How-To: Dual Coil Mod

[soapdude]

That's crazy... Thanks..

I am ordering an MSD Blaster SS today... What do you mean by bigger plug and coil wires?

[Xano]

That's crazy... Thanks..

I am ordering an MSD Blaster SS today... What do you mean by bigger plug and coil wires?

Plug wires, and coil wires.  Go with a set of 8.5MM or larger wires (you'll need 7 total)

1 for each cylinder, and 1 for the coil to the distributor....stock wires are either 7mm or 8mm wires.  Theres companies that sell 10mm wires, but imo thats overkill.

[soapdude]

Where do I get these wires? Are they made for these cars...? So I shouldn't go NGKs??

[Xano]

Where do I get these wires? Are they made for these cars...? So I shouldn't go NGKs??

NGk's would work too, they have a better core inside the 8mm wires, which makes up for the smaller size.  You'd have to get a set of NGK's made for the V6 model, not the 4cyl though.

The other wires are make to fit, meaning you have to cut them, crimp and solder connectors on, and put the boots on yourself and all that.

with the larger wires, you just get a spool of wire, and boots.

[soapdude]

Gotcha... Thanks!

[soapdude]

I just put NGK Iridiums on my car and a set of NGK wires made for the 300z ($50 bucks cheaper!), and man what a difference!!!

[Lupich]

This sounds like something I'd love to do but is super confusing without pictures.

Can you help me out?

[silver_s13]

Okay since this thread is all about converting your dual(primary/secondary) coil setup to what is what is pretty much considered a "waste spark" type ignition system, lets make this a little bit easier for everyone to understand. The factory coil configuration on your four cylinder 200sx operates by creating a spark for the intake(primary) spark plugs and a separate spark(which is why you have two coils) for the exhaust(secondary) spark plugs. This allows the engine to run at optimal efficiency at low(below 4000) RPMs. to maintain this efficiency at higher RPMs you simply have to feed the secondary coil with the primary coils positive signal. There are a few arguments as to the proper wiring for this but it can be done. Another option to consider that has been totally over looked is to use a GM dual tower coil. These coils do exactly what our other members are trying to achieve but without the meesiness of wiring harness modification.They produce an equal spark from both towers of the coil at the same time through a single feed. This will allow the dual spark to take place exactly like the other method.

The connection to power this wonder of engineering is a simple + and - located at the bottom of the coil. use your imagination and you'll be able to make the required connection without any harness modification. The connector for these coils are small blade type prong that simply slides into to base of the coil(Kinda like a home outlet). It is mounted by two centrally located screws on each side. If someone was able to mount this on a small piece of plywood with prongs fastened to it with some type of threaded post to connect the factory primary coil connector they could mount this coil and isolate it from a short circuit condition at the same time. This in theory will still allow you to run all spark plugs and there corresponding wires as designed from the factory and still allow the dual spark condition you are looking for. The best part of this method is that there is no cutting/splicing of the factory harness so the original equipment could be reinstalled at any time. I apologize for the length of this post but this (to me) would be the easiest method to achieve this. Well what do you guys think? I know it's "outside of the box" but it should work.

[IggyEGuana]

On NICO theres a lot of info about converting the CA18DET ignition system from COP to GM waste spark coils.  In it they say (if using stock ecu instead of standalone) you have to eprom and rewrite the ignition values to be compatible with the coils.

No real point to me sayin this.  Just be aware of the possiblity of this not working.

[silver_s13]

Contacted MSD about this and still waiting for a reply. I'll probably try it anyway and see.

[200sxkitcar]

Jesus, this thread is full of mixed and often off information.

The BLACK/WHITE wire is the positive feed from the fuse block.  The same wire has a splice and feeds both coils.

The BLUE and BLUE/WHITE are the computer-controlled ground sides.

If you are jumpering the black/white wires, you are simply adding another splice.  The black/white wires are already connected.

If you want both intake and exhaust side plugs to fire, you would need to jumper the blue and blue/white wires together.

This information applies to all model years of CA20E and CA18ET per all the FSM manuals that I have.

The S12 does NOT have a waste-spark system, and the dual-coil mod does NOT convert the system to waste spark.  When you jumper the system, it is like running two entirely independent spark systems simultaneously.  There is no waste-spark action.

If you disconnect the coil and transistor assembly completely, you can measure the voltage present at the connector.  You will find with the key in the 'ON' position there will be 12V at the black/white wire's terminal.  Feel free to check this before you do this mod.

If you jumper the blue and blue/white wires, I would do it before the transistors.

I personally don't care too much for this mod, I don't think its particularly necessary or a good idea, but if you want to do it, do so at your own discretion.  Several people have done it without issues.

Once I have some time, I'll put together some pics and diagrams, unsticky this thread, and put the info in a new one and sticky that, to clear up the confusion.  I will also add all the technical reasoning and logic behind these statements.

Please refrain from discussing the V6 motor in this thread, seeing as its aimed at the cursed 8 plugged 4cyl cars  

[alundra]

Nice thread but what about detonation?
Is there any electronic device to test our det sensor?
A multimeter is it sufficent? A computer?

[silver_s13]

The definition of a waste spark ignition system in case there is any confusion according to wikipedia

A wasted spark is when in an ignition system in a four-stroke cycle internal combustion engine spark plugs fire in pairs, on both the exhaust and compression strokes. The extra spark on the exhaust stroke has no effect and is thus "wasted".

Are you saying that both plugs fire at the exact same time?
The contact on the rotor for the intake side is larger then the contact on the exhaust. I assume the intake fires BTDC and the exhaust fires either at TDC or ATDC. If thats wrong then I stand corrected and this would be considered standard system. Otherwise if they are sequential and fire at BTDC and TDC/ATDC it is in fact a waste spark system and only in place to reduce emissions.

[raid_650]

ok so i read thru this like 5 times and just want to clear something up, i have a 84 mk1 and so i can just jump the postive terminals on the coils right and then all the spark plugs will fire? Or will this not work?

[chris1986]

to Raid 650

as in post #71

The black/white wires are already connected.
If you want both intake and exhaust side plugs to fire, you would need to jumper the blue and blue/white wires together.


i have another question:

what is the ignition signal the black/white wire or the bleu wires?
i need to know that for the bee-r rev limiter

thanks, chris

[s-chassis_only]

what are the benefits from doing this and a diagram would be handy if anyone has one

[Maxpow]

what are the benefits from doing this and a diagram would be handy if anyone has one

The benefits are placebo.

I personally don't care too much for this mod, I don't think its particularly necessary or a good idea, but if you want to do it, do so at your own discretion.  Several people have done it without issues.

He has spoken.