Sumitomo DL090-3 Male is what you need

http://www.cycleterminal.com/dl-090-series.html

 

WoW this is great! I have been searching for the past 3 or 4 days for any pn for this connector. Turns out that connectors are the hardest part to find. I did however know that they are OEM on Mazda RX8s, some Suzukis, and Nissans with SR20s, but finding the actual pn is a whole other story. Other than SpoolinUp, JD Customs & MAP, I wasnt even able to find a single Electrical Connector website that wasnt Alibaba or Aliexpress... So thank you!
Now if i can only find out which Suzuki, Nissan or Mazda models come with them stock! At this point its not even about the money, it never was, i just like having the information!

 

Definitely a great writeup, I look forward to doing this myself

 

Electrical potential is between two points. If the potential is galvenically isolated then the two grounds and voltage sources are separate. The voltage on one side has a different ground path and thus does not effect the other side (unless you screw up and cause bad ground loops). The voltage generated by a switching or alternating current at the primary side induces a voltage on the secondary side which value will depend upon the turns ratio. As, I am sure everyone knows an alternator and Tesla coil make greater voltage voltage from a low voltage source this way. The induced voltage on the secondary side will not jump across the barrier unless you exceed the voltage rating for the rated conditions, baring mfg error

If you were to cross the isolation barrier with a direct connection bad things would happen. Grounds are keep separate except for a point using a capacitor or resistor to allow for transient currents.

A pulsed power application like the spark plug, current will travel from its positive potential through the plug then into ground. Which immediately loops back around. It does not necessarily have to travel home first. Current may flow into and out of the ground plane and to the battery. The ground loops will determine available paths.

Sorry to necro post but this triggered me.

 

yesterday I test fitted my coils and they sit very low WITHOUT the mounting plate. I see that with the mounting plate my coils would sit kind of high off of the plug. is everyone else's like that? is that normal?

evo 9, 06 scion xa oem coils

 

I think thats normal with the toyota coils. If you dig into some of the how-to's I think its pretty common to stretch the metal coil that contacts the plug so that it makes a good connection.

While we are here though I can update the previous discussion on ground paths, knowing perhaps a little more now. Both sides of the transformer (ignition coil) Primary and Secondary are tied to chassis ground. So the return path is simply, head -> chassis -> secondary. I've been planning on adding a ground straight from the head to the coil harness to shorten that at some point.

 

thanks for the feed back. I will be waiting to see your right up on the ground wiring.

 

Dont know why my diy cop doesn’t work..it idles 5 sec then die..cant start it back..put back original coil car goes fine nothing happened..

im using k20 3 pins coil from honda and carefully checked all the wiring for any miss connection..all fine and good..