I need to go back through and re-read all of this but lets say I have an S4 N/A ecu which means I'm getting 146hp out of my 13b, would I be able to get the maps and such from a S5 ECU and bump my horsepower to 160hp?

Thanks
Grant

 

Pretty sure if you plugged a s5 ecu into a s4 you wouldn't make 160hp, so I would guess no or people would be begging for s5 ecus all the time

 

Ok yeah that makes sense. I'm completely new to rotaries, I went from owning none to owning a 85 gs and a 87 gxl in one week

Still looking forward to this product, data-logging is VERY usefully and doing it through the stock ECU is even better.

Thanks!
Grant

 

I would think a little tweaking of the factory tune would yield a small increase in power over the factory ecu especially since its not a learning cpu.

Im gonna see if I can find a dyno to let me do some testing

 

There's a lot to be gained in the factory maps.... To begin with, they have a very limited RPM range for timing maps. Also, they're insanely rich throughout almost the entire map most of the time.

 

Yeah, you could, although most aftermarket ECU's are using about the same size tables anyway.

 

I was just about to ask this, I just saw in the FAQ stating that these engines were tuned rich, I was wondering if we reduced how rich it runs if we could both gain power and as an added bonus maybe mpg when cruising down the highway as well.

Thanks
Grant

 

I've heard this before, but why would the factory run the maps rich, especially on an NA car? Especially when they want to keep fuel efficiency high, and emissions low? Is there a chance of detonation on an NA if you lean the A/F ratio (i.e. bad fuel, high load, high altitude although we have a sensor for that IIRC)? Just trying to get the full picture.

 

i have put a wideband on several different FC's and so i have data. testing was done on a few different stock cars.

there is also the semantic part where rich is actually a relative term, it is more like richer than. this brings up the second question, richer than what? richer than best power? richer than best economy? or richer than stoichiometric?

anyways, per the wideband the S4 NA idles around 16:1(the air pump air is injected before the O2, so it reads lean), part throttle (1100-3500rpm) cruise is closed loop, so it cycles around 14.7:1, and then WOT goes from 12.2:1 @4000rpm, to about 12.8:1 at 6k, and then over that it richens up, at 7k its about 11.8:1.

the S5 NA idles between 16-18:1, part throttle cruise is closed loop 14.7:1. WOT starts with the same 12.2:1 @4000rpm, but then it linearly gets richer than that, its 11:1 @7000.

so as you can see the two series NA cars run vastly different tunings, the S5 is richer than the S4. there is a bunch of power to be had on the S5 car by simply making it 12.5:1 from 4000rpm up to redline.

however the S4 car is leaner than 12.5 already, so there are no big gains from leaning it out, and in fact you might loose power.

the S4 though responds to timing changes much more than the S5 does however, so both maps need tuning for maximum power, but they need different changes, as they are different

 

very interesting!

That makes sense because of the VDI on the S5.

My thoughts are you could see bigger gains on a streetported car that still retained the stock ECU vs a stock motor with this ECU mod

 

Ok this is going to sound like such a noob question, but is the ideal ratio of air-to-gas in our 13b rotary engine? I'm all for getting the wideband o2 sensor, and also probably getting a good rich/lean sensor as well.

Side question, which company makes gauges that most closely match the stock gauges on the FC?

Thanks
Grant

 

This ECU mod also opens up the possibility of ITB's on a streetported emissions friendly car, which is awesome for us who need to pass emissions testing

I would love to go down that road once the S5 boards are ready

 

^yup!^

 

the long answer is that it depends on rpm and load, and weather we need it to pass smog, or have to make a cat happy long term, etc.

Mazda has a bunch of zones that they put into a Map, pic is from the FD, although the FC has a similar chart.

idle mixture, is just set to best idle quality, no wideband wanted for this, just best idle quality.

the feed back zone, is 14.7:1, which is the mixture the cat is happiest with.

for maximum power, on a non turbo, the mixture is anywhere from 13.2 to 12.5. the S5 is richer than this, but they also needed to warranty the cat for 70,000miles (i think), starting in 89, which means they needed to keep the exhaust temperature down.

a turbo car makes enough power that its capable of detonation, so the mixture needs to be richer than an NA, at full power, its not unusual for a factory turbo car to be in the 10's, and the mitsubishi's are in the 9's.

 

Ran into some bugs that were worthwhile to fix before sending out the last group, but they're all set. The rest of them should all be in the mail in the next couple of days. Focus now is on getting all the feature stuff added into the actual userface in a usable manner rather than my direct terminal junk currently...

 

???

 

To which part?

The bugs were with the firmware updating -- it was possible to fubar the process and get the ECU "stuck" -- so that was kind of important to fix before sending out the rest.

As for the software, right now I do a lot of the testing by sending commands directly to the unit outside of the management software. So, I was adding all of that functionality into the actual software so when the boards arrive people have a way of actually using it for more than just datalogging.

As for the mailing -- most should already be on the way, but I have a couple others to drop off still.

 

Glad it was found before they all got out. Keep at it man, cant wait to start the testing process

 

Great stuff. This whole thread has made me excited haha. I would love to see this ready for use on an S5. Of course, I know that you're not near this stage at this point in time. I'm glad that you're doing all of this though. Keep up the good work!

 

I was curious because you said most were in the mail. What does that mean? I thought you only had 3 as of now? In the mail to you or to us? Just curious if I should be looking for a package or not.

 

Nope, way more than 3. I just have to do them in groups of three, as the boards are sold that way from the fabhouse. There are about 4 local that I had been dealing with first to make sure the ones I actually mail out can be updated without needing a EPROM programmer on-hand.

But yeah, expect a package if you haven't received it already!

 

Cool, I will keep an eye out for one then, might have a weekend solidering project to do

 

crap, I should've read through this thread at the beginning when I had the 7 out, I'm in the tri-city area, my 88 is bone stock, would've been a perfect candidate for testing procedures

If theres other things you may need (I do have a whole engine harness off my other 88, unsure how cut up it is) and other random parts that I saved, ask and I'll see what I got. If your still needing a donor vehicle come spring time for testing, hit me up, may take a drive down to lansing

 

I could use a set of S4 ECU plugs with like 18" of wire left on them -- it'd make testing things a whole lot easier than what I have to deal with now. But, once some people get these things going and I can get real car data, it'll make things go a lot faster as well.

 

Up to you, i'd hate to cut up the harness i have thats still in running condition. But, if you wanna borrow the whole thing and i'll throw my extra ECU at ya too for the mod also