Ok guys, I am trying to figure out this Mega Squirt 2 ECU for my 2000 miata. This engine is currently completely stock and has AC. I do plan to turbo it soon but want to figure out the EMS first to simplify things later.

I have read and tried my hardest to understand all of the stickys. I have also tried to search out information that i couldn't figure out for my self. Unfortunately i still have a few questions.

First off, this is the list of components that i have come up with that i think i will be needing. Is there anything that i am missing?

-MS-II Engine Management System w/PCB3 - UnAssembled Kit $247.00
-Jumper 10-Pack $7.00
-JimStim v1.4 MegaSquirt Stimulator w/ Wheel Simulator Unassembled $59.00
-MegaSquirt Tuning Cable (DB9 Straight Thru) $5.50
-Innovate Standalone Gauge Kit w\ LC-1 & G3 Analog Gauge $289.00
-MegaSquirt Stimulator Power Supply $7.50
-Lead Bending Tool $5.50
-PCBv3 and v2.2 -- Relay Control 'ModKit' $5.00
-PCBv3 and v2.2 -- Boost Control Mod-Kit $7.00
-PCBv3 and v2.2 -- Pullup Resistors 'ModKit' $1.60x2
-250 pc Cable Tie Assortment $5.50
-MegaSquirt Wiring Bundle - 23" Long $12.00
-GM Open Element IAT Sensor with Pigtail $22.25
-PCBv3 -- PWM IAC Valve Control (TIP120) 'Mod-Kit' $7.00
Sub-Total: $682.45

Second, i would like to leave the stock wiring and ecu as unmolested as possible. I would like to run the MS as a standalone, but would also like to be able to switch back to the stock ecu if i need to.

Third, i am not sure what is needed to maintain control of the stock alternator, AC, and VICS. I don't really understand the stickys that address these issues. Perhaps i should just build the MS first and worry about these issues when i get to them.

Thanks for your patience,
-Jared-

 

Can't say much now due to time constraints, but I'll help you more later tonight. I suggest building a standalone setup myself. Simpler and better IMO. AbeFM has done a MS2 standalone and so have I. Research his name here too and you'll find some various info you might be looking for.

Also, once you put bigger injectors the stock ECU will no longer run the car. I built a parellel setup and now I'm standalone. Most start out parallel cause it's fail safe, but then realize it's not needed and they go standalone. Or just do parallel to let the stock ECU do idle, alternator, etc, but it will still not run the car on its own without swapping back to stock injectors.

 

I really don't want to run a parallel install, i just want the ability to switch back to the stock ecu while the engine is stock. Since this is my only mode of transport, I think this would really help me while I am still figuring things out.

 

For VICS, you will need one additional Relay modkit, and a 12v SPST automotive relay. This will be configured to operate within a certain range of RPM (I can't remember it off the top of my head- it's in a post somewhere) to open and close the VICS solenoid when appropriate. It's pretty simple.

For alternator control, you need the Mopar part that Abe refers to here: https://www.miataturbo.net/forum/t21621/ Alternator control does not interface to the MS at all, it's completely standalone.

For A/C, you'll just need a diode and some jumper wires. Again, this is independent of the MS. Ideally, you'll also modify your stock purge valve to open when the A/C is on, to compensate for idle droop and prevent stalls. I wrote up the NA version of this in my AC FAQ, I probably need to do an NB-specific chapter for that as well.

One alternative would be to do what's commonly referred to as a "Boomslang" install, after the company by the same name that builds wiring harnesses. Basically, you need to obtain a stock ECU connector, and use it to build an adapter harness. One end plugs into your factory wiring, the other into the MS. So to remove the MS and install the stock ECU, you just unplug the boomslang from the factory harness and plug the stock ECU in. Here's a picture of one that I build for an NA. The wires that are coiled up go to non-factory functions (EBC, WBO2, GM IAT, etc.) The yellow connector on the right was obtained by cutting the stock connector off of a dead ECU, though you can also buy these from some online vendor that's referenced in Brainey's big FAQ:

 

Im running MS-II v 3.0 EDIS with relay board and fuse block on my 90 1.6 with ITB's and is a complete parallel install. It controls spark and fuel only. It has its own independent set of sensors (MAP, IAT, TPS, CLT) and is not tapped into any of the cars factory wiring. The factory ecu controls the IAC valve and I enjoy completely stock idle from warmup, idle up when a/c switch is pressed to moving the steering wheel left to right. I modified another injector wiring harness to work with MS and kept the original one in case I decide to go back to stock. Havent had a problem in the 1 1/2 yrs that Ive had it.
There is an advantage to letting the factory ECU do what it does best and let MS control spark and fuel.

