Mazda entrenched itself into the roadster niche with the release of the 1990 MX-5 Miata. In 1999 Mazda redesigned the MX-5 Miata, eliminating the pop-up headlights. It 2006, Mazda redesigned the MX-5 Miata again, giving it an even smoother appearance and adding pronounced wheel flares. The 2006 MX-5 came fitted with a 170-horsepower, 2.0-litre four-cylinder engine. Mazda recommends changing the spark plugs in the 2006 MX-5 every 60,000 miles.
Check the gap at the base of all four new spark plugs, using a spark plug gap tool. The 2006 MX-5 requires a spark plug gap from 0.049 and 0.053 inches. Exchange any incorrectly gapped plugs for new ones, as the recommended plugs for the MX-5 are not adjustable.
Remove the upper engine cover by grabbing the passenger's side of the cover and pulling upward until the clip disengages. Lift the passenger's side of the cover up and pull the cover from the MX-5.
Remove the nuts securing the centre joint of the strut tower brace -- the bar spanning the width of the engine compartment -- using a ratchet and socket. Pull the centre joint from the engine compartment.
Unplug the wiring harness from the top of an ignition coil pack, by pressing the locking button and pulling the harness from the coil pack. Remove the coil pack bolt, using a ratchet and socket, and pull the coil pack off the spark plug with a slight twisting motion.
Remove the spark plug, using a ratchet, 3-inch extension and a spark plug socket. Remove the spark plug from the socket and press a new spark plug into the socket. Hand-tighten the spark plug using the spark plug socket and 3-inch extension. Tighten the spark plug to 8 to 10 foot-pounds, using a torque wrench, 3-inch extension and spark plug socket.
Coat the inside of the coil pack's rubber boot with dielectric grease and press it onto the new plug until it clicks into place. Tighten the coil pack-to-engine bolt to 5 to 7 foot-pounds, using a torque wrench and socket. Plug the wiring harness back into the coil pack.
Repeat Steps 4 through 6 until you replace all four spark plugs.
Reinstall the strut tower brace centre joint and tighten its nuts to 12 to 20 foot-pounds, using a toque wrench and a socket.
Set the upper engine cover in place and press downward until the clip snaps into place.