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Thread: A quick how to use VAG coil on SR20

  1. #1
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    A quick how to use VAG coil on SR20

    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.

  2. #2
    Guest diamondsink's Avatar
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    Real nice write up, always thought about doing thi but never really looked into it. Actually looks like a simple job as long as you good at soldering and loom making.

    So is this the NGK Audi R8 coil http://www.ebay.co.uk/itm/New-NGK-Ig...gAAOSwpDdVTNo1
    Last edited by diamondsink; 04-01-2016 at 20:09.

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    Quote Originally Posted by diamondsink View Post
    Real nice write up, always thought about doing thi but never really looked into it. Actually looks like a simple job as long as you good at soldering and loom making.

    So is this the NGK Audi R8 coil http://www.ebay.co.uk/itm/New-NGK-Ig...gAAOSwpDdVTNo1
    It's an ok job, just takes time and patience to do it right. I have a lot more info hiding in my head, so just ask if you need anything. Access to do the ignitor bypass wasn't great for me due to having a top mount but I struggled through. If it was too much of an issue I could of just removed the compressor but didn't need to.

    Yep, it's the red NGK r8 coils which are meant to be good and upgrade for the vw boys.

    You can get them cheaper as a set.
    http://www.awesomegti.com/red-igniti...ck-set-2-0tfsi

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    Guest speedingmofa's Avatar
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    Thanks for sharing this info dude! I'm very interested in this conversion. Specially since it's going into a VE head and the diameter for the plugs are narrower.

    Where did u get the plugs btw? I have a spare coil loom from an SR i could use.
    Also, can u get me some measurements, like the diameter of the rubber cover and the length up to the cover?

    Found a pic of what i needed:


    Once i get a chance, i'll get measurements of the rubber cover up top.
    Last edited by speedingmofa; 18-10-2016 at 19:13.

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    Guest norfy's Avatar
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    haha, you beat me to it!

    been doing these conversions for a while now and was meant to do a similar write up.

    if i could add some info;
    with the stock ptu i also struggled to find new male connectors, so i opted to either hard wire such as you have done or use an old ptu, gut it and solder cables across creating a plug and play bypass which imo gives you more flexibility in the future and doesnt damage the stock loom.

    you shouldnt need to add an external power feed/relay, the stock nissan power feed is overkill for the vag coils and runs a 30a relayed circuit anyway.

    you can buy new vag coil pack connector kits from vems https://shop.vems.hu/catalog/active-...6ba20b277dea78 and they come in at around £15 delivered. as they come with pins and boots it means no soldering is required on this part.

    also i find you have to angle the coils a little to allow the connectors and looms to pass each other nicely. and this works for all sr20 (straightcam or vvt)



    other than that, good work dude!
    Last edited by norfy; 18-10-2016 at 10:53.

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    Guest norfy's Avatar
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    heres mine


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    Can someone give me a link to decent quality cable? A small roll would be fine.
    I used cabling far too thick on my 1st loom so cut the connectors off and added them to my stock loom as a 'temporary' solution, 1 year on I'v had no problems with up to 24psi on stock plug gap, 1.1 iirc

    I'v been meaning to make 2nd attempt at a loom but never got round to it. I'l do a step by step guide once done and add to this thread.



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    Norfy, its actually came full circle because it was a picture of that engine you built years ago on an engine stand that I seen you were running the black top 1.8 coils which got me thinking about it all!!!

    Ive been needing to provide an update for a while. So ive ran these all summer and no issue at all. Ive had a play and even when gapping plugs out to 1mm there is no sign of blow out at 1,7bar so a worth while upgrade however on daily basis i run .75mm.

    Mofa length up to the cover is 131mm, that's just info from google. im not at the workshop this week to check diameters.

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    @s200rat Thats perfect bro, i'm in no hurry! I'll compare the dimensions with the regularo spark plug covers that normally come in the VE motors.

    Guys, again, you're doing a great job sharing this stuff with the public. I'm so glad i came across this thread, i was going LSx coils mated to the regular spark plug wires goin in the ve head, but this seems like a much better deal as it's practically a direct fit and keeps the engine bay relatively clean and stockish!

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    Guest norfy's Avatar
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    Quote Originally Posted by s200rat View Post
    Norfy, its actually came full circle because it was a picture of that engine you built years ago on an engine stand that I seen you were running the black top 1.8 coils which got me thinking about it all!!!
    how weird haha.

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    Guest speedingmofa's Avatar
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    I got the dimensions of the sr20ve plugs. Does anyone have the dimensions of the audi coils for comparison? I'd also like to know at what power levels these coils have proven themselves.