 

And admitedly, I'll be doing someting similar soon. I removed the stock coolant sensor and now I have no guage... And had other problems as well like fans running all the time. So finally I plugged the sensor into the electrical connector, but I still don't get a reading on the gauge since it's not installed into the cooling system anymore. Gonna add it when I do a reroute and basically do what you're doing. Let the stock ECU do idle and run my coolant gauge, tach, etc, and let MS run spark and fuel, and for the same reasons as you mention. Separate systems 100%.

 

I'm running parallel and while it works pretty well, I'm going to redo my wiring this weekend. I'll still be parallel but I'm going to use Jason's Schmitt trigger input circuits w/o pullups instead of the current transistor circuits.

If I didn't live in California I'd go standalone.

RDSnake, how do you control idle w/ a stock ECU and ITBs?

 

ecu is still connected to IAC valve -->IAC valve is bolted to an IAC Block (Fujiracing part)-->Connected to vacuum log-->Individual Runners.

 

Thanks for your help guys.
I just made my order today.
I will try to keep a light update as things progress.

-Jared-

 

Any thoughts yet on what your going to do for crank and cam signals? There is Abe's reverse engineering of the stock ECU, Jason's Schmitt trigger alternative of Abe's circuit, 97 or before cam sensor, or a toothed wheel like RdSnake and Pat. I don't know of anyone that has had luck with the circuit on the MS2Extra page but it's an alternative, too. I tried the VR circuit about a year ago for the crank signal and never got anywhere. I got the car running once with it but the signal looked like crap on a scope and the car would barely idle.

MS2-Extra Miata Manual

 

i am looking at buying the components for the "boomslang" style harness. However all of the distributors have a minimum order of $35. So from the looks of it i can get the parts for one NB harnesses for about $16.32 + shipping.

To prevent money from being wasted, does any one want to go in on an order with me for boomslang parts?
64 Pin Male connector (174518-7)------$5.66 ea
26 Pin Female connector (174516-6)----$1.13 ea
22 Pin Female connector (174515-6)----$1.08 ea
16 Pin Female connector (174514-6)--- $0.80 ea
.040" Contacts (175061-1)-------------$0.125 ea
.070" Contacts (173716-1)-------------$0.045ea

-Jared-

 

Good question Arga,
I was under the impression that the MS2 was able to be programed with the NB CAS.
How do you have yours set up arga? :edited: duh parallel with stock ecu

Since i have no answer to this, perhaps someone else could shed a little light on this situation.

 

The MS2E software can handle the 99+ crank and cam signals. Getting a clean signal to the software seems to be the challenge.

I'm currently using secret option 'D', a simple transistor isolation circuit. I'm running in parallel so the ECU handles the 5v pull up. It's worked well for me but a few other people have tried it and all of them have had trouble with dropped pulses. I'm currently redoing my wiring and I think I may try Jason's circuit instead. I can always go back if it doesn't work for me. NPN switching transistors are $2 for a box of 15.

 

A crank trigger wheel has an advantage of expandability. The future of megasquirt will bring us sequential injection, individual spark, etc. My prediction is the combination of crank trigger wheel (crank input) and 1.6l CAS (Cam input) would be the setup for the future for us.

 

Well that was fun! Jim stim finished, now it is time for the MS2

 

Ok, so i have a few questions.
1. do the jumper settings for tach and ignition mentioned in brainy's sticky work for a 2000 miata and a MS2?
2. Does the Q7 to Q4 swap and mod listed in the same post work successfully for fan control in my application?

i am sure i will have more questions soon as i am knee deep in this thing.

Thanks,
-Jared-

 

ok, screw those questions. Since a picture is worth a thousand words... this is what i have so far.
-along with the jumpers from Brainy's build instructions i have one relay hooked up for the fans
-how do i hook up the relay for the VICS
-there is no rpm value reported in megatune
-I cannot get my o2 to work in megatune
-I was only able to get MS2-extra 1.0.2 to flash to the ecu and run in megatune

 

ok switched the TSEL to OPTOUT and now i get a rpm reading (needs tuned badly)and a o2 reading.
-What firmware do you guys recommend i flash to the ecu/ can you post it's location?
-i am having a hard time setting up the tach/ignition settings in megatune, got any recommendations?
Thanks
-Jared-

 

You'll definitely need to install MS2/Extra 2.0.1 to get this working. The 1.0.2 release does not support the NB ignition settings, while it's built into 2.0.1.

 

i am having a hard time getting MS2_EXTRA 2.0.1 firmware to flash to the ecu. I get an error code at 40%
ERROR: Timed out reading response, 0xE0
Elapsed time: 7.58 seconds
ERROR: Timed out reading response, 0xE0
Elapsed time: 13.88 seconds

Any ideas?
cheers,
-Jared-