Planning my VVT swap
 

Hey guys, I’m getting ready to start a VVT swap on my ’91, and I have a complete ’01 donor car at my disposal. I’ve read the megathread and am going to follow the standard formula, nothing crazy. Just hoping to get some confirmation on my plans for building and installing the unassembled MS3 v3.0 kit.

As far as assembly, do I just follow the instructions in section 13 of the MS3base hardware guide, and then make the Miata-specific mods from DIY?

And then for the harness, I need the MS wire bundle from DIY and a male ECU side connector to plug into the factory harness (174917-7 from onlinecomponents.com), along with a db37 that comes with the kit, correct?

With that in mind, this is my complete shopping list for the ECU portion of the project:

MegaSquirt-III w/PCB V3.0 - UnAssembled Kit with black case
MegaSquirt Wiring Bundle - 23" Long
GM Open Element IAT Sensor with Pigtail
3/8" NPT Stainless Steel Weld-On Bung for IAT or CLT Sensor
JimStim v1.5 MegaSquirt Stimulator w/ Wheel Simulator -Unassembl
Wideband – probably MTX-L

Anything I’m missing? Any modkits or similar that are recommended for this setup? I'm open to suggestions - haven't really committed to anything since I haven't gotten the motor running in the donor car yet!

You're missing the ms3x.

Do I really need the MS3X to run the car properly? I'm not planning on forced induction for this build and none of the extra features seem necessary to run a nearly stock motor.

Depends on how much you hate yourself. Normally if you have to ask that question you are better off getting it.

Look at it this way, with the ms3x you solder 1 wire inside. 1 wire only. And it can do so much more. And you can run sequential spark and fuel
Flex fuel down the road. List goes on.

Or you can hate your life.

Hm, ok. Looked into it a bit more and I think I agree with you now. Adding me some X to the list.

I'll be following this thread as I am trying to do exactly the same thing.

You can run all those things and still hate your life. :giggle:

Ok, so after some more research I'm fully in agreement with adding the MS3X, so I'll be going that route. Hopefully will be placing that order today or tomorrow. Current shopping list:

MegaSquirt-III w/PCB V3.0 - UnAssembled Kit with black case
MegaSquirt-III MS3X Expansion Card
DB37 solder cup connector for MS3X
MegaSquirt 3X Wiring Bundle - 23" long
MegaSquirt Wiring Bundle - 23" Long
GM Open Element IAT Sensor with Pigtail
3/8" NPT Stainless Steel Weld-On Bung for IAT or CLT Sensor
MegaSquirt Stimulator / DIYPNP Power Supply
MegaSquirt Stimulator v2.2 - UnAssembled Kit
Anti-Static ESD Protection Wrist Strap

For assembly, does the V3.0 board assembly guide for MS2 still apply to the V3.0 board with MS3? Seems like it to me, and this guide is more in depth than the one in the MS3 hardware guide... :noob:

In other news, I got the donor car running yesterday, and it purrs, even on two year old gas! Will commence removal of that engine today.

If you want the stimulator you also need the jimstimx. I would just skip the stimulator.

Also why stainless bung. Do you plan to have stainless intake pipiing?

I was thinking I could test just the mainboard for functionality with the standard stim like DIY recommends, whereas the 3X board should be functional out of the box, not having been assembled by an amateur solderer. If I can safely skip the testing portion, I'd be fine with that too.

Intake plans aren't 100% yet, but it's likely to end up with the sensor JB-Welded to either the stock intake or hopefully one of the sweet 3D printed ones.

Ok guys, pardon my ignorance, but once again I've done some more reading and pretty much answered my own questions (search, noob, right?). I've realized that by using the MS3X, most of the work will be done by that card, and as a result I'll be building much fewer circuits on the mainboard. Thus, the standard stim won't be able to do much and to get the ability to bench test operation of the ECU, I'll also need the stimX card to test those 3X circuits. Since I was really only interested in getting it so that I could check if I'd screwed up the assembly, I think I will skip the stim and do the manual tests with battery and voltmeter.

With that now in mind, I think I'll generally follow the WestfieldMX5 guide for 90-93 MS3X: 90 ? 97 MS3 | Frank's Westfield MX5 90 ? 97 MS3 | although I will look into it a little further to see if there's anything in particular to add or remove for my particular setup.

Just thinking out loud here, I'll post back after the holiday when I've got this thing in my hands. Cheers, guys.

Follow that guide but don't put the connector in the case it's annoying.

Main board is ridiculously simple with the 3x

Yep, that's what I'm realizing now, definitely the way to go like you said. And yes, doing a standard adapter harness, not the weird pnp-plug thing. Thanks for the input!

"weird pnp-plug thing" = DIYBOB?

