My MS install
 

I have MS working on my 90 Miata/MX-5, running fuel, spark and idle control. I have been asked to do a bit of a write-up on my install so here goes.

I purchased a MegaSquirt-I Programmable EFI System PCB3.0 - Assembled Unit from www.diyautotune.com. My plans were to run my car on fuel and spark and my research pointed me towards running MSnS-Extra which means that a MSII wasn't really an option.

In the attachments below is the pinouts that I used to connect the MS to the OEM harness. I used the wiring diagrams from http://www.madracki.com/miata/wiring.html which I've found to be much more accurate than the Haynes manual.

I had to mod my MS board three times;

1) To get the CAS signal I followed the instructions on the diyautotune site here
This worked without any problems and uses the connections shown in the pinout attachment.

2) To get spark I followed Nate Sully's instructions from his success page on the MS forum here
To get the Coil A output to pin # 29 on the DB37 I ran a jumper from the R26 resistor to IAC2A near the DB37 connector. I ran the Coil B jumper from R29 to IAC2B for the # 31 pinout.

3) The last mod was to get the PWM idle working. I followed the steps in the MegaManual for the PWM idle valve. I installed the TIP122 (which needs to be purchased seperately) onto the proto area and ran jumpers to the Q4 connection as shown in the MegaManual. I also re-used the diode that I removed (D1) from the board to go across the wiring at the idle valve connector in the engine bay.


I used the table generator in MegaTune 2.25 to get a VE table set up and that ran really well from the word go. The spark table was a lot more fun to get organised. Flyin Miata have a page of ECU defaults for the FM Link on their Product Support page. I had previously downloaded their guide "ECU tuning 4.3" which I then used to find where the spark table was in their defaults and I used one of the pictures in the guide itself to find the rpm and MAp values for the spark advance settings. I also had to divide their spark figures by 4 to get the 'real' numbers that I needed for the MS spark table. The Link spark table is a 6 x 16 setup so I had to use a bit of maths to fill out the MS 12 x 12 table.

For the spark settings in MegaTune I used Nates figures from his success page and my car literally started at the first go. It helped that the ambient temp was 37 C that day as the cold starts aren't usually too much fun. They certainly haven't been that good since....

Now I'm in the process of tuning the MS, working on the cold starts (getting better) and getting the fuel tables where I want them to be (which is a little difficult since my LC1 is busted and I'm back to the NB O2 sensor and a calculator). I haven't had to change the spark table at all so I'm really happy with the FM Link settings and my math abilities (thank goodness as I'm a math teacher).

The car is going great, and with each tuning it gets a little better. In the next few weeks I'm getting a 260 duration intake cam fitted and them I'll get to play with it all over again.

I guess the overall thing that I've learned from the whole process is that it really isn't that hard to get a miata working with MS provided you're patient and prepared to learn heaps.

If anyone has any questions about specific details of my install I will do my best to answer them. In the mean time get your MS and start soldering!!
Steve

Hey Aussie Driver that was me that msg'ed you on miata.net! Thanks again for posting all that information, thats really awesome of you. :bigtu: As you can see this forum is kinda slow, this is a small forum but its growing all the time and the memebers are cool guys. It started out as a greddy turbo forum but now has a pretty cool DIY turbo forum too and it would be great to get MS goin on here.

Anyways about the questions.

On the pinout what years will that work for?

Also how hard was it to modify the board from when you got it from DIYautotune?
Smilies

that's awesome!

was following your thread on m.n.

i joined the msefi.com forum but i was still trying to decipher all the acronymns and refamiliarize myself with some electronics and EFI basics

Yup I saw his post on miata.net and asked him if he could post some stuff over here. I hear ya on all the acronymns for example:

Ok sorry I am so dumb but could somebody explain what these terms are so I can sort them out.
R26???
IAC2A???
IAC2B???
DB37- This is a 37 pin serial cable basicly right?
PWM idle??? (I am sure the megasquirt manual will tell me, I just have to go look.)
TIP122???
Sorry I am so dumb i am going to look some of these up in google.

