Below is a guide / my notes on how to convert over to run VAG 115 coil packs.
The background behind this is that like most that run high boost I’ve found the limits of the 15-20 year old coils we have on the 14/14a’s. With standard coils, I found that anything above 1.55bar the spark would blow out and even gapping down to the likes of .55mm would still not produce reliable ignition. Ive mapped and run the car at 1.7bar on a 3076 so obviously want something that would provide consistent spark.
I’ve thought about all the standard options i.e. hot wiring the OEM’s, splitfire, yellow jackets, LS1 conversion but finally settled on the VAG coils. I’ve seen a lot of other cars running them, some with silly HP. Im a believer that technology has improved in the 20years since Nissan produced the coil so the pattern “performance” coils don’t bring much benefit. The VW coils are ideal because dwell is same as the Nissan coils. Another benefit is that they are fairly cheap (Approx. ½ the price of aftermarket replacement coils). Have a search for TnF on here and read the CA18 coil conversion post for all the technical pro’s.
They are longer so you’ll have to ditch the cover but ive never ran a coil pack cover so no loss there. Also they don’t screw down, they are retained by theyre own internal gripper.
Anyways onto the conversion.
You’ll need;
4x 1J0973724 coil connectors with the terminals.
4x 115 coils
Plenty of thin wall automotive wire, loom tape, heat shrink, solder iron, snips, cable stripper, crimper.
The conversion is in two parts. 1. Creating a new sub loom for the coil pack and 2. Bypass the ignitor.
1 – New sub loom.
Plenty ways of doing this. The easy way would be to retain the Nissan wiring and chop the connectors and graft on the VW. However, I think the weak spark is partially due to the wiring as well – the very same as what happens with the fuel pump. So I created a new sub loom.
Cut the main connector off, this is the only part you need. It contains 4x ignition triggers, 1x 12v and 1x ecu feed for #1.
The Nissan coils have 3x feeds, 12v, trigger and ground. The 12v and ground have room for improvement!
The VW coil has 4 feeds due to the inbuilt ignitor. On the coil they are numbered. #1 12v, #2 signal ground, #3 signal, #4 power ground.
What I done was use the original 12v feed to trigger a relay to deliver direct power to my loom from the main relay box.
The triggers ran to each coil plug as required.
And 2x independent earths to each plug.
I kept the earths independent to avoid creating ground loops and grounded the signal wire to inlet manifold and the power to the body.
This is the finished sub loom
1 – Ignitor bypass.
Because the VW coil has its own ignitor there is no need for this. I tried to find male plugs in order to make a patch loom but couldn’t find them so unfortunately had to chop the plugs off the loom and solder the tail ends together. I notice on the various forums there is a lot of conflicting info regarding the wiring here. There shouldn’t be – its simple. No need to go into detail about transistor amplifiers, all you need to know is E1 should be wired to I1, and E2 to I2….. The ground is surplus to requirements. Just tape this up to avoid issues as it’s a common ground to several other ECU pins and the IACV. I did consider opening up my ignitor and bridging it but decided against ruining a perfectly good unit.
Wrap everything up in heat shrink and loom tape and you should be good to go.
I re-gapped to 0.7mm and went for a test drive and all good so far, however it’s a wet day so basically just spun its wheels so not a true test under full load but appears good so far that its supporting the larger plug gap.