Hey, I've been reading/hearing alot of good things on using the megasquirt system. HOWEVER, looking into it some...there are ALOT of options/pieces, etc that you can get with these. Can I get a simplified list of what the best setup for an s4 tII would be? Then I can narrow my research down quite a bit.
RS-Autosports seems to be a good place to buy everything you need...I just don't know what exactly I would need. Somebody make me a newb shopping list.

 

Seconded..

((thread jack))
or at least some threads on msefi.com that I should read. I know full stock ignition works... but you have to solder in some stuff to get the trailing to work, and i suck at soldering, but do you have to do that if you just want to use leading? Also maybe a primer on some aftermarket ECU generic things... like what you remove, what makes it easier... like the afm can be removed? and having an s5 full-range tps makes it easier? (so confused here) so basically maybe some good threads for me to read would be nice

 

Okay, Here's a hopefully helpful list of getting an S4 up and running, as I understand it.. Unfortuately, I haven't done a electronic ignition control module yet, so I can't comment on that, but it's the same basic setup, except you have to make that extra board.

Disclaimer: This may be completely wrong. If it causes your car to come alive and shoot you and everyone you love while you're sleeping, I cannot be held responsible. It may rape your cat, it may pillage the neighborhood. Again, not my fault.

Just a note, I'm NOT going to cover how to set up your megasquirt's software for rotary, as there is an excellent walkthough located at http://www.msefi.com/msinfo/manual/rotary.htm . This won't help you get it wired up, though

You basically have two choice for boards you can get. You can get the v2.2 board, or the 3.0. The 3.0 lists reinforced injector control components, so you have less chance of damaging them, as well as automatic fuses and better shielding for less noise. As far as I know, there are no drawbacks to using the v3, so get that if you can.

After you choose a board, you have a few choices for addtional components:

Stimulator Board - You HAVE to have this. This allows you to completely test your MS without actually installing it in a vehicle.. Using potentiometers, you can adjust things like RPM, TPS, Manifold Air Pressure, etc. You can verify that your megasquirt is working with this, before you wire anything up.

Flyback Board - This is a upgraded, "Heavy duty" circuit for the injectors. I'm not sure if this applies still to the version 3 board, it's VERY useful for version 2.. It allows you to directly run out to low impedance injectors, without using that distro block that's stock in S4s

Relay Board - This is a handy "remote" for the Megasquirt. Instead of having to run wires directly from the engine bay into whereever you mount your megasquirt, you can run wires into this. These feature fuses and full, auto-grade relays. A lot heavier duty power handling capablity, as well as convience of water-resistant components, making it perfect to put into you the engine bay.

Remote Board - Allows you to hook up a small "remote" to minutely adjust your fuel map, as well as get basic display such as AFR on a small LCD. Sounds useful enough, I haven't seen one in action yet.

just use the links off of www.megasquirt.info to purchase all the components for the board of your choice.

Now that you have your Megasquirt, and i'm assuming you followed the VERY easy to read step-by-step build guide, you're ready to wire it. Stay tuned in the next post.

 

When I first heard about Megasquirt I read for WEEKS on the msefi forum. There have been some big improvments in the last few months so you probably would have better luck digging around there.
As for what you need from the stock set-up. Injectors, throttle body, water temp sensor, air temp sensor and I used a TPS off a GM car from the junk yard.(made a simple bracket) The stock fuel system will remain pretty much stock(regulator etc). It will just be run by a different ecu. Most of the harness you will need can be pieced together from stock connectors or you can buy new stuff to leave your harness intact.
You can program the system to get readings from any sensor for temps. (stock GM Ford etc)
I havn't run my car on the system yet but I have used it as a data ac. system on a friends car.
I would start by checking out the "succes stories" part of the MS forum, everybody was very helpful when I built mine. But just like here, search first, I amost always found the answer I was looking for. When I didn't find the answer it was because I had one of the first MSll's sold to the public and it was a new problem.
One thing I found was it was trickier to order everything than it was to build it! And I had no circuit board experience.

 

heres a good list of parts.

do it yourselfer.

1 20 watt soldering IRON from radio shack.
1 big roll of rosin core solder. most regular solder works fine. 60/40 is what you want
1 tube of silicone rtv
1 9v ( if you baught the stimulator which is pretty much manditory if your building it yourself)
1 pair of needle knose pliers.
1 pair of small wire cutters.

1 db9 data cable.
1 computer(lol)


Before you go off and start building, you will also need to get this for when your done unless your like me and only plan to sell them for unltra cheap to felow rx7 guys.

a crapload of miscelanious wire that is different colors. ranging from 12 gauge to 16 gauge.
heat shrink. a soldering GUN. not an iron. it will just **** you off. some electrical tape.

from here you can pretty much pat yourself on your back depending on what your application is and what you want to run. some people even opt to buy an o2 sensor now since they think that stock one is poopies, which infact it is. poopies. sheer utter poopies from magical faries that come to haunt your tuning abilities. the wideband will help to defeat these pesky faries with its excilent bowstaff skills. ... herm... well... yeah. anyways


thats an overall parts list. i hope this gets sent to the megasquirt section of the forum.

