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Discussion Starter #4
Jesse knows more about this stuff than I do. A word of caution: you likely will need a B63 code ECU from Japan unless you want to crack the B61 program yourself to find out the hex addresses for the fuel and timing tables.

http://forum.miata.net/vb/showpost.php?p=467693&postcount=12

jesselee said:
The Miata factory computer of all years IS REPROGRAMMABLE. However, to do so you must desolder the original ROM and plug in your replacement ROM via a custom made adapter baseplate. The hardware and software to do so are available from Grid in Japan and have been for a while.
http://forum.miata.net/vb/showpost.php?p=467698&postcount=17
jesselee said:
As far as I understand (from squinting at the horribly translated japanese for hours) the stock ROM is still plugged back onto the add-on baseboard. The 1.6 NA6CE integrates both the 'logic and control' portion and the 'data' portion into the same ROM chip. What the Grid baseboard does is separate out the 'data' portion and farm it out to a reprogrammable blank PROM, but retains the 'logic and control' portion of the stock ROM. Grid also sells software to allow you to read the stock map and modify it whereever you wish, including the rev-limiter if you buy their 'environmental file' package.

So yes, you have to break out the soldering iron, but you are essentially reading and reprogramming the stock ECU. This is NOT the same as plugging in an aftermarket ECU where you toss out the factory tuning and input/outputs entirely and start from the ground up.
http://forum.miata.net/vb/showpost.php?p=102417&postcount=15
jesselee said:
For the 90-93 Miata, apparently the 'data' portion and the 'logic' portion are integrated into the same chip. In order to separate them you'll need to purchase an "add-on baseboard" from Grid of Japan.

For the 94-95 Miata, my understanding is there is no add-on baseboard necessary, you just unsolder the ROM chip, copy it over to your own EEPROM chip, and start altering away.

It seems like you would need a EEPROM eraser, EEPROM programmer, and a knowledge of the address locations of the fuel and ignition maps, which are given in the links in my first post. And luck, lots of it Oh yeah, if you're getting real fancy, a EEPROM emulator would let you play w/ the numbers to your heart's content, and then once you're happy w/ the numbers, go ahead and burn them into your EEPROM.

BTW, all this information is gleaned from the very poor altavista translator... so don't take it as gospel yet
 

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Discussion Starter #5
Technosquare is a US based alternative to Grid.

http://forum.miata.net/vb/showpost.php?p=1549398&postcount=3
jesselee said:
Technosquare can sell you a Techtom latch-IC board for $320. They will also dump the stock factory program into your 27c256 flash rom chip for ~$80. From there on, you're on your own as far as cracking the USDM B61 program.

They can also sell you a already modified program for $685- I'm guessing that one is a JDM B63 program, which is already cracked, and the bits for the air fuel, ignition and redline tables are already known.
 

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Wow... so this stuff is in existance. (new to miatas)

We've had this format of ECU modding with Honda Ecus for a number of years now. I use a few of the DIY systems that allow you control of everything in the stock ecu through a single chip replacement....

Looks like I found my route for the new Miata.... If I have any breakthroughs (doubtful... but ima try) I'll post them up.

We need more electronic guys I'd suspect... I know their is a core group that has helped do it for the Honda guys... www.pgmfi.org. I'll see if I can elicit their help.
 

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I've thought about this thing long and hard.... the basic difference bewteen the Honda ECU and the Miata ECU is that the Honda ECU is MAP based, and inherently much more friendly to mods.

The Miata's ECU has 2 limitation:

1. Biggest limitation is the AFM. It just plains sucks. 1.8 w/ the MAF is much better.

2. 8bit! the 256 levels don't go very far. It's barely adequate for NA I guess. But for forced induction it really is inadequate. I understand the OBD2+ ECU's are 16 (or more?) bits. But of course you can't reprogram those.

If you have a 94-95, and you intend on staying NA..... then I suppose it's worth a try. On the 1.6's I would skip the experiment.
 

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Agreed, the Honda ecu is great for what it is. And being able to run bigger map sensors and adjust the program maps accordingly is awesome.

So its kind of a loosing battle to follow this path eh.... that really bums me out.

I guess i'll go MS or something then. I can convert to MAP and all kinds of stuff then can't I?

Sigh... still so clueless with miatas... maybe thats because I've been researching and such for just a few days since I bought one :p
 
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