What version of MS for a 99?
 

i made a post in the main managment forum and no one replied but i did some research and i think i like MS over them all. Just have one question. I wanna run around 15psi and have 550cc injectors what version of MS is recommended for my setup? And is there a site that offers a conversion harness from oem to a MS standalone

Thanks!

that's up to you. MS1v3 is the most popular choice here, and everything you want to know is provided in the stickies...pin by pin.

Since you have a '99, avoid the MS1 CPU. You want to run the MS2 CPU so you can use your stock crank and cam sensors. The Rev 3.0 circuit board is fine for this application. So in Hustlerese, that's be an MS2v3. In other words, you want one of these two:

MegaSquirt II Engine Management System w/ PCB3 - UnAssembled Kit DIYAutoTune.com

MegaSquirt II Engine Management System w/ PCB3 - Complete Assembled Unit DIYAutoTune.com

Even the assembled kit will require a few modifications to run properly on a Miata, though it's really easy stuff and is well-documented, if well-hidden.


No place sells a pre-made harness to plug it in. You gotta build your own. You might consider doing a parallel install (putting MS in charge of fuel and spark, leaving the stock ECU to drive the alternator, A/C, idle, etc) as this will require less circuit-building on your part, at the expense of a lot more wiring.

thanks joe that cleared alot up for me i was like a deer in the headlights there for a long time.

No prob.

To reduce the total volume of wiring that you have to build yourself (and simplify the finding of connectors) you could start with a Boomslang ECU Extension cable. The idea is that you use this short extension harness as the point to patch in the MS, cutting and/or splicing only those wires necessary to feed the MS. They're not inexpensive, but would be a very serious time-saver and also permit you do to all of the wiring modification on your presumably comfortable and well-lit workbench, rather than while standing on your head under the dashboard of your NB, with your torso wedged between the seat and steering wheel, crippling yourself permanently. (Can you tell that I hate working on NBs?)

I'm doing a how-to for a '99 here. It's nowhere near finished, but it should give you a good idea of what to expect.

:bowrofl: thanks soo much joe i might be able to pull this project out of the dark now. i bought everything i needed to finish my setup spent $1600 and got a pretty nice kit going

.63 ar t4 turbo
jgs mani
ms2v3
550cc injectors
2.5" ic piping 28x12 ic
greddy bov
tial wg
3"custom dp
sidepipe exhaust with flowmaster muffler

What mods are required to the assembled MS2 kit to run a parallel install on a '99 or '00?

search "ms 99" and you will find all info. many have done it, but many also failed. whether you fail or succeed depends on your electronics skills.....

Thanks - doesn't sound too encouraging.

You have no idea how many times I have gone back and forth about trying it on my car. For every single encouraging success story I have read either incorrectly wired or set up or something wrong from someone. If you can pull it off thats badass, but I'm not going to lie and say its a walk in the park. Though many make it out to seem that way.

1: Input circuits for crank and cam sensor. Build either Abe's circuit or Jason's circuit here: https://www.miataturbo.net/forum/t25789/#post305857

2: Output circuits for spark drive. Build as per the regular MS1/NA DIY instructions here: How to MegaSquirt your Mazda Miata or the "official" version here: MS2-Extra Ignition Hardware Manual Personally, I like the design of the second circuit better (you won't accidentally fry your coils by reflashing firmware with the ignition plugged in.)

Joe, the 5V pullup method is for COP's it seems, or does this work with the stock coils as well? If so, it seems odd that (almost) everybody uses the dangerous DIY method while simply adding 2 transistors would fix that problem?

It will work with any coil that has an accompanying igniter which accepts a +5 trigger, which includes COPs, '94+ coils (with built-in igniter), and 1.6 coils with external igniter.

Actually, now that I look at the transistorized circuit more closely, I think I was wrong about it being "fry-proof". Unless the CPUs output pins are tri-stated at powerup, those PNP transistors are going to conduct. I don't have the datasheet on me just at the moment.

At one time, it seems like there was yet another version of the circuit which was non-inverting, such that the outputs were high when the CPU output pin was high. That would be safe, though for some reason I seem to recall some folks claiming that it didn't work well. I'll have to revisit that at some point.

For now, I guess you should stick with th DIY variant, since we know it works.

So would u recommend me still doing the parallel mod being a noob to standalone tuning.