The Top Mitsubishi Galant VR-4 Resource

Join the best E39A 1991-1992 Mitsubishi Galant VR-4 community and document your GVR4 journey.

  • Software Upgraded - Reset Your Password to Login
    In order to log in after the forum software change, you need to reset your password. If you don't have access to the email address you used to register your GVR4.org account, you won't be able to reset your password. In that case, follow the instructions here to regain access to the forum.

Coil on plug build

kron_jdd

Active member
Joined
Mar 27, 2011
Messages
33
Location
calgary, alberta
Hey all, this has most likely been asked by many but I couldn't find the link. I want to make my own coil on plug set up but had a couple questions. Why is it that from what I have found, that the coils are wired in series vs parallel circuit and does it truly matter what 2 pin coils I use? I have 4 Ford coils and was hoping to use them as they are a 3 spark coil. Any info is welcome
 

bradrs

Well-known member
Joined
Feb 1, 2014
Messages
128
Location
Alta Loma, CA
They are wired series instead of parallel, because that is the way it should be done.

One coil is firing the cylinder under compression, the other coil is firing into the exhaust stroke(waste spark). If you parallel them, then the coil that is firing the waste spark fires first, and will reduce the energy going to the coil that you want to fire. When they are in series, both coil primaries see the same current.

It only matters which coil you use, if you want it to work. If you keep the stock ignition, you need to match the inductance/resistance of the sum of the 2 coils(since they are in series) to approximately the values of the stock coil. This will ensure that your dwell settings in the ECU will properly charge the coil at higher RPM, and not cook the coil at idle.

IF you convert to CDI when you do a COP, it reduces the coil matching issues, because a CDI doesn't need dwell. A low resistance coil is better, to keep the CDI from overheating the coil. If you don't convert to CDI, then your COP will likely not perform as well as a good condition set of stock coils.

Not familiar with which Ford coils you are referring to, but on some systems it trigger the coil to multispark from the OEM ECU. The coil itself may not multispark without the ECU telling it to.

 
Last edited:

kron_jdd

Active member
Joined
Mar 27, 2011
Messages
33
Location
calgary, alberta
Ok so why things are wired the way there are makes sense. Checking inductance and resistance makes sense but what are you talking about in reguards to the CDI? Is that another apart that I have to wire in? So I can not just wire the new coils in the a connection where the old coil pack plugged in.
Thank you again for the info
 

thomcasey

Well-known member
Joined
Sep 24, 2014
Messages
907
Location
Indianapolis, IN
Here is an EVO example of a CDI . Basically it is a spark box that provides better spark than the coil. COP will work without one, but you will find Sparktech and those companies recommending them for reliability and better performance.
 

bradrs

Well-known member
Joined
Feb 1, 2014
Messages
128
Location
Alta Loma, CA
The coil on plug coils will not match the stock coils. The stock ECU charges the coils for a set period of time, called dwell. This time will vary with battery voltage and RPM. But the time the ECU charges for needs to match the time the coils need to charge for, to get good energy storage/strong sparks.

If you get coils that are mismatched to the stock dwell, then you could have a really good coil, but still have it make a really crappy spark because it isn't matched to the stock system. That is why I have always said that COP isn't really a good idea without adding a CDI.

You may find that just the COP(no CDI) works a little better or worse than stock, depending on the condition of you stock parts. I've seen people report some improvements, and also seen some people have it work worse than stock

CDI changes the ignition. Instead of dwell storing energy in the coil, the CDI ignition box stores energy in a capacitor, then dumps it into the coil. So dwell becomes irrelevant. And CDI will make a COP provide a much stronger spark than stock, regardless of the stock dwell.
 

kron_jdd

Active member
Joined
Mar 27, 2011
Messages
33
Location
calgary, alberta
So if I did not have a CDI but the inductance/resistance was the same between factory coil and CoP, with a new factory coil pack I would see like to no improvement? My problem is that I have a na block that I have changed everything I could to support a turbo but if I push more the 10psi I have misfire at WOT I have the copper NGK plugs at .26" so what could I be missing? I don't have the correct knock sensor. Is that my problem? Could the ECU be pulling timing?
 

thomcasey

Well-known member
Joined
Sep 24, 2014
Messages
907
Location
Indianapolis, IN
Are you still running the NA pistons? They are higher compression. For about a year and a half, I ran an NA motor in my TSi. In order to help with detonation and knock, I just filled up with 1/4 tank of e-85 then the rest with 93 octane. It let me run 15lbs. Engine ran strong the day I sold it.
 

kron_jdd

Active member
Joined
Mar 27, 2011
Messages
33
Location
calgary, alberta
Yes the engine still does have the NA pistons which I my info is right, that Gives me a 9:1 vs the 8:1 of the turbo blocks. It feels like a misfire tho not knock, I do run mid grade to premium fuel.be 89-93 octane respectively. Should I only run premium? I did do some reading where that if the knock sensor isn't working or not correct, the ECU will pull timing at WOT. Just not sure what road to go down. Sensor, spark plug gab, or a CoP upgrade
 
Last edited:

Eztoril

Well-known member
Joined
Aug 31, 2016
Messages
80
Location
Irvine CA
Hey bro not sure if you have seen Jafro's video on building a COP yet ? here is a link. Jafro's videos are awesome. Wish I had met him while I lived in Virginia.


Btw - I was thinking about doing this as well, cause it makes everything look more modern and sexy under the hood but after seeing that, if it's made incorrectly in any way you will have problems. I would assume before doing this mod, you would want everything running and functioning perfectly under the hood while using the stock spark plug wire setup and then proceed with installin a COP setup. Oh and the correct knock sensor would be where I would start.


coil on plug by Jafro


 
Last edited:
Support Vendors who Support the GVR-4 Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications RixRacing RockAuto RTM Racing STM Tuned

Recent Forum Posts

Top