EDIT: Oh ya, how hard do you think it would be to make a spark table for a turbo car?

kick ass, thanks for the info!

google won't help you much ;) msefi will.

IAC2A and B are just the spare wires that could be used to control an idle stepper motor, they are not used on a miata. so, they are put to use as wire to run the ignition output (ignitor on 1.6 and coils on 1.8) R26 and R29 are wired to these directly to fire the ignitor/coils.
just read this thoroughly a few times and compare it to a picture of the board on the megamanual, and it will become clear.
http://www.diyautotune.com/tech_arti...alon_laser.htm

oh yeah and no it is not difficult to do these board mods, you just need a fine tipped low watt soldering iron
I've done all my mods and am looking forward to resuming progress on mine after the autox tommorow (converted back to stock to run in STS2)

By the way, thanks for coming here and helping out aussie!

The pinout that I posted will work for all NA's with the DB37 connections. Just double check the link to http://www.madracki.com/miata/wiring.html for your car's specific wiring diagram to make sure that the OEM wiring goes to the correct places.

The board is really easy to modify to get the spark, CAS and idle control working. You will first need to remove the capacitors C12 and C30 from the board (refer to the V3.0 Board Components picture that is in the mega Manual here) and I removed D1 and replaced it with a jumper (keep D1 as you will need it later for the PWM control). This will enable the board to control spark as well as fuel.

Then you need to get 3 1K 1/4 watt resistors to complete the board mod for the CAS. Refer to the picture here which shows the steps better than I can explain them....

The spark output mods are covered in my initial post. Just make sure that you solder the jumpers to the heat sink side of the two resistors R26 and R29.

The TIP122 is a beefier transistor which is able to handle the PWM outputs. I have no idea what PWM actually means and I'm not at all concerned about not knowing. It's the idle control that we have on a MX/Miata, we do the PWM mods and it works. That's enough for this Aussie!!!

Steve

Getting a spark table from the FM Link isn't too difficult.

Click here ECU Defaults, select your configuration and save the file. Then download the Link Tuning Manual.

The picture on page 23 of the manual gives the MAP values and the ignition zones (rpm values) can be found marked in the table on page 40.

Then just grab a calculator, find the half way points between the given MAP values (pg 23) and include these new calculated MAP values in your MS spark table along with the given MAP values. Then calculate the half way point between the spark advance figures (remember to divide each one by 4 to get a 'real' value) for the given MAP values to fill in the blanks for your newly calculated MAP values for each rpm. It sounds difficult but if you do it step by step then it's not too bad.

Steve

Thank you for clearing a lot of that up :bigtu:
Looks like I can go here http://www.flyinmiata.com/support/defaults.php?choice=3 (the values for a turbo 1.6 with 440cc injectors) to build a spark table?
what is the zi numbers about? Imma look at the manual from FM?

PWM = Pulse Width Modulated, there are a couple of pages on it in the Mega manual.

What transistor did you replace with TIP122? I have never heard of anyone using the PWM on a Miata in the success stories on MSEFI.net. I am assuming that is pin 30 on the DB-37 is, correct?

Would you mind posting your tables?

Steve, you have been an invaluable asset to this forum, thank you for spreading Megasquirt disease!:bigtu:

The TIP122 replaces Q4. The PWM idle uses the FIDLE output on the DB37 (# 30).

I'm still playing with my settings but the attachments show what I'm doing at the moment.
I have just taken these off the MS after mucking around with the idle for about 30 mins this evening. I haven't been able to get a decent idle out of it using the "Closed loop only" mode, but I had my car idling between 910 to 940 rpm with these settings. I have changed the idle control on the throttle body so many times that I've lost track of where it was initially set, but these settings work well for me. I have deliberately set the idle higher then the factory settings so there is a little bit of leeway when the lights etc are used and the load on the engine is just that little bit greater.

Steve

NOTE: I have had to adjust the slow idle temp so I could get a more reliable hot start. Instead of 50, it's now 70. If you use these settings, you may also want to lower the fast idle temp.

whats the best way so splice into the stock harness and how easy is it to reverse it? (I think it would be best to use the stock ecu to pass smog.) You think its best just buy that wireing harness they have on DIY auto tune? Myabe Just run wires for the injecters, cas and intake temp sensor (I want to ditch the afm!) Have you been able to eliminate the afm/maf? I really want to be able to not use that hunk of junk.

