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Ignition coil thread

Old 03-18-11, 01:10 AM
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Ignition coil thread

I'm trying to figure out what kind of ignition coils to use. I got some LS1 coils for my rotary miata, and they just flat-out aren't cutting it. The spark can barely be seen on the plug, and it hardly even runs with them. I even tested my megasquirt output signal with an oscilloscope! The coil output just isn't good enough. And I guess that's understandable, rotaries seem like they would need a healthy spark. I don't know if I got a damaged or underpowered set of ls1 coils, but since I have to buy ignition equipment again I want to go all-out this time. I want sparks so big that it startles me. I want a setup that I have to genuinely be afraid of.

So I remembered seeing these coils on a pro drifter's car. He warned me not to fiddle with them or they might kill me. Seems like a good start.

The coils seem like they each have two posts though. So for a rotary you would need at least three, and just leave two posts open? or am I missing something? I'd prefer a setup where I could do completely independent ignition control.

I also saw these bosh units on the Atkins rotary website:

They seem like a pretty standard unit, and they're not too expensive. Those spade connectors look kinda ugly though. Anyone have any experience with these?

Beyond that, I'm not familiar with any aftermarket coil setups. I've used toyota coil-on-plug packs and ls1 coils on four-cylinder cars, and they worked great.

I've seen msd units like this before but I have no idea if they are any good.

every time I read about them, I just see the words 'small block' mentioned about 9000 times.

I can use anything as long as it has a built-in ignitor. Or I guess a separate ignitor would be negotiable, but they'd have to be putting out some awesome sparks for the extra effort.

Or should I just get a set of stock rx7 coil packs? Are the turbo ones better? How do rx8 coil-on-plug packs perform? Those look pretty cool. Recommend the highest voltage, nastiest, could-probably-kill-a-bull-elephant coil packs there are.

Last edited by N3v; 03-18-11 at 01:31 AM.
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Old 03-18-11, 03:11 AM
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RX7 Stock Coil Pack + OKADA Project Plasma Booster is very nice combo and works very well together.

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Old 03-18-11, 04:01 AM
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http://www.034motorsport.com/ignitio...ver-p-277.html
I've heard from some pretty experienced people, these are among the top coils you can get.



Those wasted spark coils look like just relabeled GM v6 coils.
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Old 03-18-11, 05:43 PM
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If you're barely getting any spark with the LS1 coils, something must be wrong. On Miataturbo people use them for 30+ psi turbo pressures.

BTW: Let me know on CR if you decide to part out that exhaust like I messaged.
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Old 03-18-11, 06:06 PM
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You just can't slap on any set of coils and expect them to work correctly. Certain parameters of the ecu needs to be configured to run them properly. The LS1 coils have more fire than the stock FC coils. I've just upgraded to the Yukon coils (D585) which are a major upgrade from the LS1 coils. These are the same coils that are being using to upgrade the stock coils on the Rx8. By the way , the stock Rx8 coils are junk! I'll know how my updrage performs here in a couple days.

What are your ignition settings? LS1 coils like about 5ms charge times.
What's your power goal?
NA or Turbo?


You will need 4 single output coils for direct fire ignition on a 13b. I like direct fire because you have more precise control over timing and negative split for better fuel economy. I'm not to familiar with the megasquirts so I don't know their ignition configurations or capabilities. The top pic has twin outputs and would work in the leading position in a wasted spark set-up (stock Fc and Fd use wasted spark). You would then need to 2 SINGLE output coils for the trailing plugs.
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Old 03-18-11, 06:53 PM
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i just want to reiterate: the stock Rx-8 coils are utter crap!

i've been hearing mostly good things about the LS2 coils used on rotaries though and will probably go that route when the Rx-8 needs coils again. for a long time, i was hell-bent on using the high output coils that BMEP sold, but they're no longer available.
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Old 03-18-11, 08:54 PM
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LS2/Yukon coils since you are already set up for that style of ignition. Otherwise the stock FC system is the strongest.
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Old 03-18-11, 11:40 PM
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to all the people saying that the coils should be fine:

my megasquirt dwell was set properly for the coils, I made sure I had a good signal ground and good power/grounds. After my first failure due to lack of spark I measured the ms output signal with an oscilloscope, and saw that the signal was lasting exactly as long as the dwell setting set it to. I checked it at the end of my harness, to make sure it wasn't dropping off because of noise or harness resistance.

