Somebody had asked for me to make a guide for the replacement of the factory coils, since there has been an upgraded part made by Mazda to improve performace under high heat conditions. I got my coils brand new off of eBaY, for $20 each shipped, but that was a rock bottom price from what I've seen. Always replace all 4 at once unless you have no option. The new part number is N3H1-18-100A-9U.

This is a really simple change out, just some obvious observations and hints....
I don't really think there is much risk for shock here, but I would err on the safe side and pull the negative battery terminal....always good to do a PCM reset anyways...

Next, if you haven't already mastered the removal of the airbox, wrestle that bitch out of there after loostening the two clamps that hold on the flexible charge tube.
Unhook all those vaccum lines etc... just get that intake crap out of the way. You don't have to remove the strut tower brace, but you can if you really want the open space to work in.

Notice the 4 coil packs mounted to their own zinc plated bracket on the front driver's side of the engine block. Each coil has its own ignition harness connection and of course its own spark plug wire.

Grab a sharpie marker, and simply label each connector and each plug wire 1-4 left to right etc... now just yank all the connector plugs (squeeze and pull kind)
and carefully twist off each spark plug wire.... be careful because the actual coil has a press fit extender housing with a spring loaded contact in it...sometimes it will want to come off with the plug wire - it's not the end of the world if it does, just letting you know these pieces can seperate. This is also a GREAT time to put on those new Racing Beat Ultra wires! I also re-routed one of my grounding kit wires to one of the screws on the coil bracket while I was there. Debate is still out on whether or not grounding here is the cause for a bit more noise in my car pc system, but I have heard that it is a performance benfit to give your coils a better than factory ground in any case.

Now that all the wires are pulled, simply take your 10mm socket and unbolt each coil and yank em. The coils are the same for trailing and leading, so just plop on and bolt down your 4 new coils as you unbox them. Re-attach all wires that you have labeled 1-4, and re-install your air intake system. Re-connect battery and perform any needed PCM actions for proper reset (search threads for more info). Inspect your old coils...some see bubbling on the bottom, most people see the white spots that look like hard water spots (normal from what I have been told, the bubbling or worse is probably not normal).

The hardest part of this for a first timer is the airbox... you will feel better knowing it is easy once you figure out how to pull the box and put it back in.

-C

 

perfect. Thanks! I've been thinking about this since I have an '04 and the original coils. It was hard to start after aggressive driving this weekend. Thinking the coils may be the culprit.

 

I replaced mine couple K miles ago.

Couldnt be happier. mine was 05 (I still have my old coils around, in case something **** happen ...)

 

1) You don't need to remove the airbox to remove the coils.
2) The coil bracket is not directly grounded to the coils, so adding a ground strap there does not increase coil performance.

 

step-by-step w/ pix would be nice too

 

Thanks Chamberlen greatly appreciated. I orrederd some must do things including coils so if someone hasnt already got to or planning on it ill post pics once i get them.

 

but it helps a lot .

 

was that $20 shipped each coil price a indivual seller or a store seller. Becuase i cant find that price anywhere

 

Since the heat bubbling on the old coils was on the bottom, I figured the new set could use a little help - I put a "goodly dollop" of CPU heat transfer paste between each coil and the bracket.

If it's not needed, it won't hurt, and maybe it'll cool the hottest part a little.

I know.......just ignore me, it's just the way I am.

 

OK cool, I did see the metal eyelet on each coil, but if that's an isolated part, then I suppose the actual ground is the ground wire cluster near the oil filter neck?

I will update the DIY once you confirm...

thanks guys

-C

 

Yea, good luck on $20 per coil, I paid $89 shipped from the guy who has one coil on eBay right now...he had 5 on a dutch auction...I saved one for you guys!
But typically they cost a bit more than that... I just got lucky

 

Berge Mazda in Phoenix sells them for $26 each.

The mounting bosses on the coils are not attached to their internal grounding point.

 

Normally I would, but this one is really pretty straight forward once you see all the coil packs lined up there...

 

I'd recommend a new set of good aftermarket plug wires while you're at it, the OE wires are marginal at best

 

How many miles do you guys do before you need your coils changed?

 

Already mentioned it! Thanks!

This is also a GREAT time to put on those new Racing Beat Ultra wires!

I changed my coils at 44K

 

I did my coil change without removing the airbox ... well actually without removing anything but the coils.

Was tight, but easier having less to put back

 

what is the difference here between

leading

http://www.racingbeat.com/resultset....rtNumber=11548

trailing

http://www.racingbeat.com/resultset....rtNumber=11549


thanks

 

They are entirely different plug designs and heat ranges.
They must be used in their designated positions.

 

I'm changing my coils today! At 63,000 miles. I've been suspecting something isn't putting out, so I decided too also get wires while I'm at it... I actually just looked at some 1 week old installed iridium plugs and they have a brown layering on them... Within a week, I dunno if that's normal...

 

I am gonna be doing a engine decarb, oil change,spark plugs in like two weeks do you guys think it would be a good idea to go ahead and do the coils and cables also? they are the original ones on my 04 mt with 54k on it...the decarb is gonna cost 80. the plugs i got for free(my cousin works at mazda)...so im guessing the coils and cables are gonna be around 230 to 250 shipped... so for the oil change, wires and plugs, coils, and decarb its gonna run me around 350 total......do you guys think i dont need to do some things i mentioned or is there some other maintence i could do while i am at it?

 

Sounds like a good idea to me......I'm gonna do that! It can't hurt as you said, and I work with that all the time, so WTF.

 

What's an engine decarb?

If you get new wires, buy racing beat or somebody's good wires.... if you gotta get Mazda wires there is a brand new set on eBay right now I think for $20 or so.

If you can get new coils off of ebay for around $100 for all 4, then do it, otherwise I would just leave them alone for now. Since you got the plugs for free, why pay full retail price on Mazda factory parts when you can buy aftermarket?

 

ya i dont know about the coils yet but i am getting the rb wires and the decarb is offerd by a local mzda dealership that is supposed to clean the rotors and the intake manifold...any one else heard about this engine decarb

 

what the heck are coils?