2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

are there any ill effects to running without the trailing coils?

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Old Jan 18, 2013 | 07:18 PM
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are there any ill effects to running without the trailing coils?

I just would like to know will there be any negative effects on the engine without trailing spark. Does anyone have any experience with this?
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Old Jan 18, 2013 | 07:33 PM
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Eh, not really... Nothing that will kill an engine if driven reasonably. I wouldn't run it on just leading spark for too long. Get some trailing coils if you need them.

I had my first set-up tuned on only the leading coils. (Due to trailing coil malfunction.)

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Old Jan 18, 2013 | 07:40 PM
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Why would u run without it? Less spark means less burned fuel , that's why they have 2 plugs per rotor.

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Old Jan 18, 2013 | 09:53 PM
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I guess I should've explained more. I have a crane hi-6 cdi box on the leading coil. I have the unit setup to kill the trailing coil when I engaged the two step rev limiter. The issue is when I use the two step trailing coil turns off but doesn't come back on until the car is turn off and then turned back on. So if I launch using this I can only run on the leading coil. I'm using a rtek 2.1 with my setup btw but that shouldn't matter I believe.
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Old Jan 18, 2013 | 09:58 PM
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Originally Posted by hiroichi1515
I guess I should've explained more. I have a crane hi-6 cdi box on the leading coil. I have the unit setup to kill the trailing coil when I engaged the two step rev limiter. The issue is when I use the two step trailing coil turns off but doesn't come back on until the car is turn off and then turned back on. So if I launch using this I can only run on the leading coil. I'm using a rtek 2.1 with my setup btw but that shouldn't matter I believe.
my question still is why kill the trailing spark? Or you didn't have a choice?

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Old Jan 18, 2013 | 10:32 PM
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You can't limit revs without cutting the ignition. If I don't stop the trailing coil the car will continue to rev.
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Old Jan 18, 2013 | 10:49 PM
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Originally Posted by hiroichi1515
You can't limit revs without cutting the ignition. If I don't stop the trailing coil the car will continue to rev.
Aren't you going to lose power by not having trailing spark ?

I would try to see if there's a way to get the trailing coil to turn back on after its cutting off so you'll still be provided with that spark.

I'm not familiar with 2 step or standalone ecus but I'd venture to say theyd incorporate a design that keeps the trailing coil from staying off, it'd just be more logical (imho)for it to turn back on

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Old Jan 18, 2013 | 10:58 PM
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I've tried that route for months. Can't find how to keep it on. I raced a Chevy SSR and left him pretty good on two plugs but I didn't notice any power loss. I was just want input for someone who has ran like this at the track or something.
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Old Jan 18, 2013 | 11:55 PM
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Originally Posted by hiroichi1515
I've tried that route for months. Can't find how to keep it on. I raced a Chevy SSR and left him pretty good on two plugs but I didn't notice any power loss. I was just want input for someone who has ran like this at the track or something.
You'll probably just run more rich, if you had a wideband and egt gauge you could do one run with and one run without and see what kind if difference its making.

You'll need a way to record it though, does the rtek have those capabilities?
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Old Jan 19, 2013 | 12:05 AM
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Originally Posted by wthdidusay82

You'll probably just run more rich, if you had a wideband and egt gauge you could do one run with and one run without and see what kind if difference its making.

You'll need a way to record it though, does the rtek have those capabilities?
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Yes, I can datalog. I don't know why I didn't think about that before. My wideband is down by the ashtray so it's kinda hard to keep and eye on. I will def give it a shot though.
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Old Jan 19, 2013 | 12:29 AM
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Originally Posted by hiroichi1515

Yes, I can datalog. I don't know why I didn't think about that before. My wideband is down by the ashtray so it's kinda hard to keep and eye on. I will def give it a shot though.
Goodluck

I'm eventually going to get rtek 1.x for my car and get 2.x when my car is modded beyond the 1.x

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Old Jan 19, 2013 | 12:45 AM
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The rotary really only NEEDS the leading plugs. The trailing plugs do little in the way of power and driveability and are primarily for emissions cleanup. In fact I have known of people who drove around on a dead trailing coil and did not know it for a long time. I have in fact driven cars like this as well and the only thing you may notice is a very slight change in it's personality during startup and a very slight change in the low rpm torque characteristics when taking off from a stop or on a hill.

In fact a few years ago KD rotary came up with the infamous "anti detonation mod" which they tried to keep secret for a while, promised to help modified turbo rotaries live longer. It was eventually discovered that they were inserting these tiny aluminum dummy plugs on the end of the trailing spark plugs, to fill the holes in the rotor housings, then unplugging the trailing coil and changing the computer tuning a bit.

I wouldn't do it just to be doing it, but if there's a specific reason then it won't hurt the engine as long as you rev it up often enough to displace any extra carbon built up on the trailing edges of the rotor faces. That's really all the trailings do, attempt to clean up the little "pocket" of unburned fuel left at the trailing edge of the rotor face as the combustion chamber narrows and gets "pinched off" as the rotor passes the trailing plug. It's mostly for emissions purposes.
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Old Jan 19, 2013 | 05:45 AM
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Lack of tailing coils will cause a loss of power, been through this many years ago.
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Old Jan 19, 2013 | 07:35 AM
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Originally Posted by RotaryResurrection
The rotary really only NEEDS the leading plugs. The trailing plugs do little in the way of power and driveability and are primarily for emissions cleanup. In fact I have known of people who drove around on a dead trailing coil and did not know it for a long time. I have in fact driven cars like this as well and the only thing you may notice is a very slight change in it's personality during startup and a very slight change in the low rpm torque characteristics when taking off from a stop or on a hill.

In fact a few years ago KD rotary came up with the infamous "anti detonation mod" which they tried to keep secret for a while, promised to help modified turbo rotaries live longer. It was eventually discovered that they were inserting these tiny aluminum dummy plugs on the end of the trailing spark plugs, to fill the holes in the rotor housings, then unplugging the trailing coil and changing the computer tuning a bit.

I wouldn't do it just to be doing it, but if there's a specific reason then it won't hurt the engine as long as you rev it up often enough to displace any extra carbon built up on the trailing edges of the rotor faces. That's really all the trailings do, attempt to clean up the little "pocket" of unburned fuel left at the trailing edge of the rotor face as the combustion chamber narrows and gets "pinched off" as the rotor passes the trailing plug. It's mostly for emissions purposes.
Thanks for your input. This is what I was hoping to hear.
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