So I went to NAPA to pick up their last two quarts of Royal Purple Racing 21 and special order another two and thought I'd pick up some of the infamous NGK spark plugs while I was at it. I gapped them to about 0.8mm (.030in) as the stock ones were and put them in. After finishing installed, I started up the car and noticed that it did not hang up at 2k rpm as it normally does when it's cold out, but that was only once so I don't know if it was due to the plugs or just coincidence. I haven't put my foot in it yet, so I don't know if it's helped out anything performance-wise, but it's worth it just for the safety aspects.
One question though.. As mentioned in the reply from NGK in another thread, it was recommended that we close the gap a bit more due to the increased boost. Should I get back out there and adjust it to 0.7mm? What're the coincidences of adjusting a spark plug incorrectly?
To replace spark plugs:
1) Using a 10mm socket, remove the bolts on the black engine cover with "Mazdaspeed" logo on it then remove cover.
2) Also using 10mm socket, remove the two bolts on the front side of the ignition coils.
3) One at a time, GENTLY pull spark plug wires out of holes by grabbing their base (be careful, engine may be hot) and pulling directly up. You may need to move the ignition coils out of the way a bit to get to some of them. The two inside spark plug wires are directly attached to the ignition coil, so do those at the same time.
4) Grab a 16mm deep socket with an extension and look down into the uncovered holes. You'll see the end of the spark plug. Just put the socket in there gently and unscrew the spark plugs for a while. I didn't have any other tools so I just kept unscrewing until it felt loose inside there. Remove the socket and if the spark plug is still in the hole, grab the spark plug wire from the left cylinder and put it in the hole deep enough so it grabs on to the plug. Then pull it out.
5) After all plugs are out, check the plugs with a gapper, found at your local auto part store. My plugs were gapped at 0.8mm. Check yours to be sure they're the same.
6) Using the gapper, check the new plug's gap and if neccessary, bend the top of the plug until the gap is set correctly. This may take some time, or it may not.
7) After plugs are gapped correctly, one by one, begin reinstallation. To do this, I again used the left spark plug wire and pushed the plug into it enough for it to hold it safely while putting it back down into the hole. Once it's in the hole, screw it a bit with the wire attached and then pull the wire off. The plug should still be in the hole.
8) Using your 16mm socket again, tighten the spark plugs as tight as you can get them without stripping the plug's thread.
9) Put wires back into the holes again being careful not to put too much stress on them. They can and will break if enough stress is applied to them.
10) Bolt ignition coils back into place along with engine cover, if desired.
11) Start car and hope you don't blow up.
One question though.. As mentioned in the reply from NGK in another thread, it was recommended that we close the gap a bit more due to the increased boost. Should I get back out there and adjust it to 0.7mm? What're the coincidences of adjusting a spark plug incorrectly?
To replace spark plugs:
1) Using a 10mm socket, remove the bolts on the black engine cover with "Mazdaspeed" logo on it then remove cover.
2) Also using 10mm socket, remove the two bolts on the front side of the ignition coils.
3) One at a time, GENTLY pull spark plug wires out of holes by grabbing their base (be careful, engine may be hot) and pulling directly up. You may need to move the ignition coils out of the way a bit to get to some of them. The two inside spark plug wires are directly attached to the ignition coil, so do those at the same time.
4) Grab a 16mm deep socket with an extension and look down into the uncovered holes. You'll see the end of the spark plug. Just put the socket in there gently and unscrew the spark plugs for a while. I didn't have any other tools so I just kept unscrewing until it felt loose inside there. Remove the socket and if the spark plug is still in the hole, grab the spark plug wire from the left cylinder and put it in the hole deep enough so it grabs on to the plug. Then pull it out.
5) After all plugs are out, check the plugs with a gapper, found at your local auto part store. My plugs were gapped at 0.8mm. Check yours to be sure they're the same.
6) Using the gapper, check the new plug's gap and if neccessary, bend the top of the plug until the gap is set correctly. This may take some time, or it may not.
7) After plugs are gapped correctly, one by one, begin reinstallation. To do this, I again used the left spark plug wire and pushed the plug into it enough for it to hold it safely while putting it back down into the hole. Once it's in the hole, screw it a bit with the wire attached and then pull the wire off. The plug should still be in the hole.
8) Using your 16mm socket again, tighten the spark plugs as tight as you can get them without stripping the plug's thread.
9) Put wires back into the holes again being careful not to put too much stress on them. They can and will break if enough stress is applied to them.
10) Bolt ignition coils back into place along with engine cover, if desired.
11) Start car and hope you don't blow up.
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