 

Now that you have your Megasquirt assembled, you're into the fun stuff. The Wiring.

There is an AWESOME wiring diagram located here: http://www.msefi.com/msinfo/manual/mwire.htm

Print this out and bring it with you when you go to work on the car.

Now is the point that you wish you had a relay board, cause all you'd have to do is run a DB37 cable out to the engine bay. That wiring diagram is about all you need. If you have the relay board, you can run wires directly out from whereever you mount it to the sensors/injectors/etc.. If not, then you can either hijack the stock wiring, or make your own.

NOTE: You will want to print out the wiring section of your FSM. It will make your life INCREDABLIY easier to have this in print. Spend the money on paper and ink, cause it's worth it!


One good suggestion if you want to mount in the stock location, a great Idea i've heard is to get a junked ECU, and unsolder the big connectors to the mobo, then solder wires into the megasquirt. You now have a plug-and-play ECU, without hacking up the stock wiring.

Notes of interest in your car:

YOU WILL NOT BE USING YOUR AFM. let me repeat that, since that seems to be most peoples' first question (dunno why), YOU WILL NOT BE USING YOUR AFM. You can leave it in place, find a nice home for it, keep a door open, whatever.

The injectors should be wired up so that the primary injectors are on "injector 1", and the secondaries are on "injector 2". This is because the MS software has what's called "Staging", where you can set what RPM you want the secondary injectors to open up at. Very handy, and it auto balances, so you don't even notice when it does it. In my case I have mine at 3500RPM.

The Throttle Positioning sensor will make your life easier if you hook it up. It is NOT necessary to use. MS's primary acceleration sensor is the Manifold Air Pressure (MAP) sensor that gets embedded on the MS board. You run a vacuum line over to that, from where your boost sensor was stock. The throttle positing sensor (even a narrow-range one, like on NA S4s), will work great, without it, there will be a slight delay when you hit the gas, due to lag in the MAP. With a TPS (even narrow range), it uses that for instant notification of accelleration, but your fuel map is still based off of MAP.

Other things that you will want to hook up: Manifold Air Temperature sensor (on S4 NAs, it's on the driver's side of the throttle body, small cylinderical sensor with two spade connectors on it). Temperature sensor. There's a slight mod you have to do the megasquirt, which is detailed on the Rotary.htm page listed on the next post up. The reason the temp sensor is important, is that Megasquirt has the ablitity (just like stock) to enrich your car while it's cold, and lower the gas requirements as it warms up. Very cool.

Ignore the FAST IDLE solenoid. We have that thermowax thingie that will hold our idle up when cold. No need to worry about it.

------

Now, from what I understand, you S5 guys have electronically activated aux ports, we lowly s4 people have air pressure activated ones. for us S4 guys, I'm sure you know what to do to keep them functional already, since they don't pertain to the electronics at all, they're not being covered.

S5 guys, on the other hand, have to worry about the electronics (I believe). Please note, i've never gotten to play with an S5 engine with VDI. I really honestly have no idea, other than what I've observed online. If you use the Megasquirt N spark code (which you will want to do) Check out this page: http://megasquirt.sourceforge.net/extra/ It will tell you how to set up the MS for a RPM switch.

 

All good stuff...keep it coming.

 

Well, there's not really too much to it, other than that.. I mean, there's links to where to purchase everything, SirCygnus gave a good soldering supply list. The walk through is great for assembly, and basic setup, and the rotary page covers the rotary part of things. Life You should be able to get everything up and rockin', just by hanging out out in the Megasquirt section of this forum (under Engine Management), and the msefi.com (megasquirt's forum).


One thing I didn't cover is the igntion, andt hat's because I don't know what to do for it, but ti's discussed in the thread, over in the MS section of this forum . It doesn't sound too hard.

 

Nice info, this thread wins the internet.
Now on to my question, If i dont want to hack up my stock ecu, but still use that wiring... i can get an adapter thing like from here (very bottom: http://www.rx7.com/store/rx7/fcecu.html) and then just cut that wiring into the Megasquirt's input, that way if for some reason I need to use the stock ECU i can just reroute the pressure sensor line back to the original position unhook the megasquirt, and replug in the stock ECU?

 

Icemark or somebody else on the forum should do this and offer it as a service. Send them the parts, have them desolder/resolder. I think it'd go over well. I can solder like speaker wires and such...but, I don't trust myself at all on circuit boards. I think other's would agree.

 

Or just get a bad ECU and remove the connectors, then connect MS up to the connectors---much, much cheaper.

But yea the adapter connectors at the link will work too.

 

Just a helpful hint - the best solder you want is 63/37 rosinc core, also know as eutectic (sp?). There is no plastic state. This means that it goes directly from liquid to solid, so you don't get wrinkles and it just generally works better.

 

Haha yeah I thought about that after the fact... I can be a bit slow at times... even with 2 dead ECUs right on my desk lol
Sounds like this set up is pretty solid with a nice following, and from I can tell the software seems awesome too
Thanks for the info

 

Me, tofuball, and a couple of other guys are going to offer a plug-n-play in the stock ECU case option at some point.

