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Old 01-24-2019, 08:16 PM   #1
JimmyMelbs
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Default Wasted spark questions

Hi guys,
I have a 89 740t wagon which has been converted to lh2.4 and need some assistance

I've installed the wasted spark board in my ez, I have it ready to hook up to a 960 ignition module and Bosch 2x2 coils.

I just need help figuring out what to do with existing coil and power stage in the engine bay.
I like being tidy so if I don't need them can I disconnected the existing coil and ignitor?

Can someone who has more information on this than me please shed some light here.

Obviously I still need a tach output.

Thanks
James
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Old 01-25-2019, 06:01 AM   #2
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Quote:
Originally Posted by JimmyMelbs View Post

I just need help figuring out what to do with existing coil and power stage in the engine bay.
I like being tidy so if I don't need them can I disconnected the existing coil and ignitor?
Yes.

You can probably use the tach output of your new power stage (depending on model).
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Old 01-25-2019, 07:14 AM   #3
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According to the wasted spark thread unless running the Miata ignitor with built in ignitor you need the old coil or a 'dummy coil' with an opened relay for tacho .
I'd prefer to do away with old power stage / ignitor and old coil.
Can I do this and if so where do I put the old wiring ?
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Old 01-25-2019, 07:26 AM   #4
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I left the stock ignitor in place since it's already buried out of sight.

Currently my coil is unplugged but still in the bay. Also, not really in the way.

I'm using a dummy relay for my tach signal just fine, followed the many diagrams in the thread. I didn't gut it as the terminals you use aren't the ones connected to the magnet, hence no buzzing.

Once you're confident with your setup, just unplug and tuck the wires away.
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Old 01-25-2019, 01:56 PM   #5
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Originally Posted by nitroboie View Post
I left the stock ignitor in place since it's already buried out of sight.

Currently my coil is unplugged but still in the bay. Also, not really in the way.

I'm using a dummy relay for my tach signal just fine, followed the many diagrams in the thread. I didn't gut it as the terminals you use aren't the ones connected to the magnet, hence no buzzing.

Once you're confident with your setup, just unplug and tuck the wires away.
+1, dummy coil where the tach used to be. Tempted to attach it to the cluster under the dash.

Alfa/Bosch 2 channel powerstage for the Bosch 2x2 coil, stock one left in place for the tach.

Been running WS since 2011, apart from some software issues on the very early stuff it has been very stable. BTI board, Bosch coil, good stuff. Do use the right plugs - ran plugs without resistor and that wreaked havoc with stuff, interference and stuff. Still planning to remove the old spark dizzy. Funny looks at the inspection tho.
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Old 01-25-2019, 02:28 PM   #6
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Originally Posted by JW240 View Post
+1, dummy coil where the tach used to be. Tempted to attach it to the cluster under the dash.

Alfa/Bosch 2 channel powerstage for the Bosch 2x2 coil, stock one left in place for the tach.

Been running WS since 2011, apart from some software issues on the very early stuff it has been very stable. BTI board, Bosch coil, good stuff. Do use the right plugs - ran plugs without resistor and that wreaked havoc with stuff, interference and stuff. Still planning to remove the old spark dizzy. Funny looks at the inspection tho.
Oh, really? Run resistor plugs, even with suppressor core wires?
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Old 01-25-2019, 02:53 PM   #7
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Once you're confident with your setup, just unplug and tuck the wires away.
Same advice I gave him. Remove as much or as little as you want, only after your setup is running.
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Old 01-25-2019, 03:41 PM   #8
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Thanks for the feedback guys.
Did you reuse wiring from old power stage to hook the new one up or take power and ground from elsewhere?
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Old 01-25-2019, 04:28 PM   #9
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Thanks for the feedback guys.
Did you reuse wiring from old power stage to hook the new one up or take power and ground from elsewhere?
I pulled power and ground from factory igniter wiring, so I could mount it on factory heat sink.
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Old 01-25-2019, 05:08 PM   #10
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Originally Posted by soclosenotnear View Post
I pulled power and ground from factory igniter wiring, so I could mount it on factory heat sink.
Thanks Mate really appreciate it
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Old 01-25-2019, 07:32 PM   #11
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Quote:
Originally Posted by JimmyMelbs View Post
Thanks for the feedback guys.
Did you reuse wiring from old power stage to hook the new one up or take power and ground from elsewhere?
I left the stock wiring in place and created my own harness. I used a male connector to plug into the stock blue power wire that connects to the coil. I ground directly on the valve cover. My powerstage is mounted on the valve cover using the BTI bracket.
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Old 01-25-2019, 11:46 PM   #12
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Originally Posted by nitroboie View Post
I left the stock wiring in place and created my own harness. I used a male connector to plug into the stock blue power wire that connects to the coil. I ground directly on the valve cover. My powerstage is mounted on the valve cover using the BTI bracket.
I think I've seen your build somewhere.
I'm mounting my coil like duder did in the location the 240 distributor would sit as there's a hole there for a bracket. I've pulled old ignitor off heatsink and attached the new 960 one.
Now to cut into existing power and ground wires from old connector and pin up the new one along with the wires from the board for the coils and I should be good.
Thanks !
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Old 01-26-2019, 07:21 AM   #13
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Originally Posted by Tfrasca View Post
Oh, really? Run resistor plugs, even with suppressor core wires?
I'm running 500 Ohm/m leads (stainless steel wound ferrite core ishv stuff), less suppression than the usual leads. Denso plugs.
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Old 01-28-2019, 08:03 PM   #14
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Okay all wired up ready to go.
Cut the power and ground wire from the original power stage connector and repinned ground to centre of 2x2 coil and power to pin 4 I think it was on new connector.
Will this work?
Still buttoning everything else up before first start.
I hope doing this will maintain tach function?
Is the old coil still getting power from the battery now or since i pulled power and ground from connector would this affect it?
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Old 01-31-2019, 07:08 PM   #15
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I see some of you guys are unplugging your coil wire.... BE CAREFUL DOING THIS!!! My plastic connector was broken off of mine, I had left mine unplugged and it had worked its way against the strut tower and grounded. There is no fuse to blow. (atleast mine didn't have one) It cooked all of the insulation off the coil wire and would have made it all the way back to my ignition switch if I had not shut if off when I did. I managed to dig out all the cooked wire, I didn't need it anyways and patch up other wire it damaged. I got pretty lucky that my entire car didn't go up. It's pretty easy to make that dummy coil from an old relay. If you don't do that, then cover the ends of those really well. Don't be a dummy like me

