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1JZ Cheap Coilpack Upgrade

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1NZ Coilpack Upgrade for 1JZ

Matthew Salkeld


This guide is intended to demonstrate how I replaced my standard 1JZ coilpacks with 1NZ coilpacks in order to allow for cheap future replacement as well as upgrading ignition energy and removing bulky electronics.


Update: Got a prototype igniter replacer ready, just need a volunteer to test it and it'll be all good!


Basically, standard 1JZ-GTE and 2JZ-GTE coilpacks suck. They really do. They deliver great spark, as many big power cars have demonstrated, but they're just too fragile. Cracks and fissures develop over time all over the coilpack body and this dramatically reduces their spark energy (much of it ends up shorting to the head). Often these cracks are not visible to the eye but that doesn't mean they won't conduct perfectly well (into the head, not the spark plug). I went in search of aftermarket options but quickly discovered the only easy drop-in solutions were extremely expensive or reputedly suffered from the same problems as the original coilpacks (I'm seeing red). Eventually, my search took me to the later model Toyota coilpacks.




Thanks to Anthony of ae86drivingclub for compiling some info


Basically, these coilpacks are all the same. The only apparent difference is the angle of the connector with respect to the mounting hole and the length of the coil itself. My best guess is that all of these coilpacks deliver the same ignition energy (reputation is for well over 100hp/cylinder) and only differ in size. They even have similar part numbers (90919-022XX). They can be found at virtually any wrecker in any country for a very reasonable price. Plugs can be purchased new from toyota or cut from looms at the wreckers. If you want new pigtails, that can be done too.


What you'll need:


6 x 1NZ coilpack ('05 Yaris/Echo 1.5L engine - there are MANY other coilpacks that will also work; differences are height and connector angle only).

- optionally: a bracket to hold them all in place.

- tools to make a loom and shave a few mm of plastic off cyl 4/5 coilpacks.




My design goals for these brackets were as follows:

- Cheap to make

- Coilpacks must be accessible (unpluggable and removable) without removing entire bracket

- Constrain movement fully


Amusingly, I was in such a rush to put it all together I forgot to take any photos of it. It's a CNC machine piece and here's a render of it. To make the plugs accessible I needed to have them angled away from each other very slightly. Also keep the standard Toyota coilpack bolts because they're a direct fit for my bracket.



Although it's a 3d model (3mm thick aluminium) there wasn't much point showing it off at an angle because that just makes it look all wonky. Anyway, I'll be selling these, if anyone wants to save themselves the hassle of having them made up. They'll be quite cheap. After you've got your coilpacks and a plate to hold them in place you'll need to make a loom.




Took me half an afternoon to make this. Coilpacks need an 8A ground, 8A fused, ignition switched 12V power source and a 5v square wave ground trigger. the 5v square wave is pretty standard and I guess most ECU's will output this natively (I used a Megasquirt 3 w/ MS3X for full sequential). Bear in mind that each set of odd/even cylinders will draw power in alternation AND at a low duty cycle (around 20% @ 9000 rpm) so you can use a lesser gauge wire if you want to. I went way overboard and used up all my scraps of 10A wire so my loom is chunky as, in future I'd use 5A or 7A wire).




Final fitment after a very spirited drive. All my misfire at high boost is GONE. The car drives far better than it ever has before. Drives more smoothly, idles better and my air-fuel ratios are much steadier. Acceleration is much more crisp and boost feels much better. Bad coilpacks are really hard to diagnose because the car still runs reasonably well. Now it runs better.


Also, the standard coilpack cover can be fitted over top as long as your loom isn't too chunky (I can't get the cyl 6 bolts in with my loom but it still looks great with the cover on or off), if you're wanting a stealthier look. Also, after a VERY spirited drive I've tested the temperature of the coilpacks and they're within 3 degrees of ambient! Go touch some standard 1JZ coilpacks after a tough drive and tell me if they feel ambient to you. I suspect that my bracket is shielding the heat away from the coilpacks.


PM me if you need a bracket or loom made ($POA).





Update: And here's my igniter replacer prototype in all it's wondrous beauty.


Edited by mUnky-matt
  • Upvote 1

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Awesome write up. I got all excited until I read "stand alone" ecu required :( Will definitely consider this if I ever get to the stage where I need a standalone.

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Yeah I made it rainbow for that reason. I suspect that I could make them work with standard ECU but I'd have to build a box to translate the standard ECU fire command into a 5v square ground trigger.. in fact, maybe it already is. I'll look into it.

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Well you might be in luck, I believe it can be done. There is no cost difference between 1JZ and 2JZ, they both use identical ignition regimes. I need to find someone locally with a 2JZ so that I can determine that 1) my bracket fits and 2) the standard ECU can drive the coils.

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Standard ECU can definitely drive the coils, just need a little bit of trickery to simulate the return signal correctly. Gotta find a way to package it in the standard ignitor.


Did some more testing today... put thermocouples all over the head. During a very vigorous, long drive I found that coilpacks peaked at ~46degrees, cam covers at 72 degrees and spark plug valley tracking similarly to but higher than cam covers (before it came loose). Makes me happy!


I'd say that since heat cycling is the most likely culprit in the hunt for the mysterious coilpack killer, this can only be a good thing :P

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seems like the alloy plate is a big heat sink that draws temps off the coil packs, sounds like it should be applied to most other engines :thumbsup:


edit: yeah i missed the part where its only 3mm thick <_>

Edited by SILVIA s13

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Perhaps.. I look at it more like a heatshield tho... I left the rubber boots on the coilpacks to there's a fair bit of rubber between the plate and the top of the COPs...


Also, need a test car to see if the stock ECU will run them; have figured it all out.

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Hi everyone!

I just joined up because I found this thread.

I've just converted my factory 1JZ JZA70 supra to use these coil packs. I can confirm that it runs fine on a standard supra ECU.

With the IGf signal wires from each coil it is possible to solder them together and run them back to the ECU IGf directly. No problems there.

However, the only issue I have is that by deleting the standard ignitor I've no longer got an RPM signal that feeds back to the stock tacho. I've tried tapping the grouped IGf signal but that isn't sufficient to drive the tacho.

Any ideas?


PS. There seems to be some script running on these web pages that makes inputing text very difficult.

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So from what i've read here, the 1NZ coils will work with a 1JZ JZA70 stock ecu? All thats needed is the loom and the bracket? What about the stock ignitor...not needed anymore? Is there anything that takes its place? And can the tachometer work without the stock ingnitor?


I'm quite interested in your loom and bracket, kindly pm the price.


Hope you can shed some light on these questions I have as I dont really have a deep understanding as to how the ignition system works.


Thank You.

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