Kenku

Happened across this thread; been looking at it and saw the link from the ECU forum.

I'm building a very high overlap NA car. EFI setup is from scratch anyway, so no worries about harness; it was originally a carbed FB.

How bad of vacuum can the MAP system run well on, and what's the big downside of going to Alpha-N? I know a lot of race cars go Alpha-N so it can't work *that* badly.

renns

Some MS users have successfully used the Speed Density (map-based) config with very aggressive cams. To smooth out the map signal, a small restrictor (mig welding tip) is placed in map line, and a small reservoir (fuel filter) is tee'd into the same line. These two add some 'capacitance' and 'resistance' to the circuit, damping out fluctuations in map signal.

The dual table version of MS code also allows for the blending of speed density and alpha-n, so you get the 'best of both worlds' so to speak. This is the scheme used by Ferrari on the F40. See notes here for more details, including drawbacks of the pure alpha-n systems:
http://not2fast.wryday.com/efi/blendingMAPnTPS.shtml

Kenku

Ahh, thank you. Forgot about that one. Hmmm. So looks like that might work... not sure *exactly* how I'll get the thing started initially (peripheral port, and I'm planning on the worst) but that's just fiddling with start values. Really would prefer to get it running in *SOME* form before going off and mucking about in the code though.

Bah, if I didn't want to experiment I'd not be homebrewing a pport motor.

Liquid Anarchy

iTrader: (2)

razorback

anarchy is that yours? where did you get it? how much did it cost? when im home im like 45 mins away from you. how much do you know about these units?

arch8300

is that a pic of it completed or unsodered??

DCRotor

iTrader: (2)

Arch8300
it looks complete to me ( ie. all the components on the board)

razorback
if you want on you'll hav to build one or buy one from ebay or yahoo go to http://www.bgsoflex.com/megasquirt.html it will let you know all u need about building/buy it

drago86

Ummm look at the picture? does it look like a bare PCB?or one with crap on it?


Question: What exactly does the dual table map do? Everyone with a rotary seems to run it. Is i the SD and alpha-n stuff you were talking about? also can the MS be set up sequentially like the stock injectors?

renns

MS has two injector drivers. Using the standard code version, these injectors are either driven simultaneously, or alternating. This doesn't suit the stock Mazda setup, as we want to fire primaries only during idle/low speed operation, as the progressive throttle body has the secondary runners closed off during this mode of operation.

The dual table version of MS code allows completely independent control of the two injector banks. Others have used this code to run fuel on one injector bank, and either water or NOS on the second bank. In our application, running fuel on both allows for indepenent tuning of primaries and secondaries. This can be set up to emulate the stock injector staging scheme if so desired.

The dual table code also has some other goodies built in: boost controller, BAC-compatible closed loop idle control, shift light outputs, secondary rev limiter for launch control... Most of these functions need a daughterboard with appropriate interface hardware to drive them, but the documentation is there to put it together if you are in to that sort of thing.

Liquid Anarchy

iTrader: (2)

That is a ~96% completed MS. I lost one of my mica packets, so I still don't have 2 of the components on; also the LED's still arn't soldered on.

Hooked it up to th esimboard... plunty of blinky lights.

I really don't have too much done with it, I intend to do the same as Twisted Rotors' friend. Built 13B N/A w/ a 12A distributor... but mine is a 9.7:1 4-port.

As for my education on the MS, it's limited... but there will be a couple cars locally running them, upon completion of a few projects in SPRX-7. I just hope I don't blow somethign up tuning it.

Mx6-Rx7 Addict

Ah yes, finally a few more MS controlled fc's on the forum..

My car will be running the megasquirt hopefully in a few weeks, when i get around to it.. But i really want to run Tweakit's IDA throttle body setup... its been bugging me every time i see it. I will also be running the 12a distributor. It really will clean up the engine bay without a stock manifold and no engine harness.

The megasquirt seems farely easy to tune.. we got the car to idle right away when we first installed it on Twisted Rotor's TII. We had a problem at first though, we had the dual table code setup so that all four injectors were putting out on idle..(a lot of smoke, and a stockport 13b that sounded like a bridgeport).. Once we figured out how to turn off the secondary bank, we got the car to idle somewhat good... We began tuning the primarys.