I know that the coils should work (in fact they're even the ones supposedly from a chevy v8 truck which are supposedly better) but they just don't. They don't spark powerfully enough to clean out the plug. It sparked okay for a little while, then the plugs got dirty and I had to meticulously clean them before the spark looked okay. and when I say 'okay,' the spark still only showed up on a timing light barely here and there.

It confirmed my suspicion when I looked at my coil output vs a stock rx7 output the other day. Like I said, I don't know if those coils are bad, but I want to eliminate ignition as a possible source of any problems in the future and overdo the heck out of it.

Last edited by N3v; 03-18-11 at 11:44 PM.
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Old 03-18-11, 11:55 PM
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LS1 coil wires one way
chevy truck coil i assume is a yukon D585 and this wires differently to the LS1,, the plug is mirrored back to front

if you have wired them as LS1,,then there is the problem, right there
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Old 03-18-11, 11:58 PM
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what plugs are you using?
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Old 03-18-11, 11:59 PM
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I took all that stuff into account they spark every time it's just weak.

The wiring is really straightforward, the red wire is positive, the black is ground, gray is signal ground, each variating color are the triggers.

And this is an ignorant question but how do ignition boxes work? like, the coil just wants 12v and ground and a tiny signal. modifying the ignition signal wouldn't help, so what do they do, increase the voltage from 12v? decrease resistance on current draw?

edit: oem spark plugs, leading and trailing

Last edited by N3v; 03-19-11 at 12:03 AM.
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Old 03-19-11, 12:07 AM
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what plugs are you using?
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Old 03-19-11, 12:08 AM
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Originally Posted by diabolical1 View Post
what plugs are you using?
Originally Posted by N3v View Post
edit: oem spark plugs, leading and trailing
.
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Old 03-19-11, 12:51 AM
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sorry. that was just a stupid double post. my computer was acting bitchy and i couldn't load the page to see if my post went through. when it finally loaded, the last post i saw was #8, so i sent it again.

at any rate, if you're sure everything is wired correctly and all parameters are fine, maybe you should try another type of plug. years ago i suddenly started having spark issues and changing the plug type did the trick.
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Old 03-19-11, 12:58 AM
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Originally Posted by N3v View Post
I took all that stuff into account they spark every time it's just weak.

The wiring is really straightforward, the red wire is positive, the black is ground, gray is signal ground, each variating color are the triggers.

And this is an ignorant question but how do ignition boxes work? like, the coil just wants 12v and ground and a tiny signal. modifying the ignition signal wouldn't help, so what do they do, increase the voltage from 12v? decrease resistance on current draw?

edit: oem spark plugs, leading and trailing
did you ground both earths in the coil plug?

there is most definitely something wrong in your wiring or setup,, i hardly think you bought 4 dud coils
and if you have yukons, and is using 5 ms of dwell,, you should be almost set to weld with that spark


is your signal polarity back to front?
easy to get the WRONG impression if you using the oscilloscope with its filters set to start recording off a certain trigger edge
i suggest you try reversing the setting in the software ( and recalibrate timing )
before you spend a cent
And this is an ignorant question but how do ignition boxes work? like, the coil just wants 12v and ground and a tiny signal. modifying the ignition signal wouldn't help, so what do they do, increase the voltage from 12v? decrease resistance on current draw?
what type of ignition box? the micro x box is simply a daughter board of IGBT ignition drivers in a box, the motherboard on the ECU is saved from the heat
you need this sort of thing to drive those dumb bosch HEC 715 coils you pictured above
( or just buy 4 x BIM137 ,, or 1 X 4 way equiv BIM )


you can get step up transformers for 16 and for 24 V for coils and for fuel pumps
but the ones i have at home ( ICE ) are for short use only as they soon crack coils from overheat
( and likely some ignition drivers )

none of these are necessary when you get the parts you have now to work well
i suggest you look closer at the issue,,
spending on bigger and better will amount to still nothing if there is something very basic going wrongs as is

Last edited by bumpstart; 03-19-11 at 01:01 AM.
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Old 03-19-11, 01:30 AM
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Originally Posted by bumpstart View Post
did you ground both earths in the coil plug?