    Btw, these are the effective dimensions. What i mean by that is, what I measured are the insides of the rubbers, the part that matters and seals.
    At 131mm length, it's slightly longer. I wonder if i could still get it to seal by putting on a rubber grommet of the right diameter. By the looks of it the seal on the audi coils seem way too narrow.



    Edit:
    Found these dimensions through google. Can anyone confirm?

    Overall length: 143mm
    Top of the black seal: 31.5-32mm
    Toward the bottom goes down to (not counting the parts that stick out to seal the hole): 27mm
    Smooth metal below it is: 22mm
    The gun suppressor looking part below it is: 20mm
    The bottom part you marked where the spark plug goes and the part above with the black circular nubs is: 18mm

    Last edited by speedingmofa; 10-01-2017 at 20:22.

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    Guest speedingmofa's Avatar
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    All right knuckle heads since you won't provide me with the details, and i decided not to wait any longer, i bought a set myself to do some measurements

    The results:


    And here test fitted on the sr16ve cam cover:


    Those with a good eye would have noticed the inner part that seats onto the spark plug is 5mm taller. Not sure if this is going to be a huge problem, i might get away with a bit of grinding of the valve cover to get them to seat slightly further in. I'll know as soon as the motor is finished for sure :P
    Last edited by speedingmofa; 10-01-2017 at 22:53.

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    Guest Drifter's Avatar
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    Has anyone had any miss fire issues after installing these coils? Only reason I ask is that I've just replaced a set of Splitifires on my mates R34 GT-T, and now it's being a twat when it gets hot, spluttering and eventually stopping, the only other symptom is I can here the coils click every so often. I've checked all the wiring, changed earth positions with no luck. I thought there was an earth problem as with the main earth disconnected from the chassis I could still get continuity, but it turns out the metal casing that clips to the sparkplug is also connected to pin 4 on the plug. At least I guess it's supposed to? The R34 is like an S15 so igniter chip interfering.

    Any ideas would be really helpful

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    Quote Originally Posted by Drifter View Post

    Any ideas would be really helpful
    What ECU do you have?
    I don't have access to my laptop to check the base map for the r34 but I remember the dwell time is higher than the Sr for the ignition.

    Think it's over 2.0ms whereas for a coil the size of the vag all you need is 1.5 to 1.8ms. Your potentially overheating them with the long charge time.

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    Thanks for that, having tested again this morning with the original loom and Splitfires there's a big difference in the max current at the coil. I'm lucky enough to have access to a PicoScope system so I can see what the coil is up to. Dwell is currently around 3ms, with the standard loom and coil it reaches 6.6A, with the VAG coil and my loom it reaches 16.6A. Back to standard it runs fine, no problem. ECU is a Specialists Components Delta 800 standalone. I think you're right that the dwell is too long.

    This is the graph from the VAG coil, blue is coil current, red is ecu signal voltage, green is coil voltage and brown is coil earth.
    vag coil by Scott Berry, on Flickr

    Didn't save the Splitfire graph, only got a photo but the graph scale is the same. You can see the coil current is much lower.
    IMG_2955 by Scott Berry, on Flickr

    My loom, red wire 12V from new relay, white wire 12v ign switching new relay, short black signal earth and long black coil earth.
    IMG_2953 by Scott Berry, on Flickr

    All the joints are soldered together, they're all taped, just unwrapped this one.
    IMG_2954 by Scott Berry, on Flickr
    Last edited by Drifter; 26-02-2017 at 15:34.

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    Would this conversion work on a series 2 rb25det? Because the standard coils fail all the time

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    Quote Originally Posted by mike85sx View Post
    Would this conversion work on a series 2 rb25det? Because the standard coils fail all the time
    Yeah I think so, but iirc you'll need to bypass the ignitor chip.


    Sent from my iPhone using Tapatalk

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    Awesome you have access to a scope! Your graphs are supporting the cause being excessive charge / dwell so I would say it's worth knocking the time down to 1.8 as a starting point.

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    Quote Originally Posted by s200rat View Post
    Awesome you have access to a scope! Your graphs are supporting the cause being excessive charge / dwell so I would say it's worth knocking the time down to 1.8 as a starting point.
    Yeah, all the gear, no idea My boss bought it to try and tune his Capri turbo, but gave up on it in the end, cost over £2k

    The software for the ECU is free access so I've got that, but need a USB-CAN interface to connect to the ECU. I might try and borrow one from the guy who's mapping it, I'd like to check it's all working before dropping it off. Failing that my mate can buy the lead as it will come in handy for future if somethings up. We're used to the PowerFC and the hand commander so it's always been easy to diagnose stuff.

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