Can a GM ecu be set up to run a TII
 

So I'm in the middle of my project here and I've hit a snag. I have a S5 TII motor and trans that I'm putting in my FB I have all the parts to bolt it in except a -SE oilpan, but the big problem is I've almost hit my budget for the next few months and I kind of want to get it going before the snow melts up here.

So I dont know what to do about the fuel system microtech or haltech seem pretty good but out of my price range till my job picks back up this summer.

But I tune alot of gm cars and trucks with HPTuners, and I can get a GM ecu and harness for next to nothing, I can change any setting the ecu controls so maybe I can get a 13b to run with it.

I just don't know how I could set it up right, I could make it batch fire that could make things simpler, but the ignition is what gets me, would I set it up as a 4cyl or a 6? I mean it does fire 6 times per rev right well 12 with the trailing? I don't know. Thats another thing I don't know how I would set it up to fire the trailing plugs a few degree's after. Or I could have the ecu fire the leading and have the trailing fired by a dizzy, but that just sounds like a bad idea that might end with pre-ignition and a dead motor. or I could toss in a 12a dizzy and use the ecu just for fuel, but the I lose detailed spark control and the ability for the ecu to pull timing with boost or high iat's. But at least I could drive it in and out of my shop.

What do you guys think.

Oh yeah a 12a front cover fits on the tII right?

Im interested if this could work..

My brother tunes evos and im so jealous that his stock ecu is so capable and has so many adjustments.....

IF you can get GM ecu to work maybe there is a way to use evo ecus.

It would be nice, I could set up so many fail safe's and it would be obd-II, does anyone how the timing really works on a 2 rotor

I believe the spark settings will give the GM ECU fits, that would be the bigges hurdle to deal with getting the engine to run properly under load and control the timing split.

Thats not really a big deal, but yeah thats the problem I've been dealing with is the timing, I was thinking maybe I could wire it up so coil #1 fires the front and rear leading, and say #3 and #7 to fire the trailing I don't know. I wonder if any of the cyl. are 15* behind say #1 then that could work.

You can have waste spark on the leading, can you have it on the trailing too? or would it missfire or something worse

What has steered you away from the MegaSquirt style computers?

so you know...

A 4 cyl fires every 180 degrees
A 6 cyl fires every 120
A 8 cyl fires every 90

Now a Rotary will fire every 180 degrees like a 4 cyl only thing is it has trailing timing.

I don't see this happening for you.. :)
Only option you have is to use the GM ecu for timing/fuel with no split or use a stock dizzy and GM ecu for fuel only..

+1 Nothing wrong with building your own ECU.

if i was you i would go megasquirt cheap and its prove to work very well on rotaries.

SO he would need to use an ecu made for 4cyl that fires every 180?

evo ecu?
90$ for evo ecu/laptop adapter and free software but it uses afm

but you can get map for another 130$ which is the price of the sensors only.

If it makes you feel better the Megasquirt started out with two guys cracking a GM ECU.

^ To those of you who have knowledge of any of the Syclone/Typhoon ECU's, it's very obvious where the Megasquirt came from. The Megasquirt is a simplified version of the "Turbo PFI System" used on 80s GM SOHC 2.0 engines and the pushrod 4.3 motors used in the trucks.

that's close to how the GSL-SE worked. It had two injectors that were batch fired and it used only an engine speed signal to control them (no TDC signal to tell the ECU which rotor is firing). That's similar to your batch fired GM type of deal. On the SE, the dizzy controlled the spark and the ECU would cut vacuum to it under certain conditions... this is different from the GM HEI ignition of that era, which had a separate ignition module that worked with the GM ECU.

What your suggesting is very crude and IMO pointless, basically a 30 year old approach. And if you used a GM MAF based setup you'd have to install a bunch of GM sensors to make things work and then turn off a gazillion check engine codes. It's just too much hassle, you'd be better off using OEM T2 stuff.

Here's the GSL-SE setup, which is basically what you are proposing except two injectors that flow only enough for an n/a engine:

https://www.rx7club.com/attachment.p...1&d=1265004410
https://www.rx7club.com/attachment.p...1&d=1265004410

On a real T2, you have the crank angle sensor which not only gives the engine speed signal (like a dizzy) but also a TDC signal so that the ECU knows which rotor is firing. The CAS is 24-2 or 24 teeth for the engine speed signal and 2 for the TDC signal, I don't see that working with any GM ECU. That CAS allows for sequential fuel injection, staging, and fully electronic spark advance with a firing order of L1/L2 (wastespark), T1 T2 . A real s5 T2 ECU also has electronic boost control and knock control.

You guys really know your stuff, Thank you for the help.

The thing with megasquirts is they kind of stump me, I also think they are over complicated and some times seem like they are just rigged together, I would use one if I could find a kit with everything I need for a rotary that way I know I have the right things.

I think I could get a gm ecu to work, I can change a v8 to a I4 ecu, change it from 1 bar to 2, 2.5 or 3 with a differant OS, I can make it Maf or SD. disable codes anything.
But I still couldnt run the trailing plugs so thats no good I'm sure the motor would run bad with out them.

run with out trailing i have seen that set up before and works fine

Or run it with no split. Fire both the leading and trailing together..

Yeah I guess I could do that, I read up on it and it should work just fine.

I think the crank reluctor on the LS motors are 60 or 60-2 anyone know what the crank sensor is on the S5.

Or if I went megasquirt and one know what all I need for hardware.

Edit: Anyone know what hardware I'll need

Well on the other hand - the M/S ECU is rather a low class in terms of features and configurable outputs, hardware, etc. Something like a bottom-feeder. Try looking at an ECU like the AEM where most of the outputs are completely configurable to function as injector or ignition outputs,etc etc... its shocking!

Well its a money thing. after adding it up, ballpark to get everything it'll be about $500 to run M/S and about $500 for me to run a GM ecu so I might as well run the megasquirt since it's proven it works just fine.
Anyone know of a idiot proof write up or a website that has good prices.

you can somtimes get a 2nd hand haltech with everything you need even a terminated harness for about 750 +-.


But its always a gamble when your buying electronics

heres a link for the stuff that you need to make the megasquirt to run a rotary hpoe it helps engine.http://www.aaroncake.net/rx-7/megasquirt/

Thank you, as much as I don't like them I think its the best ecu for the money, I heard somewhere that the people who created them built them to teach students about modent fuel injection systems.

so the directions say v3 are they talking about the 3 series (v3 or v3.57) or only the v3, I don't want to buy the wrong one.

The 3 and 3.57 are the same they are small hardware changes that made the assembled kits easier to mass produce.

the v3 its the diyer board and the v3.57 its a surface mount unit but you still have to do the mods for the ecu to work on the rotary engine.hope that helps