there is most definitely something wrong in your wiring or setup,, i hardly think you bought 4 dud coils
and if you have yukons, and is using 5 ms of dwell,, you should be almost set to weld with that spark


is your signal polarity back to front?
easy to get the WRONG impression if you using the oscilloscope with its filters set to start recording off a certain trigger edge
i suggest you try reversing the setting in the software ( and recalibrate timing )
before you spend a cent
tried this. I've tried pretty much everything. Is there anything I can hook up to a coil that will give me a readout, like how many volts and amps? i think 60,000 volts is too much for my multimeter.
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Old 03-19-11, 01:44 AM
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Is there anything I can hook up to a coil that will give me a readout
your tongue

just checking-
have you tried bridging 12v straight to the coils from battery,,
or tried running the current IG 12v as trigger for a new ignition relay ?
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Old 03-19-11, 02:08 AM
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i mean the only questionable thing in the equation is that I have a shitty battery. I cranked it too many times trying to start the car, and now the voltage drops pretty bad at cranking. I have plenty of overall chassis grounds. I can take the CAS out and spin it and I've verified good 12v+ at the coils are firing.

While pullstarting I could see that the spark wasn't any better though. (creative use of timing light, haha)
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Old 03-19-11, 10:06 AM
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Originally Posted by N3v View Post
i mean the only questionable thing in the equation is that I have a shitty battery. I cranked it too many times trying to start the car, and now the voltage drops pretty bad at cranking. I have plenty of overall chassis grounds. I can take the CAS out and spin it and I've verified good 12v+ at the coils are firing.

While pullstarting I could see that the spark wasn't any better though. (creative use of timing light, haha)
Edit: I tested my coil by holding the plug wire near the body of the car and turning the cas and watching the arc that it made. Then I did the same thing on a stock rx7. my coils were firing every time, but the spark on the rx7 was visibly more intense than mine.
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Old 03-19-11, 05:09 PM
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Originally Posted by N3v View Post
i mean the only questionable thing in the equation is that I have a shitty battery. I cranked it too many times trying to start the car, and now the voltage drops pretty bad at cranking.

What is your cranking voltage droping down too? I had problems with the Ls1s when my voltage droped too low. Can you see the actual cranking voltage on your laptop while cranking? The ls1 coils don't fire well below 11volts and are a bit more power hungry. They don't like weak batterys.

Edit: I ran my 20b with stock Fc trailing coils. I then switched back to the LS1 coils and made more power. No dyno just seat of the pants feeling. Something is wrong with your set-up somewhere.
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Old 03-22-11, 12:28 PM
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Originally Posted by t-von View Post
What is your cranking voltage droping down too? I had problems with the Ls1s when my voltage droped too low. Can you see the actual cranking voltage on your laptop while cranking? The ls1 coils don't fire well below 11volts and are a bit more power hungry. They don't like weak batterys.

Edit: I ran my 20b with stock Fc trailing coils. I then switched back to the LS1 coils and made more power. No dyno just seat of the pants feeling. Something is wrong with your set-up somewhere.
The low voltage could be it. I am also using the stock tiny miata battery. I think I'll replace it with a beefy battery and make a custom tie-down then see what I get
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Old 03-22-11, 01:42 PM
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Originally Posted by papiogxl View Post
http://www.034motorsport.com/ignitio...ver-p-277.html
I've heard from some pretty experienced people, these are among the top coils you can get.



Those wasted spark coils look like just relabeled GM v6 coils.
I'm running 4 of those on my 545 RWHP TII and E85. Direct Fire.
Haven't had any problem so far.
Here is a better source.
http://www.diyautotune.com/catalog/i...oil-p-394.html
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Old 04-13-11, 02:39 PM
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I wanted to report back that switching my battery for an optima red-top did the trick. here's a video I just made. the smoke is just stuff burning off the header. I'm pretty stoked.
[youtube]-oz35TbjX5A[/youtube]
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Old 04-13-11, 05:14 PM
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Thx for reporting back. LS1 coils are a very nice cheap solution for a lot of us. I can't wait to see what my Yukon coils do.


Edit: I see you don't have a 12v supply to the alternator. Your alternator isn't goona turn on and charge without that hooked up.
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Old 04-13-11, 11:25 PM
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it might look a little misleading, but my 12v wire is black. it seems to work fine. on my tuning software, the battery voltage reading jumped up to 13.8v when the car was running.
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