ej20g coil on plug (cop) conversion

[MrWeedster]

Hi there.

So i bought WRX/STI coil on plug coilpacks to convert my old style two bolt pattern coils.

The thing that concernes me is the grinding of the coils to fit in the hole.

So id like to ask if someone did this conversion to an ej20g and got pics of the grinded coil packs with the drilled holes for one or two bolts, or another idea for a setup.

First i thought i place the coils somewhere in the engine bay and route ignition cables from the coilpacks to the spark plugs, but i dont find a decent place to put them to, so i came back to the original idea to place them directly onto the spark plug. But i dont know where to drill and what to grind to not destroy them.

Cabling and soldering of all the wiring and so on should not be a problem.

Please dont post a link to the nasioc thread. I already asked my questions there, but they dont seem to have the problem with the two bolt pattern.

[kimokalihi]

What year coil packs did you get and were they wrx or sti? I think sti coil packs are too long due to the heads or valve covers sticking out further or the hole being deeper. You can still use them but you have to swap the long part that attaches to the plug with a wrx or maybe ej20g one. I've never heard of grinding anything. I thought it was plug and play after wiring them in. I have wrx coils waiting to get installed if I ever find time.

[MrWeedster]

I think i have WRX coil packs. The length is very similar holding them together.

Well just try yourself putting them into the holes - They wont fit because they hit the valve covers with the corners.

[cj91legss]

the STI rubber boot is shorter than the WRX rubber boot. This is because of the difference in the head chambers. STI has a shorter spark plug chamber, the spark plug has longer threads as well. The boots are about 1/4" shorter. Can you snap a pic of your spark plug chamber? and a pic of where you think you need to grind down on your coil pack?

[MrWeedster]

The last days i finished the project with the coils.

So here is what i've done:



Left Hand side:


As you see i built a small bracket to put the coils on, was a really easy thing to do.
Then i bought a set of spark plug cables that fit the models without coils on plug and put them on the coils as you see in the picture.

The other side looks more ghetto-rized:


The upper one is attached to the intake manifold with a newly drilled hole (drilled in the coil pack).
The bolt of the lower one (more exactly: every bolt coming with the coil packs) is a direct replacement for one of the bolts for the water tank. So i got the original bolt out and put the coil with the existing bolt on it.

Same as on the left hand side i routed spark plug cables from the coil packs to the spark plugs.


For bypassing the ignitor i built cables to connect the both connectors together:




It looks ghetto but works perfectly.

As you see on the right hand side picture i tried to grind the coils. But the tool sucked (120Watts bench grinder - PITA) so i gave up on that and took the easy path.


Hope this helps someone.

[kimokalihi]

Interesting. Couple questions. Why did you do the conversion? What was your goal by converting? Does it run better now? Did you have to do anything else or was that everything?

[MrWeedster]

Reason was that i have sometimes misfires at a low rpm range around 1200 - 1500 rpm.
That was unfortunately not solved by making this swap.

Anyway, one reason was that the (ebay) supply of the old coil packs gets somewhat rare to get by, so its a good idea to get the new age coil packs as they are more reliable and stuff.

Well the only thing i didn't mention was the electronic side. That means you have to make some wiring to connect the new coil packs to the existing plugs. I think this was the easiest part but the one which made the most work.

I have to differ here. I had two bad coil packs laying around and i wanted to make the whole conversion undoable to get the old coil packs working without welding, cutting and so on.
So i cut off the two pigtails from the broken coils and crimped connectors on them that fit the three pins in the new coil packs.
Then i made two cables with connectors for the ground and connected them from the coil packs to the battery ground.
You see this on the left hand side pic.

Because i had just two pigtails from broken coils and didnt want to cut the good ones, i bought a box of two pin car connectors that are waterproof and soldered them where the old pigtail connectors on the right hand side were. You see this particular connector on the first pic laying on the return line for the water cooler.

Similar to the left hand side i routed the corresponding cables to the right connectors and grounded the coil packs at the ground point ontop of the strut bearings.

For exact connections refer to the topic on nasioc.

[Legacy777]

I would recommend making sure all your electrical connections are water tight. That igniter jumper harness doesn't look like it would be water tight.