Simple Stock Coil Mod...

As most know, our cars are set up with a system that shuts off the secondary coil under high load so the exhaust plugs dont spark... Its a fuel emissions thing... Well, wouldnt it be nice to have twice the spark under full load? Of course.. The more spark, the more air, the more fuel, the more power... Well I tried splitting the wires from wiring harness leading to the primary coil... and ran the same wires to the secondary coil... No longer do my exhaust plugs shut off under high load... Now, this is just a test.. There are risks.. If the coils draw too much current through the wires, they may fry, or if the computer cant handle sending that much power through one set of wires to 2 coils, well, ure computer may fry... So far, I've driven the car long distance, and hard, and its changed my top end power dramatically with no problems... I used to feel a loss of power under full load but if i let off the throttle, it would actually go faster.. Now, I have all that power back under full load... Anyway, just a thought.. It helped me...

Where did you splice in at? Did you splice the blue + wire from the secondary coil to the blue + wire on the primary coil?

hmm a write up with some pics would be nice to have..please

Please post more information and pictures of your mod, I want to do the same thing with my car.

Im also thinking of installing better coils (like the Blaster SS or similar, since I cant find them in Sweden). I have a second ECU and cables if something should go wrong.

Yah more info please

The ECU shouldn't care. It only sends a small signal to the transformers. The transformers turn it into a 12v signal that fires the coil. So the coils aren't drawing any extra current. Since the ECU is only sending a signal, obviously splitting it wasn't enough to disrupt it, so I see no problems with this set up.

Good call. I've been meaning to try this out for a while, but ... bigger fish to fry. You actually need fuel and air to need a hotter spark ;)

I don't know how much more of a write up you guys want ...

The ECU sends a signal to the transformers. One goes to the primary coil, one to the secondary.

He took the ECU signal to the primary transformer, and spliced it. Then he connected it to the secondary coil's transformer in lieu of the ECU signal.

If you plan on doing this and are running the Turbo engine i'd recommend colder plugs on the exhaust side as they are one heat range hotter than the intake side stock. Probably not the best thing for dentonation to have both sides firing but with colder plugs it may not be too much trouble. I'm sure Nissan had a few reasons to make the secondary coil shut down under high loads.

Well, AFAIK, Nissan only added the secondary plugs as an Emissions thing ... I wonder where the 4 plug ca18et's put the plugs. It does seem a bit strange for nissan to rig them to shut down.

the way they're off kilter from one another, I can see why you would actually want both firing all the time. It would actually help to combat detonation, rather than cause it.

Detonation is pre-ignition with no input from the sparkplugs.

Getting a more complete burn and excavation can keep hot spots from forming in the first place.

If I get time this weekend I might try this, but hopefully i won't have this engine much longer...*crosing fingers* 8)

So which one is the primary coil? I think it's the one with the signal line for the tach? right?
So, you cut the power wire leading to the secondary transformer from the secondary coil, and splice it in-line with the postive primary coil wire leading from the primary transformer to the primary coil? Is this right?

not quite

The primary coil's transformer has 3 wires going to it. On mine it's white/green/black

The green is the tacho signal
the black is ground
and the white is the signal

Knowing Nissan, yours will probably be a different color

What this mod entails:

Clip the signal wire to the secondary coil's transformer. Tape off the ECU side of THAT wire.

Splice the transformer end of the wire into the signal wire for the primary coil transformer.

So now the wiring goes ECU - splice - Primary/secondary coil transformer

Instead of ECU - Primary transformer - coil
- Secondary transformer - coil

The ECU sends a signal to the transformers, but it's not enough juice to fire the coil. The transformer transforms that signal into a strong enough jolt to trigger the coil. What we're interested in is the signal, the trigger. By giving the same trigger signal to both transformers simultaneously, both coils will fire simultaneously.

I was thinking more about this last night, and I remembered something relevant. When I used to work for Harley, we got the first run of the 1200 Sportster Sport (stupid name, but the only Harley that will pull the front tire)

An lo and behold, it had a twin plug head vs. the single plug head of the 1200.

The mechanics explained it was the only way Harley could do it. The motors were all already made, and unfortunately were eating themselves. The compression was way too high, and they couldn't dial it in to keep from detonating. So instead of going back and making all new motors, it was cheaper to redesign the head.

And it worked.

