callan

Niceee DIY> going to be doing this soon! waiting for my summer job to start paying

GOOD JOB

alcimedes

Just wanted to say another "thanks" for the DIY. Replaced my coils today over my lunch break (advantage of working at home).

No more chirping, starts much better now, and low end power is back to what it should be. Man, what a difference. I did get 62k miles out of the first set, probably can't expect more than that based on what I've been reading here.

Bladecutter

Didn't see the write up earlier, but the steps are sound.

An extra tip:

Feel free to remove the shock tower brace to make removing the air tube between the air box and the throttle body much easier. Doing so also gives you even more room to access the ignition coils. You just need a 12 mm socket to remove the 4 nuts.

More room is always better.

BC.

dozer

iTrader: (3)

myzon26

awesome write up took me no time at all! what did take the time was trying to figure out why when I started it the first time the car went to 1000 rpm then promptly died. as far as i saw at the time the plugs(for some reason they had 3 trailing and one lead plug?idiots) coils and wires(dated 2004) were stock (62200) miles. Then I decided to actually read a little more. I drove it and the computer figured out what was going on within about 20 minutes of driving. Runs like a dream now, again awesome DIY

Rex8y

wao is this easy smh i cant believe i really took it to the dealer last year only if i knew this before shame on me need to spend more time on this forums

pittrx8

iTrader: (1)

Is there a set mileage or time frame to replace coils? I'm having some slow crank issues whether its warm or cold, and after searching think this may be the culprit.

I have replaced the spark plugs already upon recommendation from my local Mazda dealer regarding the slow start, but they also said my battery had a weak charge.

Additionally I am getting lag in all gears below 3-4k, more than I normally had before which is making me rule out the battery as the primary problem. It's a 2005 that just rolled over the 30k mark.

Thank you to everyone on here for the write-ups and informative posts, its saving me a lot of time and frustration by helping to narrow everything down to some known issues!

ASH8

Slow Cranking is either Battery or Starter Motor...weak charge is battery as you were told.

Poor starting or engine firing can be either Spark Plugs or Coils..

IMO 30K your Coils should be replaced..., BUT if Starter / Battery is slow then as I said Coils will not solve this issue.

You "could" have an Alternator issue But more likely Battery then Starter or Both.
I would do Battery first (get a good quality), cheap ones are cheap and do not last.

Houston Sooner

So is white on the old coils a bad sign?? I just hope it helps with the gas mileage

dozer

iTrader: (3)

^thats usually the sign of worn coils, replace them and your spark plugs, clean out your MAF and you should get a few more miles to the gallon

g8ter

iTrader: (1)

Another great DIY, I just finished this up didn't take long at all
Having a MS intake definitely helped cause I had some room to wiggle my hands in there.

monchie

I'm planning to change my ignition coils. I wish i could afford the BHR, but the oem will work just fine. The only thing about the oem coils is you have to change it every 30,000 miles or so, and it depends how long it will last to work normally.

cliffkemp

You do not have to change the coils much at all. If you want the coils to last and the plugs to do well even at high speeds, just close the gap on your plugs to about .042 or so. Closing the gaps about 5-6 thousandths will fix the coil 'issues' with the OEM coils. The coils are decent but, as the plugs wear, if set to the 'OEM' gap, will open slightly with wear and cause the coils to work harder, especially at higher rpms. The carbon build up will make it even harder to fire as it builds up slightly with miles and cause the oem coils to work too hard and wear out.

This is a common myth with OEM coils. Close the gap and problem solved. I do the same thing in my Talon and Laser. They are turbocharged and have about 280 to 310 awhp. Stock gap is .028 to .032. I gap them at .024 to .025 running 18+ psi. The purr like cats. Go above .027 and get on it a few times and it will start to miss on topend.

PeteInLongBeach

This *may* be true regarding the coils, but I would question a couple of related things:Don't you think Mazda experimented with various plug gaps during engine development under objective laboratory conditions and testing? Have you done the same? This is purely anecdotal otherwise...

And, speaking of anecdotes, I have almost 40,000 miles on my original coils, the motor runs & performs like new, so I'm not risking a change in factory-recommended plug gap.

ASH8

There is a recommended Spark Plug gap published by Mazda...I put a thread here somewhere (cant recall the exact details).

However, I don't necessarily disagree with Cliff....I have always had the personal belief that a larger than spec gap in Spark Plugs would but an extra load on Ignition Coils and reduce their life expectancy.

As we know Spark Plug gap will widen with age/use as electrode wears down.

Having said that one must be extremely careful adjusting the gap on any spark plug and not weaken the bridge bar weld.

Frankly, I prefer to renew my Spark Plugs much earlier than suggested or recommended.

MazdaManiac

iTrader: (3)

The plug bar is NOT designed to be bent and cannot be gapped. It will form a pretty nasty hot spot at the point where it bends, which is slightly after the weld.
Rotary plugs used to have fixed gaps (and most still do) and worked just fine to very high outputs for decades.

ASH8

I agree with MM, you are far better off renewing Rotary Plugs than playing with ground gaps.

Mazda's recomendation...