I just used standard electrical connectors to splice in my MS harness. Basically I cut all of the necessary OEM wires, put a male spade connector on the wire end going towards the ECU from the engine, an insulated female connector on the ECU end of the wire and another insulated female connector on the MS harness. That way a full MS removal takes less than 5 minutes. For the wires that the factory ECU still needs like power and the grounds, I used a piggyback connector that allowed the MS and factory ECU to both be connected at the same time.

It's much easier to use the OEM wiring than run your own loom. Besides the OEM wiring is already properly fused so it's much better protection for the MS if anything does go wrong.

I have eliminated the need for the AFM but it's still currently connected for the moment as the AFM holds up that side of my CAI. (When I get my Racing Beat Type 2 nose I'll re-do the air intake so it comes through those great big holes in the front of it.)

You have two options if you want to get rid of the AFM.

1) Disconnect the AFM and run a jumper from pin E1 to pin Fc in the connector. This will keep the fuel pump on while ever the ignition is on.

2) Buy a heavy duty automotive relay and connect this to the MS (pin # 37 on the DB37 I think) so that the relay will send +12V to the violet OEM fuel pump wire when the MS wants the fuel pump to work.

This is because the MS controlls the fuel pump by grounding the connection, but a 1.6 MX/Miata ECU controlls the fuel pump by sending it +12V. So basically you want to turn the ground signal into a +12V signal. The relay will do this provided you wire it up the correct way.

Steve

thanks for the info! I still have more questions haha I am sorry.
Ok when it comes to the connectors you used in a dummy when it comes to knowing what they look like. (Sorry I am so dumb)

Did the piggy back connectors look like this:
(Do you just strip a section of the wire and clip this badboy on or something?
http://img203.imageshack.us/img203/6...ggyback1io.gif

For the spade connectors did you use ones that look like these?

http://img203.imageshack.us/img203/931/spade3vb.jpg

And is this the automotive relay you are talking about? If so I am unsure on how to wire it :gay:

http://img203.imageshack.us/img203/8106/relay9fk.jpg
I am betting its easyer and cheaper to just jumper the two pins you were talking about. What method would be best to do this and still be quickly reverseable? I slight worry is will this keep the fuel pump always on when the key is on the 'on' position so that in the case of a wreack it will still be on? I know its slight but I dont want the fuel pump spraying fuel if I get into an accident and a line gets cut or something stupid.

Also did you have to soder the wires together or not? I am assuming not.
I want to put the MS in the glove box so I am sure I will need a little extra wire to connect everything. What guage wire is needed? Is there a special automotive grade or anything?
The reason I wanted to use my own harness is for some reason im leery about cutting into the stock harness :gay: . Using the stock harness sounds like it would make the install a an easy and quick process. How long did it take you to wire it up?

My last worries is getting it working is tuneing it properly (and not screwing up modifiing the board). (I will be using an LC-1.) My car is currently turbo and im using a fuel pressure regulator to provide enought fuel but I am thinking of swapping in my 315cc injectors. It sounds like it would make the tuneing process easyer without using the FPR. Also is the spark table and how much I am going to have to retard in boost to prevent detonation. I will proabably need my hand held for this. FM's table looks like voodoo to me. I was a substandard math student but I am sure I could workout the method you stated if I could understand whats going on in FM's charts. I might just do fuel first. No timeing control makes the car a dog in low rpm becuase I have to retard the base timeing 4 degrees right now. (6btdc)

The laptop I plan on using is an old pentium 1 300mhz with 32mb of ram running win98se. I dont know if this is enough cpu power but it seems to start the megatune software just fine. The laptop was free! :bigtu: Sorry for yet another huge post haha.

Mike, the only dumb people are the ones who don't ask questions.

Those blue connectors in your picture are just like the ones that I've used, but the female ones are insulated all the way to the end of the connector. The piggyback connector is perfect!!!