I was talking about the part of the Westfield MX5 guide where he incorporates the OEM ECU plug into the ECU case, rather than using the db37 and building an adapter harness. 90 ? 97 MS3 | Frank's Westfield MX5 90 ? 97 MS3 | That part of the guide, I'm not following. I actually picked up the 64-pin plug and a breakout board for it from here: https://www.tindie.com/products/russ...ctor-bare-pcb/ So I'll be doing a diy-DIYBOB, essentially. I can build my own box for that.

Success! It works!! I got the 1.6 running on the MS today. It actually worked really well. I borrowed this guy's tune: https://www.miataturbo.net/megasquir...-signal-83789/ (thanks mkrazit!) changed settings to narrowband and batch injection, unplugged stock TPS, ran the MAP line, and it fired up on the first try! I didn't try to drive it w/o the wideband installed, but all the inputs seemed to be working properly, as far as I could tell. I'm super happy it worked out so well, I took my sweet time putting everything together.

That was the hard part of the project, tomorrow the 1.6 will be out!

This is usually frowned upon...

http://vignette2.wikia.nocookie.net/...20130110063433

But hey at least "it's running" right?

Well, the extent of me using it was idling in my garage for 5 minutes. It was nice to know the ECU I built is actually functional before I add the huge unknown of a new engine. Just thought I'd share what I did should someone else have the same questions.

Thanks for everyone's help though!

A basemap could of provided the same results with less risk.

Glad you're making progress!

So, update time. VVT motor is in and hooked up. Haven't been able to get it to start however. I used DIY's MS3-pro 2001-2005 base map and adjusted all settings and I/Os to suit my application, to the best of my knowledge. While cranking, tunerstudio wasn't showing RPM or RPM sync. I changed cam input to MS3x camin, but how do you check the status of the crank signal? I can't find a reference to it anywhere in the software.

Unfortunately I wasn't able to record a log - after about 10 tries it decided to stop cranking, just a loud click from the engine bay. Changed batteries and no dice. Not sure what's up with that, called it quits for the night. Curious - will the engine crank without any ECU connected oncesoever?

I'll attach the tune file I'm currently working with; if anyone would like to take a look at it that would be great. Like I said above, the hardware ran the 1.6 without a hitch, and I followed the swap guide to the letter. Hopefully there's not an issue with my new wiring.

Are u using the Cas or the vvt motors cam and cranks sensor. Have u got it set up that way in ts. I have mine set like a 90 since I am using 90 cas. It's one of the drop downs in ignition I think. Can check laptop in morning.
No rpm no start.

Yea, I'm using the NB sensors and have spark mode set to Miata 99-05.

Did u check clearance on crank sensor. U using stock crank pulley or vvt.
Hook back up ground at trans to engine brace by rear diff?
The one in engine bay by brake prop valve?

I haven't touched the crank sensor since it was running in the donor car, but I measured the gap at ~.031", within .020-.059" range. Using VVT pulley and toothed wheel, never separated them when pulley was off for timing belt.

Grounds are all hooked back up. Both cam and crank sensors show continuity to ecu and ground, and receive 12V, so new wiring should be ok. What else could cause no reading from either sensor, when it read the 1.6 CAS fine?

Take a composite log and post.

Composite log is coming up completely empty - no data recorded. I recorded a normal log, not sure if that is helpful at all.

Have you ever done a composite log? I remember it being kinda weird when I did it first time.

Double check the wiring to your sensors, do you have them hooked up correctly?

Cam sensor dead?

You're right about composite being finicky. Messed with it some more and gave it 10+ sec before cranking and got some data to show up. The first log is near 10 seconds of cranking, the second is a shorter crank that also displayed the attached plot in tunerstudio. I also removed the cam sensor and tried waving a piece of steel in front of it in various patterns and got plots to show up that seemed to resemble what I was doing (third log). So the cam sensor should be good.

I suppose I could remove the crank sensor and do the same? I've triple checked my wiring and it's all in agreement with the swap thread.

Post pics of all of em, on my phone so I can't see the logs.

The picture shows 1 spike on the crank sensor when there should be way more. Your cam signal looks fine.

It should look more like this.

https://www.miataturbo.net/attachmen...ine=1453081310

Is the blue line the crank sensor? The other log looked about the same.

I took another one of me waving a piece of steel in front on the cam and crank sensors. I got no response from the crank sensor, and still got response from the cam sensor. But, every time the plot refreshed, it showed the blue spike at the very end, so I guess that spike is just an artifact or something, not originating from the crank sensor itself?

I'll look over my wiring again. I was able to measure continuity from the sensor connector over the signal wire to the ecu connector last time. So either the sensor that ran the car a month ago went bad, or something is wrong on the ECU side.

(pic is me waving steel in front of cam sensor)

Found it! R56 was adjusted way wrong. I had dialed in 6 turns CW, but I measured only 1.1V at top of R54. Must have turned it way too far CCW initially (mine never clicked at the end of travel). Turned it in until it read 2.75 volts, and it's show crank signal and sync during cranking! Now the battery is dead again... Will attempt to start very, very soon.