Brand New NGK Spark Plugs
1.15-1.25mm (0.046-0.049in)

Used Maximum GAP
1.50mm (0.059in) Leading Plug
1.40mm (0.055in) Trailing Plug

ken-x8

The box the NGK plugs come in has a pictorial saying to not adjust the gap. So it looks like they also agree with MM.

Ken

PeteInLongBeach

Yeah, I think as long as the plugs are renewed before excessive wear/gap develops, that will help coil life. That said, my plug wear at 30,000 miles was almost negligible - they could have safely gone another 10,000 miles. Still, I think this is a good replacement interval for my purposes...

cliffkemp

my miswording. order a smaller gap on the plugs and not 'physically' change the gap.

My fact still stands that reducing the gap will help the coils last longer by reducing the voltage requirement.

for those that cannot afford a new system or do not want to, this will work and keep the stock coils lasting longer provided the wires are good and the coils are still good.

it is a preference and it works. this is how turbo engine people fix their issues on modded engines running much higher than stock hp. They use a smaller gap and in some cases, also, use a colder plug depending on what is needed. It does work and to each their own.

cliffkemp

I change my plugs out faster than recommended as well. by ordering smaller gapped plugs, my car has 200whp now and has never had that before. I decided to do this to prolong the coils life that I just replaced about 15k miles ago or so.

did the 200whp come from having better topend due to the plugs firing better....could be but, not going to make that claim completely. I will say it runs better above 7200 rpms than it ever did. coils are doing fine and car is running great. personally, I am going to keep getting smaller gapped plugs for the reasons I posted and stand by them.

I will say as in the other post I put, DO NOT physically gap the plugs yourself...I agree with MM on this and I poorly worded my first post. DO buy smaller gapped plugs, if you wish to, as they will work well as I stated for the reason that I stated.

MazdaManiac

iTrader: (3)

And how might one go about that since they don't sell Renesis plugs with a different gap?

TeamRX8

iTrader: (25)

You do not want a smaller gap. I adjust all my plugs and have never had a bar break. Now that doesn't mean you can't bend one back and forth to the extreme over and over again and it won't break, but the usual little bit back and forth getting it right has never caused me any issue.

The factory service manual procedure for testing the OE coils is useless. Use the tool and procedure in this thread instead:

https://www.rx8club.com/showthread.p...77#post4072077


.

cliffkemp

You can go to a site that sells sparkplugs and have them custom made by looking up the dimentions of the plugs and ordering what you need at sparkplugs.com or you can get the denso's that come pre gapped at .043 as I did. If you get the ngk, they will come at around .048 as mazda recommends in their manual.

I still have the manual for my laser and talon and if I gap those copper plugs at .028 to .032 as it and mitsu recommends, it will last about 2k miles before it starts to sputter when boost hits higher than 15lbs. I gapped them at .025 or so and runs great even at 20+psi with stock coils and 8mm wires. I even did it on my old neon with same effects. Whether rotary, forced induction, or NA, this mod works every time.

Ultimately, keeping you plugs changed frequently will help as well but, sometimes, as many of us know, the coils can be somewhat worn even with few miles on them or sometimes, you get a bad coils within a set. it is insurance for new coils that will help them last much, much longer than if you put in plugs gapped at around .004 to .005 more to start.

I am not saying you have to, I am just suggesting it as an alternative if you cannot upgrade or want to make the stock coils last longer. Again, to each their own but, it does work on the principle that a smaller gap requires less voltage given coils are fresh and working properly as well as wires too. It will extent the coils lives by keeping the gap slightly smaller.

Yes, do not try to gap the pregapped plugs...I agree as they are not the same as basic plugs such as the copper plugs and conventional plugs most are used to. I have not ever gapped my old plugs...ever. I just bought plugs that come gapped smaller and made a big difference even after having them in several thousands of miles. No skipping idle, top end is smoothe to 9000+, and my mpg went up about 1 mpg as well. it simply works.

cliffkemp

I have not tested my coils and I do not adjust the gap...so you are saying that you have had no issues adjusting your plugs? I have never tried on the iridium plugs. I have several extras from past changes.

My car runs very good and has never dynoed this high before as I just have a few mods. With the stock gap plugs, even with new or nearly new coils and the same coils on it now, I have had skipping even within a few thousand miles of changing them. After putting in the Denso's that were gapped at .043, it idles better, accels better and have the dyno to show it as well. The highest I got with stock gapped plugs from ngk was 197 in early spring this year when it was much cooler in the morning around 9:30 am around 60 or so degrees. I just had it dynoed a few weeks ago with the temp warmer...around 70 degrees at about 10:30am and it put down 200.1 at around 8600. I am just stating my results as I have never gotten 200whp before and, could be, good tank of gas that day...I do know the idle is much better and topend is smooth. It has never ran this good since I have owned it new back in 2006.

I would not gap them too much smaller than stock but, it does help prolong the coils by keeping the gap around the stock amount or smaller. Since the gap opens as more miles are put on the plugs, starting smaller will help keep the general gap around stock as it wears instead of getting larger than stock for a majority of the time. I do this on my other cars that are turboed and put down way more than stock power and use a step colder plug.

interesting article on testing. I will have to try that whenever my car starts to run funny or what have you. thanks for the link team.