For my install I went to my local auto store and bought a heap of automotive wiring. I thought that I'd be smart and get the same colors as the OEM wiring. What I did was to use two lengths of wire to try and replicate the OEM wire. For example the OEM idle control wire is Blue-Orange so I used a bit of blue wire and a bit of orange wire, twisted them together, stripped a bit off both ends, soldered them together and used them for my harness. I soldered one end into the DB37 connector and the other end went into a female connector and I crimped the connector onto the wire.

Once I did the connectors for the OEM wires, it was a simple plug-and-play to install the MS.

I have used a different relay for the fuel pump but as long as that relay is rated for automotive use you should be fine. As for relays themselves, go here and have a read of that article. They explain it better than I could.

As for getting it working, most of the MS settings should be the same from my NA to your turbo with the exception of the boost stuff (obviously), the fuel table and the spark table. An easy way to get a starting point for both the fuel and the spark would be to use Nate Sully's msq from his success page. It's not in the correct format for the latest version of MSnS-E 029h/i but if you download version 027 of MSnS-E you will be able to open his file and do a screen dump of his settings. Then re-load the newer version of MSnS-E and use his settings for your fuel, spark and boost. Don't use his Req-Fuel settings or his injector settings as Nate is using different injectors.

If you have any problems with it, post them here and I can try and talk you through them.

Oh and my old laptop is a slow old heap of crap too but it works just fine with MegaTune!!

Steve

This probably reveals my ignorance of MS and standalones/tuning in general, but what sort of parameters are you manipulating to improve cold start behavior?

Ok Got ya on the connectors I understand that they need to be insulated compleatly on the female end. When you attached the wires to the connectors did you soder them in place?
Thanks for the link I understand now how relays work. its 2 independent circuits. 1 of them is an electro magnet that pulls down a switch that will compleate the other circuit. So you would wire it up so the MS 12+ (on pin 37? Right) would complete the electro magnets circuit and then that would turn on the pump?
Ok I made a picture to see if I am remotely right. Take a look

http://img142.imageshack.us/img142/9...laypump5up.jpg
Assuming I made this right can you get all these power sources from existing wires in the car or will I have to run some for the fuel pump? What does the relay you are using look like?

Ha just last night I was wondering how to get nates file to open right in megatune. I wanted to take a look. Is there a different version of megatune for the Extra firmware or something? becuase when I loaded that msq file it just had wacky settings in the VE table.

It's just playing with the cranking settings. I've been able to get first starts from mine for the last few days.

Mike your relay connections need to go the other way around. The MS pin # 37 is ground and your ground next to it should be +12V. Then your Ground? should be +12V and the top one will be grounded via the OEM wiring.

I used my +12V from the radio to source the power from for the relay. My relay looks a little different but they do the same things.

whoops I screwed up! I figured that pin 37 would in the 12v. I understand where I went wrong at the top the fuel pump ground is always connected and the 12v+ is switched on to turn the pump on, right? And the MS turns the pump on by creating the ground to turn the pump on and the 12v+ is always connected?

here now does this corrected one look?

http://img301.imageshack.us/img301/6...umpfixx1lp.jpg

So do you get Both 12v's from say the radio? If you have an aftermarket pump will this create an issue? A picture of what it looked like would really clear it up haha. Can you power guages and the fuel pump all off the radio's 12v?

I'm not having any problems using the switched 12V going into the radio for the relay. But I took the radio out a while ago so the 12V wasn't doing anything else. Your relay setup looks good to me!!!


MegaTune 2.25 should work with most of the recent editions of MSnS-Extra. You need to install MegaTune 2.25, then go to where you unzipped the MSnS-E file and run the "edit settings" DOS application to change the Mt settings to run MSnS-E as the default (also do youre wideband sensor there as well). Save the file that you have opened.

Then run the "copyini" DOS application to copy the s19 file that is in your MSnS-E folder into MegaTune 2.25.

After that, you should be good to go.

Just remember though that if you are creating your own msq file, open MegaTune and then open the default msq file that is back in where you unzipped your MSnS-E file. Then make your changes to that file.