Good. I was going to suggest that next if all your wiring checked out.

Thanks so much for all the help man, really appreciate it.

I finally got it running today. Had to switch ignition capture to falling edge. Now it starts and idles pretty well on the DIY Autotune base map. Timing syncs up nicely and sensors seem to be reading correctly, but it's running really rich. In the 11 range idling and nearly pegged at 10 during an attempt to drive, not driveable at all. Not sure what's screwy about my fuel settings, or if the DIY base map is really that bad. Had req_fuel set at the calculated 11.6, I guess I could start by decreasing that. Or if someone wants to throw me a decent tune for a stock vvt, that would be pretty sweet.

Either way, super happy it's running. At least, I was until a fuel line started spewing at the end of my driveway and it died, lol.

Off to do more reading.

Make sure your o2 sensor is calibrated. Then it just needs tuning. Base maps are specifically meant to be rich and safe.

Gotcha. Bought Tunerstudio and autotune is cleaning up the base VE table pretty quickly. Then I realized the kpa range is only 25 to 100 kpa, and trying to get up to speed it is just sitting in those 100kpa cells throwing AFR all over the place. What is a more reasonable range for N/A, 20-200? 250? Revving at idle spikes it up to 150kpa easy.

Thats impossible. 100kpa is the max you can have for an N/A car.

Duh, atmospheric = 101.325kpa. I've been on winter break too long. Well, that suggests vacuum leak or incorrectly calibrated MAP sensor. Will figure that out now. Thanks lol.

Edit: wrong MAP sensor selected. Oops!

Edit 2: Wow! I'm an idiot! The incorrect map reading was what ruined the tune. I reset the VE map and it is running much, much better to start than before. Stable idle and good tip-in right off the bat. Autotune is richening it up at high KPa so I'll add some fuel manually to that part of the table so I don't go exploding my engine before it can make corrections. Suddenly I'm liking this car again!

Well, the car is running pretty well now! Autotune dialed in the VE table pretty quickly. Only a couple small issues are really standing out to me at the moment. It tends to stall coming back down to idle immediately after a cold or hot start. Also need to find a frequency that doesn't make the idle valve buzz. AE needs some tweaking, blipping the throttle above 4k causes it to bog momentarily before it catches and revs. TS also is intermittently showing VVT1 error, so I'll have to look into that and see what's causing it and if VVT is even working currently!

I'm in the middle of the snowstorm currently, so the car is stuck in the garage for at least the next month, before I can do any more adjusting. Thanks again to aidandj and everyone else who contributed for helping me out! I met my goal of getting this project completed over my winter break. Can't wait for track season to start!

Set your min/max cam angle to a broader range. Not sure why this happens on some cars but I've found it gets rid of the VVT error.

Are you using closed loop idle and initial value table? If it's dying when cold, maybe your initial values aren't high enough at cooler coolant temps. Also what's your dashpot? TS likes to ignore the dashpot every once in a while, so I like to set it to ~.8% and add anything else to the initial value table. Let it idle in your garage as it warms up, and write down what percentage it's idling at for your 5 coolant temp rows. Once you have these values, enter them in for your target rpm. Don't forget your target RPM warmup curve. Then enter values ~1-2% lower for a higher rpm, because if it exits CL idle at a higher rpm you don't want that same value when it reenters CL. Same with lower RPMs, it was apparently not high enough, so enter values ~1-2% higher.

Once you have these numbers entered in, just do some driving. If you find it hangs high before returning to target idle, select the entire table and take 1-2 % out, opposite if it hangs low or dies. Take a few days to test it while it's cold to make sure it doesn't die, then do some hot tuning this summer in the higher temps.

You gave me too much credit! That tune wasn't too far off from Westfield Frank's basemap, IIRC. I can understand why you borrowed it (I didn't find much searching for 1.6s running MS3X either) and glad it helped out. I won't lecture, I assume you know the risks of using others' tunes...

From reading your posts after swapping in the BPZ3, it sounds like you're finding your way around TunerStudio despite a short learning curve w/ the 1.6 before the swap. Some of what you mention in Post #38 sound like idle valve and closed-loop idle tuning opportunities, assuming your idle fueling, ignition timing, and idle valve DC are set right to begin w/ -- DIYAutotune has a good tech article on this. Mine is put away for the Winter, but I had been reading through this blog for a simpler, expanded approach to aspects of tuning, specifically closed-loop idle tuning lately.

EDIT: I would echo Curly's above post on tuning closed-loop idle.

^ Yep I was just looking for something to confirm functionality of the new ECU. Start, idle, look at shiny dials moving around, remove engine. I did look through it before use. Unfortunately Frank's maps are NLA on his site.

Thanks for the tips guys. The base map was using open loop idle, so I'm going to have to record some duty values and set that up from scratch.