Beware, both myself and twistedrotors will recommend to buy a decent wideband system, or make sure the wideband DIY is properly working.. Learn from our mistake. A wideband system is almost necessary to properly tune the unit.

Justin

Madrx7racer

http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW ........I might look into one IF i ever get my damn car started.

locketine

guys, soldering isn't that hard. it took me a few hours to learn to do it perfectly and in a timely matter.

razorback

there is a guy that sells them for like 230 assembled. just search google for megasquirt units for sale or something like that.

RETed

Please, the term "stand-alone" implies control of both fuel and ignition.
Reading through the replies, it does not control FC3S ignition systems or have I seen someone figure out a way to do this.

You gotta be kidding me you're going to compete with the Haltech (E-series) or Microtech (LT-series) stand-alone ECU's, cause at least both of them have very capable ignition timing control capabilities utilizing the stock FC3S ignition components.

Right now, it's a DIY fuel computer that's really only comparable to the Haltech F-series fuel computers (Haltech doesn't call their F-series computers "stand-alones" either.) or the GReddy eManage unit.

I'm not rapping on the MS units (they do have their niche), but I object to the loose use of the term "stand-alone", which is clearly isn't at this point in time.


-Ted

razorback

actually i did read that they can control ignition too. i cant remember where i read that i will try and find it tomorrow...err..today

RETed

I believe the mention of "distributor" ignition timing control was mentioned.

Typically, this means a single channel if ignition timing control which is next to impossible to implement on the 13B.

The stock FC3S ignition timing control uses a two channel ignition input (home and sync) and a three channel ignition output (leading signal, trailing signal, trailing toggle).  Stand-alone EMS units like Haltech, Microtech, MoTeC, and Wolf have no problem mimicing this design and able to use the stock ignition input and trigger the stock ignition outputs.


-Ted

renns

The term 'Stand-alone fuel controller' is well suited IMO, as it differentiates the product from the S-AFC and other similar products that do not control the injectors directly, but just fudge one or more sensor inputs to the stock ecu.

True, there is no complete rotary ignition solution. If a complete solution is desired, and it is in the majority of cases, then a commercial product needs to be pursued.

Very true. The MS is comparable only to other fuel-only controllers when considering rotary applications. As mentioned in a previous post, there are ignition solutions for Ford EDIS, TFI and distributor-based ignition systems, so in those applications the full 'standalone' term is warranted.

No harm or deception intended with the 'standalone' term, but I still feel its valid if qualified properly (fuel only). Otherwise, there is no way to differentiate between the s-afc type gadgets and a full efi computer.

I'd guess 99% of the MS units are built, tested, installed, and tuned by the builder. This approach is not for everyone. In fact, most people (especially those with high-$$ turbo rotaries) should simply pay the $$ for a commercial unit and have it tuned by a professional. Why risk a $6000 engine with a $200 computer tuned by a first-timer?

Travis R

I've been interested in the MS for a couple years now. I know I could build it, and I think I could tune it with a WB. but I'm scared of all the "source code" talk. I'm no programmer. Will that knowledge be necessary to make it work, or only if I want to monkey around and do custom stuff?
I've mainly been waiting for ign control too.

jkrueger

iTrader: (2)

I'm in the middle of tuning my 87 TII with a Megasquirt that is using the dual table code. I just want to say to the people that are worried about being able to build one or about programming, that it is very easy to build and no programing is nesscary.

I had never soldered anything before starting this project. I bought a DIY electronics kit to have some practice with soldering and then I built the MS simulator and then the controller itself. It was not hard at all. There is an excellent manual avaible that Lance has put together available on the website. It covers everything from the theory of the MS to building it to tuning and turbo applications. I would highly advise anyone interested in building one of these to look through it. Here is a link.

http://members.shaw.ca/megasquirt/manual/mtabcon.htm

The rotary application is a little different than the piston one, but there is great support on the yahoo group from other RX-7 users and Eric has developed the dual table code that works very well on the rotary. I don't know squat about programing or programing chips and it was very easy to load the software on the chip.

