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EJ20G Coil Pack Conversion Mod.

#1 User is offline   Reuben 

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Posted 03 September 2013 - 11:53 AM

Hokay, So I've been getting asked to write this one up for a while. "Halp, halp. my stupid coils are fucking out AGAIN on my BC, I hate them and want a simpler solution" Easy, there are two ways you can go about this. Coil pack conversion, or later model ignitor-on-coil-on-plug conversion.

The way I will cover in this thread is the 'Coil pack' mod, that is, the twin coil pack you see on V3's and 4's, and most N/A's from about 93-98. In fact, the PEREFECT donor car for this mod is the 95-96 250-Turd, the BG9A in other words. These cars share the same coil pack as many many other sibies, so it's damn easy to find a replacement, and it happens to be the same coil pack as on V3/4 WRX's and STi's, so we know it's good for turbo duty. The reason it's perfect is the lead length, they allow it to be mounted in a convenient place on the 20G manifold, nice and tidy, and with minimal fuss. The spark plug end of the leads also is from a 20G generation. Yes it's the later generation, so they are a factory fit for the wrx 20G's, but they can be modified very easily to be a perfect fit in the legacy 20G's also. bingo.

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Once you have attained a coil pack and leads, and it doesn't have to be 250T leads, you can get leads of your ideal length off the shelf at any repco if you want, you can commence. The way I have done it, you do not need an ignitor at all, I use the factory ignitor, and just send it's signal to the coil pack, instead of the individual coils. Now, the 20G's, both legacy and 20G run 4 signal wires from the ECU to the ignitor, and the ignitor sends 4 signals out to the coils. This mod has only 2 coils, so you need to join 2 signal wires into one, for each coil. This isn't ideal, as the ignitors output will get fed back into the ignitor itself. Over time this hasn't proven a problem.... yet.... but who knows if it will eventually kill the factory ignitor, or not. I haven't thought that far ahead, and if you were worried, i'm sure a diode could solve that issue.

Now, the nitty gritty, and the part I don't have pics for. The two signal wires per each coil that get wired into the coil pack. it's simple, the forward coil deals with cyls 1 and 2 (the forward two cylinders), and the rear coil, deals with cyls 3 and 4 (the rear cyls). Which coil this is depends on which way you orientate your coil pack, so it's going to be different for each person. If you get it wrong, the car wont run, if you get it right, it will, so it's an easy process of elimination. Where the engine loom connects to the body loom, by the battery, there's a plug with 4 signal wires, and 4 coil power wires and a bunch of other sensor wires. Pick one power wire, tap into it, and send it to the middle pin on the coil pack. That's that done. now find the signal wires fro cyl 1, and cyl 2. you can do this with a multi meter, once you have the old coils out, and the coil plugs at easy access. Just check continuity till you find the right ones. Now join these two wires together, and run another wire from both of them up to the forward coil. Do the same with the rear two signal wires, and run them up to the rear coil on the coil pack. Bam. that fucking easy. I will be getting pictures of this, and wire colours for you in due time, to make it even easier.

A relevant pic from beasts twin turbo loom converted to coil pack:
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Once the coil pack is wired up, secure it in place, it does not need to ground, so my test example in mitches car is actually only ziptied in place, but you can make brackets etc. Also, since you have the coils out, CHANGE YOUR DAMN PLUGS. this is usally the ACTUAL culprit in any miss behaving spark issue, since most people forget they are a sevicable part, not a life long part! standard nickel/copper plugs ($5-8) last 10,000K on wasted spark, iridiums 30-50,000k's ($15-25), and platinums 80-100,000k ($20-30).


Foot note, I wired up beasts differently. Beast did not have a factory ignitor, since he started life with ignitor-on-coil-on-plug, so I had to add one in. I did the same join trick, but at the ECU, but i joined cyl 2 into cyl 1's wire, then used cyl 2's old wire, and joined both 3 and 4 into it, so that at the engine loom end, I had only signal 1, and signal 2 wires, just like, and even the same colour, as on a factory coil packed impreza. only extra step was instead of sending those wires to the coil pack, i sent them to the ignitor, then from the ignitor to the coil pack. the middle pin on the ignitor is just a ground. If you want to use an ignitor to match the coil pack, rather than keeping the factory one matched to the ECU, this is how you would do it.

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<Shale>: Blighter doesn't really have an accelerator pedal, it's more just a loudness pedal. You can change volume, but you won't go any faster.


<mjlqtown>: (Southern US accent) I'v excised the demon! This car is now clear!


<Reuben>: I feel like when you stomp the throttle in Blighter, it's like you've startled an old man!
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#2 User is offline   Leufkax 

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Posted 03 September 2013 - 10:32 PM

Very detailed, thanks
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#3 User is offline   DacerX 

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Posted 03 September 2013 - 10:49 PM

Ya thanks for that
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#4 User is offline   Decimate 

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Posted 06 September 2013 - 11:17 PM

Awesome thanks dude ill look forward to butchering my loom asap
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#5 User is offline   Decimate 

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Posted 07 September 2013 - 4:38 AM

One question:

The two wires that go to each old coil plug, do you join these together? i.e. essentially making one signal wire for each old coil, then run this new signal wire along with its matching wire form its opposite cylinder to the new single coil? Or do you only use one of the signal wires going to each of the old coils then join that up with the correlating wire from its opposite cylinder?

