Which MS do I want?
 

Now that the AU$ is almost getting to parity with yours, I'm pretty keen to pick up an MS before the inevitable happens and we're back to $0.70 US to $1 AU. My only issue is, I can't decide on what to get without putting myself too far into the deep end. I'm a mechanical engineer, so I've got a base level of knowledge for electronics, so I can construct a circuit from a diagram but won't be designing my own circuits any time soon.

I was thinking of getting an MSII a few months ago, but now that there's a couple of guys running MSIII successfully, I'm thinking of going in that direction. Given that I'm completely unfamiliar with Megasquirt, will I be biting off more than I can chew? And if I'm only chasing about 250hp, is the extra cost worth it? I definitely like the SD card logging, but I don't know if I need anything else MSIII offers.

Sorry for the noob questions, but there's only so much I can pick up from reading, and the insight of someone who knows what they're talking about is worth so much more.

TL;DR - Brain, do I want to buy an MSII or MSIII?

An MS3 ECU with Expander card will have a little bit higher upfront cost, but will actually be a less difficult ECU to assemble as most of the circuits you need come on the (preassembled) Expander card. The main board assembly would be greatly paired down; you really shouldn't need more than the power supply and tach input sections of the main board. All of the outputs--ignition, idle, injection (sequential), boost, etc are standard on the Expander. So my vote would be MS3.

Ben, you need to offer v3.0 board with just the components you need for the MS3 + M3X combo...since it's like 1/30 of the components of the regular kit.

Thanks for the quick replies guys. I've done a bit of reading on the MS3X card, seems like a handy bit of kit. Since the ignition circuit is pre-built on the expansion, is there a risk of frying the ignitor, or is the circuit similar to the inverted spark circuit that everyone favours around here? Can I change it to the inverted spark circuit if necessary?

For the time being, I just want to run my '93 1.6 in it's stock form. Will I need any extra modkits, or will getting the unassembled MS3 kit and the expansion card be enough?

Whereabouts are you Kain?
I'm in Sydney and could give you a hand at assembling/tuning if you want (and you're local).
I'm now running an MSII (prviously MSI) and could familiarise you with the functions if you decide MS3 they are almost identical.
Tuning will be your biggest challenge IMO the writeups around here are pretty much all you need to build the board.

I'm up in Brisbane, unfortunately. The actual construction of the ECU doesn't phase me, there's plenty of instructions (and I've read most of it at least once), and so long as I take my time and use my brain it should be fine.

Tuning will be the more difficult thing. I'm planning on keeping everything as stock as possible so I can swap the stock ECU back in if I need to use the car and the MS is not playing ball. If it gives me too much trouble, there's a shop not too far from me that has experience with MSPNP, so I would imagine that they could help out without too much trouble. I don't think it will get to that stage though, I shouldn't have any trouble figuring this stuff out once it's in front of me.

I've had a scope on the Expander's ignition output, but didn't think to look for this. It should have an improved ignition output that does not go high when loading firmware, but I've not checked it myself.

Yes, you should be good with an MS3 kit plus the Expander, but you'll also need to pick up a couple of resistors for the main tach input mod, and you'll want a db37 solder cup connector for the Expander so you can make a harness from it. Or we should have high quality premade Expander harnesses available in the next few days.

Right, I've just placed an order for an MS3 and MS3X. Now that I've thoroughly dropped myself in the deep end with an ECU that's not yet widely used, you may be hearing a lot from me in future :noob: Hopefully later on I'll be able to advise the next noob who wants to build an MS3.

Thanks for the help!

are you going to stick them on a PCB?

No, I figured that if I just sorta soldered them to the case of the stock ECU everything would be sweet? :loser:

Seriously, I got the whole MS3 kit, not just the daughterboard. If the kit is missing something as fundemental as the main PCB, I'd be worried.

Boy, this would be an easy question to answer if the schematics were available...

so the v3.57 kit?

Ahh, I didn't realise that there were multiple kit versions. It seems the only one on the DIYAutotune site that's sold as a kit is a v3.0. Is that incompatible with the MS3X?

No, either the 3.0 or the 3.57 will work just fine. Some of us (myself included) somewhat prefer the 3.0, as it contains a prototyping area.

The biggest difference is that the 3.57 uses mostly surface-mount parts and comes pre-assembled. Some folks fear working with surface-mount components, frankly I don't have much of a preference either way. The through-hole boards are kind of nice in that you can snake jumper wires through unused holes, but hopefully there won't be as much of that sort of thing with the MS3.

Well it seems that v3.0 would have been my preference anyway, I like the idea of having a proto area available. Also, not too keen on trying to use surface mount parts. Thanks Joe.

The circuit's on the board Joe. I just haven't scope verified it.

Yeah, I know. There's some mystery circuit on the board that I'm not allowed to see the schematic for. I'm supposed to just take it on faith that unlike the VR input circuit, the hall / opto circuit, the IAC drive circuit, the injector drive circuit, or the fuel pump driver circuit on the Rev 3.0 / 3.57 board, this one is actually well-designed and operates the way I want it to.

Nothing against y'all at DIY. I know this isn't your decision and you know that I love you guys. I'm just a little annoyed by this whole Vail of Secrecy thing. If somebody wants to clone the MS3, they're going to succeed with or without the documentation. Pisses me off that all of the legitimate users are being made to suffer for it.

Not to be a jerk, but do Motec provide schems for their boards? Haltech? Microtech? Assuming they don't, lots of people use them anyway and they work fine.

Honest question because I've never used them.

Ken

Do any of those companies sell their ECUs in kit form and expect the end-user to assemble and program them?

(Answer: no, they do not.)

I don't expect schematics when I buy a Panasonic radio. I do expect schematics when I buy one from Heathkit.

OK, I'll give you that for the DIY V3 board, but the MS3 is far less of a "kit" than the older offerings were.

It's potentially 3 surface mount boards (3.57 mainboard), 2 of which are connected by ribbon cables... not a whole lot of assembly there.

Again, I see your point, but B&G are fighting a very large number of pirates, and those pirates are having a definite effect on the bottom line for B&G. It's not just a few random people, there are people cloning and selling these boards and making a lot of money doing so. So I understand that they feel the need to do *something*. B&G need money to keep the project going; it's that simple. They really don't make much, if anything since all of it gets poured back into the project.

Not only that, James and I have spent a lot of time and effort (including convincing B&G that people want what the MS3 offers) to make the MS3 a good product.

Ken