MS-II on a 94 N/A - Miata Turbo Forum - Boost cars, acquire cats.

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Old 12-25-2007, 04:23 PM   #1
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Default MS-II on a 94 N/A

First post, let me introduce myself in a sentence or less: bored ex-computer-security-geek, SCCA autocross-junkie, brewing beer commercially while rethinking my life ("seven years of college, down the drain...").

I no longer work full-time and am looking for a project to fill some free time in my life. In a former life, I built a ham radio from a kit and I enjoy electronic tinkering, though I'm fairly rusty on the stuff I learned in that "Physics of Electronics and Computers" class taught by that professor with the bad B.O. Anyhow, I can wield a soldering iron pretty well and am ---- enough to line up the bands on a resistor "correctly". Even though I'm staying NA for the foreseeable future, I'm thinking it'd be a good exercise to do this MEGAsquirt thing, and this is apparently the best Miata forum for the MSes (I run a 94 C-package).

So. I've read up as much as I can, so go easy on me.

I'm thinking of doing a MS-II, simply because I'm afraid a MS-I would be too easy. The docs seem to indicate that the 90-97 Miata falls into the 4/2 wheel category (still learning about that one) along with the Mitsu engine - am I right that this these are the two circuits I want to build? Will this theoretically work "out of the box"? I assume I would build this as driving my stock ignitors, omitting the VB921s.

Is the extra MAP sensor for baro correction worth doing now? Do knock sensing now? Anything else I should add for for a great baseline build? I'll add things into the car slowly, but it seems smart to build the entire thing now and just hook up more stuff after I get the basics working.

I've been assuming that I'll need a WBO2 system to do road-tuning and auto-tuning. I don't have the cash for dyno tuning (unless I can trade it for beer, seriously), will I be able to get a decent tune without it? I'm looking for some gain in power (through eventual MAF delete), perhaps a bit of increased cruise economy.

Anyone use JAW WBO2? It doesn't seem supported by default in MegaTune. Is it dangerous to do both DIY WB and DIY ECU?

Can I continue to use 87 (remember, I'm NA and out of work), or will I be making changes that can actually take advantage of 91+? Can I do maps for both?

Any CSP autocrossers in here and willing to share experience?

Thanks for all your help (your threads have been great!), please go easy on me!
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Old 12-25-2007, 05:52 PM   #2
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You can continue to use 87 but it will limit the power you can make because you won't be able to run much advanced timing. You can make two tables though, one for 87 and one for 92/93 with advanced timing. Arkmage is using the JAW, not sure if he ever got it working right with MS though. You will need a wideband. You can get a good safe tune without a dyno but tuning timing will be difficult, time consuming, and sub-optimum without time spent on a load bearing dyno. You're right about the cam sensor outputs. MSII will be easy using the CAS.
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Old 12-25-2007, 06:02 PM   #3
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Cool, thanks for the info. I always figured I'd have to back off the advance if I continued to use 87, but I wasn't sure how that would impact actual power.

My understanding was that twiddling the CAS to advance timing on an NA engine only moved the power around, it didn't actually make more of it. I assume that the MS will make more power with advanced timing because it's a new timing map, not just a shifted stock map?

I'll see if I can chat with Arkmage about the JAW, going DIY on the WBO2 would make this exercise more fun and palatable to the wallet.
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Old 12-25-2007, 06:09 PM   #4
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You can get the AEM Uegos cheap on ebay. Like $225 shipped, that includes the gauge and all. For that price, it's worth not having to mess with the Jaw unless arkmage figured it out.
With the MS you'll be able to advance the entire table where you need it to make optimum power 100% of the time. There really isn't any compromise.

Fill out your signature and location when you get a chance. Curious where you brew beer at.
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Old 12-25-2007, 08:56 PM   #5
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I don't mind building the JAW, it'd be a fun exercise for me, but if it takes a lot of fiddling or the crazy calibrations described for the PWC controller, I'll pass. I've got a message in to arkmage, hopefully I'll hear from him soon. I never saw any resolution in his previous thread, hopefully that was a tuning or leak issue and not a flaw in the JAW.

Are the AEM 30-4100s generally considered as good as the LC-1s? I don't typically think of AEM as a quality company, but that could be my Solo bias...

I've updated my location and signature, but I'm pretty sure you've never heard of us. We're a tiny brewery, distributed mostly in CT, parts of NY, and perhaps Florida? I'm learning the ropes, everything from the actual brewing down to scrubbing fermentation tanks. It's not glamorous, but it's fun and rewarding.
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Old 12-25-2007, 09:43 PM   #6
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I have the AEM 4100, Paul has 3 and there are many many other people using the AEM.
The AEM requires you to use the $65 replacement sensor if your sensor fails. I haven't heard of any people having to replace their AEM sensor.
I'm very happy with my AEM. It's easier to install and more trouble free then the LC1, it also doesn't need open air calibration. I see them more as equals, though the AEM is just easier. The only discrepancy i have with the AEM is you have to modify a value in one of the .ini files to make it read Exactly the same in megatune as it does at the controller. You have a choice though, you can modify one file, which takes about 10 minutes of your time with the laptop in the car and never touch it again. Or you can deal with the LC1. I used to recommend the LC1 over the AEM, but after reading everyones troubles with the LC1 and grounding and other things like that. Your choice...
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Old 01-02-2008, 08:11 PM   #7
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Ok, so I've built my stim and it tested out OK. Tomorrow begins the MS2 build.