Hopefully that made sense I'll draw a picture if it confused anyone.....
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#6 User is offline   Reuben 

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Posted 07 September 2013 - 12:54 PM

Kinda. You need only the signal wire from the igniter to get to the coil pack. The other wires on the old coils are rendered redundant. Get your multimeter out and simply make sure you have continuity from igniter to coil pack.
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<Shale>: Blighter doesn't really have an accelerator pedal, it's more just a loudness pedal. You can change volume, but you won't go any faster.


<mjlqtown>: (Southern US accent) I'v excised the demon! This car is now clear!


<Reuben>: I feel like when you stomp the throttle in Blighter, it's like you've startled an old man!
0

#7 User is offline   vadzter 

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Posted 08 September 2013 - 10:57 AM

 Decimate, on 07 September 2013 - 4:38 AM, said:

One question:

The two wires that go to each old coil plug, do you join these together? i.e. essentially making one signal wire for each old coil, then run this new signal wire along with its matching wire form its opposite cylinder to the new single coil? Or do you only use one of the signal wires going to each of the old coils then join that up with the correlating wire from its opposite cylinder?

Hopefully that made sense I'll draw a picture if it confused anyone.....


from my understanding, every coil has 2 wires. correct. now of those two wires one is a common power and thats the yellow with red stripe wire. the other is your signal. cyl 1 - red with green stripe, cyl 2 - white with red stripe, cyl 3 - blue, cyl 4 - mint green. you grab any one of the power wires off any coil and that goes to the middle pin and the 2 signal wires you eventually get from joining cylinders 1&2 and cylinders 3&4 go to the other pins on the coilpack.

correct me if im wrong reuben
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#8 User is offline   Reuben 

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Posted 08 September 2013 - 12:56 PM

Spot on cap'n
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<Shale>: Blighter doesn't really have an accelerator pedal, it's more just a loudness pedal. You can change volume, but you won't go any faster.


<mjlqtown>: (Southern US accent) I'v excised the demon! This car is now clear!


<Reuben>: I feel like when you stomp the throttle in Blighter, it's like you've startled an old man!
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#9 User is offline   Decimate 

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Posted 09 September 2013 - 4:09 AM

You're both awesome. Too easy
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#10 User is offline   Oscar 

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Posted 08 December 2013 - 10:38 AM

I was under the impression that because the dwell angles are different between the two ignition types, that this a pretty shit upgrade.

Pull your handbrake just enough so the light comes on. That sends the ECU into full race mode.

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#11 User is offline   Reuben 

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Posted 09 December 2013 - 12:09 AM

Works fine. Post dwell times if you're concerned.
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<Shale>: Blighter doesn't really have an accelerator pedal, it's more just a loudness pedal. You can change volume, but you won't go any faster.


<mjlqtown>: (Southern US accent) I'v excised the demon! This car is now clear!


<Reuben>: I feel like when you stomp the throttle in Blighter, it's like you've startled an old man!
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#12 User is offline   boostin 

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Posted 09 December 2013 - 12:25 AM

I'm not sold on this conversion either as I had a lot of issues with starting. I'm a late model coil-on-plug fan. If you do go with the coil and leads option, make sure you use a coil from a turbo, and not a NA.
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6 stars, 6 cylinder and 6 speed. 666. It's the devil car!!
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#13 User is offline   DacerX 

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Posted 09 December 2013 - 12:30 AM

 boostin, on 09 December 2013 - 12:25 AM, said:

I'm not sold on this conversion either as I had a lot of issues with starting. I'm a late model coil-on-plug fan. If you do go with the coil and leads option, make sure you use a coil from a turbo, and not a NA.


I have driven cars with the mod and i think that it runs quite well
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#14 User is offline   Reuben 

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Posted 09 December 2013 - 2:58 AM

Rusty has a warm start issue if the cars been sitting for more than half an hour, but it was pre existing, coil pack mod did nothing to improve or worsen it. Slow starts can be caused by other things.
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<Shale>: Blighter doesn't really have an accelerator pedal, it's more just a loudness pedal. You can change volume, but you won't go any faster.


<mjlqtown>: (Southern US accent) I'v excised the demon! This car is now clear!


<Reuben>: I feel like when you stomp the throttle in Blighter, it's like you've startled an old man!
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#15 User is offline   boostin 

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Posted 09 December 2013 - 7:22 AM

 DacerX, on 09 December 2013 - 12:30 AM, said:

 boostin, on 09 December 2013 - 12:25 AM, said:

I'm not sold on this conversion either as I had a lot of issues with starting. I'm a late model coil-on-plug fan. If you do go with the coil and leads option, make sure you use a coil from a turbo, and not a NA.


I have driven cars with the mod and i think that it runs quite well


I don't doubt it either. Just posting my experience with the mod.
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6 stars, 6 cylinder and 6 speed. 666. It's the devil car!!
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#16 User is offline   Sammy 

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Posted 10 December 2013 - 8:30 AM

Cheers for the info! Have saved to favorites for further down the line. What do you guys think the better option is the coil pack or the ignitor ontop coils ?
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#17 User is offline   boostin 

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Posted 10 December 2013 - 9:00 AM

I prefer COP. Less to go wrong, and less frequent plug changes.
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6 stars, 6 cylinder and 6 speed. 666. It's the devil car!!
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#18 User is offline   Damo 

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Posted 10 December 2013 - 9:10 AM

I'm A of COP conversion as i found it easier to do by that's only my opinion
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#19 User is offline   DacerX 

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Posted 10 December 2013 - 9:59 AM

ive used both before and honestly about as easy as each other. I just found that COP was more accessibly parts wise where i am
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#20 User is offline   codyjesen 

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Posted 05 February 2014 - 10:03 PM

So with the power wires off each coil I do nothing with apart from one of them, which goes to the new coil pack, is that right?
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