How do you replace a spark plug on a 2001 Mazda millenia s?

Answer 1

this is a big job. remove plastic "miller cycle" cover, disconnect throttle cable all the way past the firewall, and move it out of the way. pull the front intercooler. the spring clamps on the black silicone connector are tricky, i always replace them with the screw on hose clamps. now you will see the left(front) bank coils. each coil is held on by 2 8mm wrench screws, which also have a Phillips head, but if they have never been off before, use a socket. i prefer 6 pt sockets, i have thrown out all the 12 pt ones. the connector to each coil is really cranky, what i do is push down on the release tab, and at the same time GENTLY pry it away from the coil with a flat blade screwdriver. if you are too harsh, you will break off the lock tab, and the connector will not lock back on. after you disconnect the 3 coils, unscrew the mounting screws, and GENTLY pull off the coils. more than likely, there will be oil in the wells. you need to clean the oil out, otherwise, when you pull the plug out, the excess oil drains into the combustion chamber. make sure you get the correct plug. i like ngk 3741, which is the factory plug. the gap is critical, do NOT use iridiums, they are NOT gapped correctly, and don't believe any parts store, you do NOT regap precious metals tipped plugs. .7-.8mm(.028-.032in) is the correct gap. ngk and denso plugs with -11 after the number is WRONG. -11 means the gap is 1.1mm, WAY too big, and you will kill the coils. which cost a couple HUNDRED apiece. the left bank plugs(2-4-6) should take an hour, max. the right(rear) bank(1-3-5) will test your patience.

this is how i do the right bank. first, all those connectors by the egr valve have to be disconnected. some have a clip holding them on to a bracket, i take those off from the bracket. you can label them all, i don't, because the wiring is now bent in a way that they will only go back on one way. disconnect the hoses from the egr valve, and pull the egr valve. some people don't have to pull the valve, i cannot get at the plugs/coils unless i pull the valve. the big nut on the valve is 23mm, an adjustable wrench will work. then there are the 4 solenoids on a bracket right next to the egr valve, unbolt it, and move it out of the way the best you can. underneath is a short hose, that also has to come off. to me, the connector on #5 is near impossible to get at, some people can get at it, i have to pull off the rear intercooler to gain access. however, to pull the rear ic, you gotta pull the battery, and the battery tray, and disconnect the wiring harness. one of the nuts that holds the rear ic on to the intake is hidden behind it, you have to get at it by feel. once you get all that stuff off, you can now get at the coils and plugs. you will need a couple extensions and universals. because of the level of difficulty getting at the rear plugs, if you take the car to a shop, they will not change them, but charge you for it. that's because it takes so long, they give up. that is why so many of these cars have never had the plugs on the rear bank changed. they THINK they were, but they ain't.

i always clean the wells of oil, if you have air, it is easy but really messy. what i do is keep dipping the spark plug socket and wiping off the oil until it is almost gone. then remove the spark plug, and use a long screwdriver and rags to clean it. oil will short out the coils. they are how much? to stop oil in the future, i clean the inside of each well; brake cleaner works very well for this. feel inside the well, you will feel a groove where the valve cover gasket is. use a good silicon seal, and smear it into the groove. remember, it has to be really clean to take. mark each coil, and swap the right bank coils with the left bank. the right bank coils get a lot more heat, and they don't live as long as the left(front) bank. i also chase the threads, and neversieze the plugs. the right bank will take about 4 hours if it is the first time.