Would it be useful to anyone if I documented the build for your typical stock 94-97 Miata? The Miata-specific circuits for the MS2 are different than the ones in Braineack's sticky thread. I can try and take pics as I go along, but if no one will use them, I won't bother.

I've got the JAW on order, the harness stuff should be on its way soon, now I just need some wire for the harness, oodles of heatshrink, the VW O2 sensor, and a thousand other little details. Woohoo!
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Old 01-02-2008, 08:22 PM   #8
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getting the ms2 inputs to work is cake, I got that working over half a year ago. Getting the spark to work is something I was not successful in doing. The ms2 cpu puts out less amps on its spark outputs than the ms1 cpu.
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Old 01-02-2008, 09:14 PM   #9
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yeah, it seems straightforward except for one issue, which wire from the CAS goes to which input on the MS2? I haven't looked that far into it, probably easy to deduce.

were you using the stock ignitors, or something else? I hadn't anticipated problems with the output...

still, there's no comprehensive, step-by-step guide to help noobs like myself. If it were going to be useful, I'd be happy to do it...
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Old 01-03-2008, 09:32 AM   #10
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Quote:
Originally Posted by neogenesis2004 View Post
getting the ms2 inputs to work is cake, I got that working over half a year ago. Getting the spark to work is something I was not successful in doing. The ms2 cpu puts out less amps on its spark outputs than the ms1 cpu.
The amps would have been an issue with the old Kags mods. However, the MS2/Extra setup uses a set of transistors to amplify the output, so this is less of an issue. Check out this link for the MS2/Extra setup:

http://www.msextra.com/ms2extra/MS2-Extra_4g63.htm

This is still beta code and may not have all the bugs shaken out yet.
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Old 01-03-2008, 09:42 AM   #11
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+1 on the AEM UEGO (or should I say 3?)
As Chad said you do have to modify a file to make the gauge display in megatune match the AEM gauge and you also have to make a change to make the AFR tables use AFR instead of voltage but they are both easy enough. After that you are golden. The AEM is very accurate, my dyno pulls this Monday proved that.

that LC1 gauge is sexy though.
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Old 02-01-2008, 10:17 PM   #12
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OK, the MS2 is up and running, and I finally have my harness together.

But I'm not seeing any RPM while cranking, hence she won't spark/start/anything.

I built the input/output circuits exactly as instructed in the MS2Extra docs. I tested with a JimStim, and everything worked fine, including RPM. So I figure it's my harness.

The 4 slot sensor comes in from the CAS on the White wire (2E on 94-95 harness) and is connected to pin 24 on the DB37. The 2 slot sensor comes in on the Yellow/Blue wire (2G on 94-95) and is connected to pin 3 on the DB37.

Both these signals are currently shared with the OE ECU.

What am I doing wrong? I'll go back over my harness again in the morning, just in case I botched something.

Ignition Options are:
Spark Mode - 4G63
Trigger Angle/Offset - 10.00
Skip Pulses - 3
Ignition Input Capture - Falling Edge
Spark Output - Going Low
Number of coils - wasted spark
Spark A output - D14
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Old 02-05-2008, 03:48 PM   #13
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looks like i need to amplify the input. spinning the CAS by hand with the car ON, i'm seeing maybe 0.025V on the input wires.

factory service manual is on its way, we'll see if that's within spec. if it is, i'd be surprised that the vanilla circuits the the MS2E docs worked for anyone.

just in case anyone cares, and for future searches.
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Old 02-10-2008, 07:10 PM   #14
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i found the issue. everything in the docs are great, i just had a short between the shield and conductor when i used the shielded gray cable for the 4-slot sensor. it was particularly difficult to track down because the shield was only grounded when the MS was connected. replaced shielded cable with a regular wire, all is good.

having the factory service manual around was key. i also found the IAT and CLT resistance curves in the manual.

it's cranking and seeing RPM now, but not quite running yet.

so, for future reference, the circuits in the 4G63 MS2E documents are exactly correct for 94 miata usage.
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Old 02-10-2008, 07:59 PM   #15
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That's great news. Good job.
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Old 02-28-2008, 09:54 PM   #16
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She Squirts!

It's polar-bear-tit cold here, so I warmed up the car on the OE ECU and then swapped over to the MS. The temperature sensors are all off (again - shared with the OE ECU, using Scott's values in FAQ) so it didn't catch right away, but eventually, she caught!

The car -sounds- different. And it won't idle worth **** (OE is controlling idle, i think i'll get rid of that and suffer the consequences when i go to use A/C). But it revs right up to the 2800 rpm spark-retard redline. Sweet!

There's a lot ahead on this project. Need to get the WB connected and such. Alas I'm starting a new, real job and won't have time for a while. Drat.

Thanks to all who helped!
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Old 02-28-2008, 10:00 PM   #17
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