If I get time this weekend I might try this, but hopefully i won't have this engine much longer...*crosing fingers* 8)

Heh, no you won't. And boyo, you're getting something special 8)

Anyone else try this yet with noticable gains?

i ran a wire on my ca20e a few months back from the positive on the primary coil to the positive on the secondary coil (just unscrewed bolt a little wraped wire screwed tight again) all the plugs fire and noticed a small gain little less reluctant past 4000rpm and thus far have not had any probs give it a try took me like 30 seconds.

You just added an additional wire and connected it to both positive terminals on each coil? So you have a total of 3 positive wires between the 2 coils? This works?
May sound like a dumb question.......but how do you know all the plugs are firing all of the time?

well you know that the intake are running all the time
so just leave it at idle and unplug them one by one....see if there is spark

exhaust shuts off after 3 i belive, so rev it up wot 3 with one off and if it's still sparking then you good
or if you want you can buy those pricie thingies that you can just wrap around sent a wire into the cabin, attach it to the electrical display drive reving the car up high and it will give you voltage on the wire...then you can see if it's running or not!

An easier way to tell is just get yourself a timing light and hook it up to a plug wire, then drag the gun into the car with you and go for a drive. The light in the gun will only flash when there is spark present. Get it out on the road and put the boots to her past three grand and if the light stops flashing you've got no spark. Oh yeah make sure the clamp is on one of the exhaust side wires. Took me like half an hour to figure that one out, Duhh. Hope that helps

Yeah.....I was thinking a timing gun would work.....but doing it with the hood up, and just reving it past 3000. Will it work that way.....or does it have to be under load.....I don't think my timing light wires are long enough to make it into the drivers seat

It does not have to be under load but you foot does have to be right to the floor (wot position) and I don't know about your car but mine revs up pretty fast and it will go from 3000 to redline in nothing flat leaving you with like one second to see if theres still spark. If your timing gun wont reach your cab you could try tying or taping it to your headlight cover (or hood) facing your seat so you can see it while driving. I just hope it stays there, haha. Its worth a shot. hope that helps.

F*ck it man ... just unhook the primary coil wire (at the coil, no need for a 10,000 volt bullwhip) and take the car for a drive. If it dies around 4,000 RPM, well, odds are your coil isn't firing.

If it winds up OK (it might not be great) ... but as longs as it revs up, I think it's safe to say it works.

You just added an additional wire and connected it to both positive terminals on each coil? So you have a total of 3 positive wires between the 2 coils? This works?
May sound like a dumb question.......but how do you know all the plugs are firing all of the time?
but which wires is the positive coil wires? and what guage wireing do you have to use?

Just went out to test the "secondary coil shutting off above 3500 @ WOT" using Mr. 200's method, and yep by taking the plug boot off the primary coil and driving it....it ran fine until I hit 3500-4000 at WOT, then it just shut off.
I used Shanes method to wire up the secondary coil to run all the time by connecting a short wire to each of the pos terminals on both Blaster SS coils. I left the plug boot off of the primary coil then took it for a drive, and took it to redline at WOT, and the engine didn't shut off like before......so apparantly this works!!
Once I put the plug boot back on the primary coil and took it for a drive I did notice some improvement above 3500 at WOT.
Is wiring it up this way as good as wiring it up before the transistors?

Well, it's hard to say ...

In THEORY, the way you have it wired might not be as good of an idea. You're splitting the signal after it has already been amplified.

The transormers only see a very small signal. Then they convert the signal to 12v, then go to the coil. If you tried to wire your igntion up without the transformers, you'd be lucky if the car will even start.

So by splicing the amplified signal, you're losing some of it. As in the coils are no longer seeing the full amplified signal.

By splicing the signal, instead of the amplified signal, you'll get the full amplification ... maybe.

*lol*

Stupid EE theories.

Problem with the other way (splicing before the transformer), is that the amplification might rely on signal strength, so it is entirely possible that it would do the same thing.

Is there a way to tell if the secondary coil is getting a full 12v at WOT? I guess using a multimeter....but that might be kinda tricky.
Also, I got another thread started....but not many responses....
When I check the volts at the coil terminals.....I'm getting a negative number. I have the blue wire leading from the transistors going to the pos terminal on each coil, and the black/white wire leading from the transistors going to the neg terminal on the coils. I assumed the blue wire was positive when I put these coils on 2 years ago......Any idea if the black/white wires are the positive wires? When I switched the wires around at the coils, I did then get a positive number on the multimeter.....and the car runs perfectly fine both ways. Any ideas?? Does it matter?