A huge thanks goes to JustJeff for sending me his OMP fried n370 ecu!!!

I got the ECU today and pulled the Eprom out, and tossed it on my burner/reader
I compared the Differances between the stock n374 and the n370, theres 30,973 differances out of 32,000 (my toms tuned n374 mapped to 15psi has more in common with the n370 its 30,953), the n374 has different fuel an timing maps....the knight sport chip with its modified fuel and timing and fuel and boost cut removed only has 850 something differances from the n374
it'll take me probably the weekend to brake it down more to see how much of a change

I'll post more when i figure more out.....I was just surprised, everyone would always say the only differance was in the emmisions but they are 2 totally different tunes, I just think noone has had a working stock n374 to do the actual do a comparison too, someone with a RHD would probably never put a n370 in there car

i'll sell someone a chip dirt cheap to dyno there car with thier n370 and then toss in the stock n374 to compare

 

i've been goin over them a bit...it definately has different fuel and timing

 

It seems as though you have a collection of several different Firmware chips from either N374 or N370 ECUs. I am curious as to how you are inspecting and comparing the device contents.

Are you just inspecting the Binary (hex) files for differences or are you disassemblying and looking at the program instructions?

If it is the binary file comparison, how do you know where or what anything is?

I'm amazed and baffled?

 

HEY!! congrats on the success so far. I was just going to toss you a PM and see if my ECU had been helpful. Very interesting find so far. I'll be watching the threads for your progress. Good luck with it.

Also, toss me a PM. I want to learn more about EPROMs and would love to find some good resources. In all honesty before I sent you my ECU I knew nothing about them other than it's a means to burn custom coded chips. I was simply trying to be helpful to a fellow rotorhead, but now my interest has been sparked.

 

just thinking about emissions, odds are the timing and fuel maps are going to be different.

 

How's things looking?

 

I wish I understood a single word your saying lol. I have a chipped n374. Im really curious as too what its chipped for because it came w/ my engine. Do you know a way to tell because I would be half tempted to send you it just to find out.

 

double post do to internet freeze...

 

I've have a "process" lol, I have a VERY crappy binary disassembler, TunerPro RT (has a differance tool and hex editor, and I can look at the maps in 2D and 3D)

i've been toyin around with altering my mx3 ecu map It's more forgiving if something isn't right
And lots of time lol

I need to find a better binary disassembler, or reverse engineering program then i can havin the confidence to alter fuel and timing maps

I found definitions for my mx3 ecu, and can modify the fuel,timing,VRIS points,
If i could find something like that for the n37X ecu's that would be great too, I gotta get ahold of the guy that wrote the definitions for the mx3 ecu, see if he could assist me with writing some.....he has a killer disassembler but its a licensed version he paid for.....and i'm to cheap

 

Could you maybe post up the N374 original dump? That would be awesome =)

 

Just an fyi, this thread is 13+ years old, though the OP was last online 4~ ish months ago, so maybe a PM might work out.

 

I'm just as curious with the N370 rom. I was gonna buy a rom programmer to rip mine, but if he's got ahold of it, then it doesn't hurt to ask. The video game enthusiasts have been doing a lot of restorations with rom based devices, and I think it would be to our benefit to decipher these things. SonicRat has done a bunch in another thread. Might be good to circle the wagons on this.

 

I agree completely, I just wanted to reiterate with my previous post how old this thread was. It would be nice if someone could analyze the rom dump between the two and figure out exactly why a N374 will not fire the rear rotor injectors in a NA -> Turbo swapped car, yet they will run a factory TII car just fine.

 

ive allready solved this,
the JDM ecus have a speed limiter which fuel cuts the rear rotor.
When T2 swaping a USDM NA vehicle and using the JDM ecu, one of the NA car wires which is different from the turbo models pinout ends up triggering this, If you simply cut that wire at the ecu, the car runs completely normal. ( ive forgotten which wire it is, but i researched this several years ago and got a car working with it)

 

I remember talking to you back in the Aim days. Do you think you might be able to point me in the right direction to find that pinout? I have a second FC that I can't find a N370 ECU for to save my life.

 

Has been done I think: https://www.rx7club.com/2nd-generati...8/#post8009976

I have also a S5 US Spec convertible that is NA to turbo swapped with a N380 ecu and works fine. The only thing that need extra wiring is the boost gage and the cruise control

I have 3-4 N380 ecus here (EU-Spec S5 TII), if you want I can sell you one. It has no speed limited from the factory. I also found out you can use a N374 rom in the N380 ecu without issues (I am using one now with a redom re amemiya N374 dump as it runs just fine)

 

I believe it is pin 1U on the ECU.

Old post from years ago. Looks like it's since been found to be correct.

New thought on N374 in TII swap problem - RX7Club.com - Mazda RX7 Forum

 

My issue is, the car was originally an auto. I've since five speed swapped it, obviously, But I'm wondering how that would play into things with those pinouts? It's still using the auto harness. Runs fine on the auto N/A ECU, but I don't feel comfortable boosting it for obvious reasons.

By that guides logic, since the car is originally auto, it should be seeing 0v instead of 12v, as the car isn't a factory five speed car, so there's nothing there on it to send that 12v current to that pin. I think I'll back probe pin 1U at the ECU with the ignition switch to 'ON' and see if I have 0v or 12v.

Its been a few years since I swapped the car, but I want to say it didn't idle right with the N374 or the N370 I put in it (the N370 was bad, tried to reman it, and the company said the idle circuitry was bad, but they didn't want to mess with it..great company.) I put in another N370 (or so I was told, could have been a bait and switch) from an ebay auction that was "working" but the omp circuitry was fried and it was in limp mode, idled okay though.

I can't remember 100% if it idled on the N374 ECU, or if I just automatically assumed it wouldn't fire the rear rotor and didn't even attempt to use it. I want to say I would have been more thorough, though. Only one way to tell, I need to source an N374 ECU.

 

there is another thread somewhere, where we did actually figure out that the 1U is the speed limiter pin, so if you put an N374 in a US car every so many miles it will run on 1 rotor, because of the mileage switch

solution is just to remove the pin from the connector, no speed limiter, no mileage switch, no problems

 

lol we talked about this in a thread several years ago as well, i had cut pin 1M which was the mileage switch to make the one i was working on run correctly.