Having the stock ECU run the ignition is no problem. All you have to do is hook the MS up to the injectors and a coolant and air temp sensor. As renns mentioned, some people are using distributors in place of the CAS. I plan doing that as well as soon as I can find a 12a turbo distrubtor.

The tuning has been going well. The car started right up the first time running the MS. In about 10 minutes I had idleing well. Three laps around the block and I had running pretty well in the low rpm and map range. I'm going to a dyno next week to tune the upper rpm and boost range.

It is a great project for someone that wants to learn more about how a EFI system works and how it applies to their car.

patman

iTrader: (3)

So the stock ECU runs the ignition fine even with the injectors, AFM, Temp sensors, TPS, etc unhooked?

pat

jkrueger

iTrader: (2)

I left the tps hooked up to the stock ecu and added a second one for the MS to use. I wasn't sure if the stock ECU used that signal for any boost retard. But as far as the AFM, injectors and temp sensor. It works fine without them.

JC

TwistedRotors

iTrader: (3)

Hey, just ran across this thread and thought I should throw in my .02.
Just like Mx6-Rx7 Addict said we got my car ('87 Turbo II) running very easily with the MS. I was running the Dual Table Code (more info on the MS FAQ site) with lot's of help from Renns. We had the primary injector map tuned pretty close to perfect. I could hit about 6.5#'s of boost and go up to 4k rpm before the primaries started hitting around the 80%+ duty cycle. Then I decided to try tuning the secondary map and it all went down hill. We got about 2 good pulls all the way up to 7k and the car felt amazing but on the third pull at about 6k the motor let go. I was using a DIY wideband plugged into the MS and Mx6-Rx7 Addict was watching the display on the MS tuning software the whole time and the mixture never went lean. I'd like to say that I killed my WBO2 sensor by not letting it warm up enough prior to starting the car, but like Mx6-Rx7 Addict said we will be going with a professional wideband (probably the Innovate unit) next time.
I think the MS is a great unit and I know that it was not what caused me to pop my motor. That would be my in-experience and possibly my wideband. I would have liked to stay with the MS, but I just don't like having to have to ECU's.....if my car was NA then I would definately go with a 12a dizzy and the MS. Until the UMS comes out (end of the summer?) then I am going to run with the stock ecu or go with a Microtech.
Final words: MS is not for the faint of heart, if you decide to build your own then do yourself the favor and get the stimulator. It will save you hours of headaches later. The soldering isn't hard, just go slow and follow the guide and you'll be just fine.

-John
www.TwistedRotors.com

jkrueger

iTrader: (2)

Hey John, How goes the rebuild?? I've got the lower part of my ve table pretty set. It actually drives like a "normal" car now. I was pretty lean in a couple of places and my accel enrichment was off a bit. I'm taking it to a dyno tomorrow to work on the upper areas of the ve table. I'll let you know how it goes.

JC

TwistedRotors

iTrader: (3)

Hey JC, glad to hear everything is going good with your install and I'm really glad to hear that you are taking it to a Dyno. Lemme see some numbers when you get it done!! I also was having a little trouble with the Accell Enrichment, just gotta play with the numbers until it starts feeling right. If you need some place to host your dyno sheet just let me know.
My rebuild goes slow. Lot's of personal life stuff going on, plus work....leaves little time for the car. I don't want to clog up this thread with non-MS related posts so if you want, you can find more info on my rebuild on the site (www.TwistedRotors.com).
A few more MS notes: I would agree with Renns in that it should be called a stand alone FUEL controller. Modifications can and have been done by others to make it control ignition (MS-n-EDIS, MS-n-Spark etc. etc.) but none of those will work right for a rotary.
And as with any stand alone (fuel or otherwise) you should do your tuning on a dyno. It can and has been done on the street successfully but this ain't no SAFC....you can seriously mess up your car if you don't know what you're doing. Like me. :-P

-John
www.TwistedRotors.com