).
• Set parts aside in order so reassembly is easy.

Step 2: Remove the battery (passenger-side access)

• Remove the negative cable (already disconnected) and then remove the positive cable using a 10mm socket.
• Remove the battery hold-down bracket using a 10mm socket.
• Lift the battery out carefully and place it somewhere stable.

Step 3: Raise the front of the car and prepare to lift the engine slightly

• Lift the front of the car with a floor jack (rated 3-ton minimum) and support it on jack stands (rated 3-ton minimum).
• Position the floor jack under the engine oil pan with a wood block (2x4 or similar) in between.
• Jack up until the wood block just contacts the oil pan (do not lift yet).

Step 4: Loosen engine mount nuts to create plug access

• From above, locate the left and right engine mount nuts (one each side).
• Loosen (do not remove) the mount nuts using a 14mm socket.
• Slowly raise the engine slightly using the floor jack until you gain working room near the frame rail.
• Lift a little, check hoses, then lift again.

Step 5: Remove the ignition coils (one cylinder at a time)

• Choose one coil to start with so you don’t mix anything up.
• Unplug the coil electrical connector by pressing the tab and pulling straight off.
• Remove the coil retaining bolt using a 10mm socket.
• Twist the coil gently and pull it out.
• Torque on install: Torque to 10 Nm (7 ft-lbs)

Step 6: Clean the spark plug well

• Blow out dirt around the plug hole using compressed air blow gun.
• This helps prevent debris from falling into the cylinder.

Step 7: Remove the spark plug

• Install the 14mm thin-wall spark plug socket (3/8" drive) with a 3/8" drive wobble extension and 3/8" drive ratchet.
• Break the spark plug loose, then spin it out carefully.
• If it feels stuck, stop and work it slowly to avoid thread damage.

Step 8: Install the new spark plug

• Verify the new plug matches the old one (same length and seat style).
• Start threading the new plug by hand using the 14mm thin-wall spark plug socket (3/8" drive) and extension, turning gently to avoid cross-threading.
• Tighten with a torque wrench (3/8" drive, inch-lb and ft-lb capable).
• Torque: Torque to 20 Nm (15 ft-lbs)
• No anti-seize on plated threads.

Step 9: Reinstall the coil

• Apply a very small amount of dielectric grease inside the coil boot using the dielectric grease applicator.
• Push the coil fully onto the plug until it seats.
• Install the coil bolt using a 10mm socket, then tighten to spec.
• Torque: Torque to 10 Nm (7 ft-lbs)
• Reconnect the coil electrical connector until it clicks.

Step 10: Repeat for all 4 cylinders

• Repeat Steps 5–9 for the remaining cylinders.
• As needed, raise or lower the engine slightly with the floor jack to improve access on each side.

Step 11: Lower engine and tighten engine mounts

• Slowly lower the engine fully using the floor jack.
• Tighten the engine mount nuts using a 14mm socket.
• Torque: Torque to 55 Nm (41 ft-lbs)

Step 12: Reassemble intake and battery

• Reinstall the air box and intake ducting using a 10mm socket and needle-nose pliers.
• Reinstall the battery and hold-down using a 10mm socket.
• Reconnect battery positive then battery negative using a 10mm socket.

Step 13: Lower the car

• Remove jack stands (rated 3-ton minimum) and lower the car using the floor jack (rated 3-ton minimum).
• Remove wheel chocks.

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✅ After Repair

• Start the engine and let it idle for 30-60 seconds. It should run smooth.
• Check that no warning lights appear and there’s no misfire (shaking/rough idle).
• Listen for air leaks around the intake you removed.
• Take a short test drive, then recheck that everything you touched is secure.

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💰 DIY vs Shop Cost

Shop Cost: $400-$750 (parts + labor)

DIY Cost: $60-$140 (parts only)

You Save: $340-$610 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 3-5 hours.

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🎯 Ready to get started?

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