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Miata Spark plugs

Your Miata

Pick your year to see what fits.

There was no 1998 Miata in the US. The NB model started as a 1999.

+0–3 whp (est.)
Easy$40–$1201 hr
All Miata mods

Why do it

Fresh plugs bring back the crisp throttle and power you lose as old plugs wear.

Tools you'll need

Starting out? See our budget tool list.

Parts to buy

Double-check fitment before buying. We may earn a commission when you buy through these links, at no extra cost to you.

Before you start

  • Work on a cold engine.
  • Work on a cold engine.
  • Work on a cold engine.

Steps

  1. Pull the wires

    • Pull the plug wires one at a time, gripping the boot rather than the wire.
    Watch this step (DriveMX5, on an NA/NB) (1:23–1:43)

  2. Swap the plugs

    • Unscrew each old plug. Put a little anti-seize on the new threads, then thread each one in by hand and torque it.
    Watch this step (1:43–5:21)

  3. Refit the wires

    • Add dielectric grease to the boots and push each wire back on until it clicks.
    Watch this step (5:21–6:43)

  4. Remove the old plugs

    • Open the hood, remove the coils and unscrew each old plug.
    Watch this step (Project380, on an NC) (0:51–2:17)

  5. Fit the new plugs

    • Thread each new plug in by hand, torque it and refit the coils.
    Watch this step (2:17–4:41)

  6. Remove the coils

    • Remove the four coil bolts and pull the coils out.
    Watch this step (TurboSource, on a turbo ND) (1:20–1:39)

  7. Pull the plugs and check the gap

    • Unscrew each plug, then check the gap on each new plug.
    Watch this step (1:39–3:15)

  8. Fit the plugs and coils

    • Thread each new plug in by hand and torque it, then refit the coils and their bolts.
    Watch this step (3:15–3:41) Watch the coils go back on (3:41–4:34)

How to know it worked

Did this guide work for you?

Safety first

  • Park on flat ground, set the parking brake and chock the wheels.
  • Never get under a car held up only by a jack. Use jack stands.
  • Let the engine and exhaust cool first.
  • Disconnect the battery before unplugging electrical parts.
  • Wear safety glasses.
  • If something doesn't match your car, stop and ask a shop.

Follow your part's instructions and your service manual's torque specs.