Also for some reason I had to leave in my old ignition module in place for my tach signal. I used the J702t ignitor.
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Old 01-31-2019, 09:00 PM   #16
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I also had to leave my old module in place when I used the j702 miata one...I figured mine was a dud from the junkyard....

Using the j702 I have to keep the wire going to the coil connected along with the old module dangling down next to the battery to retain my tach function. My brother just used the red/white wire going to the old module for his tach. I didnt get so lucky
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Old 02-01-2019, 04:29 AM   #17
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Thanks for the replies.
I'm using the Bosch ignitor .
Do I just unplug the coil wire and wire it to the new connector ? Ground to battery - or chassis?
Where do I plug the relay in?
Lastly I've upgraded to an efan. I need switched 12v for this I was going to run off the coil.
Since I'm taking the power lead off that, where else can I get switched 12v from engine bay or do I need to wire it up to something in the cabin?
Thanks everyone!
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Old 02-01-2019, 12:37 PM   #18
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The first (and arguably easier) method works if you have left the stock power stage and wiring intact. Simply move any wires currently connected to the stock coil's two spade terminals to the "85" and "86" terminals of an automotive relay. To keep the relay from clicking you should open the body of the relay and remove the contactor assembly.


I copied and pasted from this: https://forums.turbobricks.com/showthread.php?t=246170
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Old 02-01-2019, 03:12 PM   #19
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Originally Posted by littlesnides View Post
The first (and arguably easier) method works if you have left the stock power stage and wiring intact. Simply move any wires currently connected to the stock coil's two spade terminals to the "85" and "86" terminals of an automotive relay. To keep the relay from clicking you should open the body of the relay and remove the contactor assembly.
.

I copied and pasted from this: https://forums.turbobricks.com/showthread.php?t=246170

Thanks for that but I have 4 or 5 things connected to my stock coil so I'm not sure what they all are
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Old 02-01-2019, 06:20 PM   #20
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Originally Posted by JW240 View Post
I'm running 500 Ohm/m leads (stainless steel wound ferrite core ishv stuff), less suppression than the usual leads. Denso plugs.
Hi Jan Willem, where did you buy them, do you have a link?
As JW stated before running without problems for 4 years now.
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Old 02-08-2019, 06:29 PM   #21
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So I think I have got it.
Just move ALL wires from the positive side and negative side of old coil to a modified relay.
Splice positive wire into the positive wire before it joins the relay.
Remove old coil completely.
Is this right?
Will a 30amp relay handle all this current?
I've got my Efan switched 12v also into this mix.
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Old 02-09-2019, 03:36 AM   #22
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I will check on my car today to be 100%, but the only 2 wires connected to the
relay coil should be the tacho wire, and the (blue? have to check) power wire from the original power stage.

Your wasted spark wiring is separated from this.

The relay coil just generates a voltage spike so your instrument cluster can "read" the pulses.
You do not have to worry about high currents.
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Old 02-09-2019, 07:13 AM   #23
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Originally Posted by Sjeng View Post
I will check on my car today to be 100%, but the only 2 wires connected to the
relay coil should be the tacho wire, and the (blue? have to check) power wire from the original power stage.

Your wasted spark wiring is separated from this.

The relay coil just generates a voltage spike so your instrument cluster can "read" the pulses.
You do not have to worry about high currents.
Please explain this further.
I have about 6 connectors currently which were wired into my ignition coil.
If I disconnected them won't some things on my car not work?
If wasted spark wiring is seperate, then where do I get switched 12v from in the engine bay?
Please explain with pictures as I don't want to fry anything on first start up , there is a lot of conflicting info out there with no definitive explanation on how to actually wire this up in real life
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Old 02-09-2019, 09:34 AM   #24
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What I did:



Take this blue wire and the white&red tacho wire from the coil and connect them to different ends of the relay coil. Remove stock coil.

In addition: wire up the wasted spark like explained here:



Quote:
Originally Posted by JimmyMelbs View Post
I have about 6 connectors currently which were wired into my ignition coil.
No idea why you would have 6 connectors or what they do, sorry.
Mine did not.
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Old 02-09-2019, 09:21 PM   #25
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In addition: wire up the wasted spark like explained here:





No idea why you would have 6 connectors or what they do, sorry.
Mine did not.
Exactly. Just wire it up per the diagram. The stock coil will no longer be necessary so anything that was plugged into it (2 wires) can be left in place. Same thing with the factory igniter, anything that wasnt used can be left unhooked, in place. Nothing is documented about what do with the extra wiring because there isn't anything to do.

I would carefully follow the known, documented diagram posted above and turn the key.
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