Steve

Steve,

Do you live in Brisbane, and if so what is your favourite beer? :D

This MegaSquirt stuff looks great, I'll be sure to consider it when it comes to getting aftermarket management. Do you have any pics of the mods you've done to on the PCB?

Cheers,
Tim

No mate, unfortunately I'm not a Brisbane boy. I'm a couple of borders down from there. But if you're in the mood for a drive my favourite beer is Stella. Mmmmmmm beer......

The MS really is a brilliant little ECU. It does everything that I need, it's an amazing learning experience and it's the best bang-for-buck mod that I've ever tried.

The other MS install topic on this forum has pictures of the board mods that are required to get the CAS signal, the spark output and the idle control. Feel free to get in contact with me if you decide to go the MS route.

Steve

I spent a summer in Lismore back in 1992 at the University of Three Rivers, just south of Brisbane and the Gold Coast. It was my summer, your winter. I loved your country, Texans and Australians have very similar cultures, great memories.

Chris

This link might be of some value:
http://forum.miata.net/vb/showthread.php?t=16655

I'm thinking I'll buy both sides and create a short harness that plugs in where the stock ECU plugs in. From there it will have wires running to both the MegaSquirt and the stock ECU if it is retained. This means that I can revert back easily, and best of all I can do all the soldering at my desk!

Hey Steve,

On the DIYAutoTune site you mentioned it says you need (1) 1k 1/4w resistor and (2) 470 ohm 1/4w resistors, but you said you used (3) 1k 1/4w resistors. Should I just do as the site says or should I substitute the 470 ohm resistors for 1k ones?

Thanks again mate!

That's interesting. When I did the mod the diy site said to use 3 1k 1/4 w resistors. Now they seemed to have changed their mind..... Interesting.

I'm using the 3 1 K 1/4 w resistors and I haven't had any issues with my spark control at all. So I guess you could go either way.

I wouldn't mind knowing why they made the change on the diy site though....

This thread talks a little bit about the instructions changing:
http://www.msefi.com/viewtopic.php?t=18883

Edit: I posted this too soon, I realise you've read that since you replied to it too! :D

I like your method of piggybacking connections and having quick disconnects. I also plan on using this method. Out of curiousity where did you mount your MS? It seems like if it's mounted close to the stock ECU then your MAP sensor vacuum line is going to be pretty long (10' or so). I'd think this would cause troubles tuning. If you mount it in the engine bay the wiring seems like it would be considerably more nasty. Just looking for what other folks decided to do. I want to go full MSnS, and keep the stock ECU for diagnostics (emissions laws require me to have it).

Thanks,
Ark.

P.S. I'm Arkmage_Newbie around m.n

I can't recall where I saw a thread about long vac lines, but someone tested a really long line (20 metres or something crazy like that) and they said it didn't make any noticeable difference!

The line to the MAP sensor can be as long as you want it to be. I'm pretty sure that it was the guys from Flyin Miata who did the really long vacuum line experiment. I have mounted my MS next to the OEM computer. The MS and the DB37 jumper cable happily fit under the plate in the passenger's footwell.

And my car drives as well as it used to on the factory computer while using less fuel and sounding really cool on the over-run, so tuning isn't really an issue with the long vac line.

Sweet... good to hear. Now I just need to sell my van so I can buy the kit ;)

Hey Steve,

Just another one, I read through your thread again and I saw you've spliced the power wires so they run to both the MegaSquirt and factory ECU. Does the factory ECU need any of the other wires that the MegaSquirt uses, or are they simply cut?

For example do I run the tach and/or TPS wires to both the factory ECU and MegaSquirt, or do I just cut those wires and hook them in only to the MegaSquirt?

Cheers

The CAS wires are cut
The OEM coolant temp is shared
The OEM AIT is still connected
The OEM injector and coil wires are cut
The OEM grounds are shared
The OEM power is shared
The variable TPS is MS'd only the remaining ones go to the OEM
I've reconnected the fuel pump to the OEM
and I think that's about it.

If I've forgotten anything that you need then let me know.