A couple of additions/hints, and ignition info

I prefer the S5 wide range TPS for doing accel enrichments, but it isn't needed. I think having the TPS makes tuning accel enrichments easier. I also recommend getting a wideband O2 controller and sensor. You can tune by the seat of your pants, but once you have a wideband, and you know the AFR you're running at, you won't want to go back to narrowband.

Ignition: I made a howto that hopefully isn't that hard to follow.... I'm not done with it yet, but here it is. It assumes you've got a megasquirt and you've looked through the software a bit. It was also geared towards being a generic how-to, so it's got settings for rotary engines, but it's also got suggestions for non-rotary engines:

http://www.speakeasy.org/~culverk/wh...oder-howto.txt

Here is a REALLY big pic of a megasquirt (v2.2 board) that's been modded for use on a rotary engine.

http://www.speakeasy.org/~culverk/IMG_0014.JPG

The extra board is a vr sensor conditioner, which conditions the AC sine-wave signal from the CAS into a nice +5v DC square wave that the CPU can work with. Notice the 4.7k pullup resistors from +5v to the negative terminal of each of the led's. These are necessary to provide ignition output to the leading and trailing ignitors.

Also, you can't see it, but to control the BAC valve (and get rid of the thermowax if you want) you can get a ztx688 transistor, and a 1/2 watt, 510 ohm resistor, and replace R16 and q5 (I believe, this is off the top of my head). Keeping the BAC valve is good for things like closed-loop idle speed control... if you want to keep your air conditioning this will be necessary so that when it detects the increased load at idle, it'll bump up the idle speed to compensate. Right now we're using the BAC valve for warm-up idle speed control on tofuball's car.

For the Aux ports and VDI on an s5, you can make a circuit with some transistors to actuate them, and then use a couple of the megasquirt's extra outputs to control them. We are also doing this on tofuball's car.

Also, error* is going to be making some boards that have a lot of this built in, (extra outputs, vr sensor conditioner, EGT logging input, and some other stuff).

 

GReat stuff. Well if/when some of you guys get something that's pretty much plug and play I'd be very interested.

 

Not sure if this is a good idea or not but a nice adaptor harness for the megaspuirt case may be an easier way to go instead of gutting the stock ecu..I guess it all depends on where you would be able to source the stock femal(ECU side) plug.

 

I agree with Ken regarding the full-span TPS. Another application for that TPS it to set up injector staging. Push the throttle open to the point that the secondary plates have started to move off the closed position, and use this position as a transition point (use the TPS calibration tool to fetch the transition value to use). Now you are assured of having airflow in the secondary runners when the secondary injectors come on-line. With rpm-based staging full throttle is fine, but a stumble results if gently accelerating past the transition rpm, as the secondary throttle plates haven't opened yet.

 

People still have the secondary throttle plates? How quaint!

Haha, sorry.. I removed mine a while ago, and I forgot people still used them, and didn't even think of that as a potential problem.. good catch, Renns. A full range TPS would definately be a benifit here..

 

Wonko,

You are misunderstanding my previous post. Let me explain further:

The secondary throttle plates I'm referring to are the two that block the secondary runners at the same position as the primary throttle plate, and anybody with a Mazda throttle body has those! The issue I mentioned is due to the progressive nature of the stock throttle linkage, whereby the primary throttle plate opens part way prior to the secondary plates moving off the closed position. This applies to everyone running a Mazda throttle body with stock linkage.

I realize there is a second set of secondary throttle plates, but removing them does not solve the issue above. If they are left in place, that would complicate things even further, as that second set is closed (over-riding the plates actuated directly by throttle linkag) until the engine is warm. I suppose those that abuse a cold engine will have to live with a little stumble as the secondary injectors come on line.

The full-span TPS also ensures proper operation of closed loop operation in cruise. By default MS uses the TPS signal as one of the inputs to determine if closed-loop mode is allowed. With a narrow range tps like the S4 FC unit, this function is gone, as the tps signal is at its maximum by 1/3 throttle or so.

I'd highly recommend whoever is getting into the MS kit preparation business for rotaries find a suitable full-span TPS and bracket, and include that with the kit. Given the problematic nature of those plunger TPS's, and the rarity of the S5 full-span unit, it'd make sense to adapt a standard rotary type. No use reinventing the wheel here - the Haltech guys worked out this issue years ago.

 

Oh, sorry, you're right.. I was thinking of the secondary secondary throttle plates (thermowax activated ones). I've never noticed a stuttering at my transition point, though, even with my narrow range TPS on my s4. I do have my open loop mode set to MAP, as well as having my injector staging at 3600 RPM.. I haven't noticed it, but I'll try to lightly press the gas and hit that RPM next time I drive the car.

 

The main reason for gutting a factory ECU is because the standard megasquirt case gets crowded with the extra wires and circuitry needed to run a rotary. The stock ECU case is significantly bigger, which helps everything fit more cleanly.