ECM 1227748, creating a new ECU file?

[steve ravet]

Nick, I have the same ECM and am hoping to put it on a boat some day.  I
have looked through a few bin files and there are 7 or 8 or so 3d tables
that jump right out at you.  That's the extent of my work, though, I
don't know what the tables do.  Tunercat doesn't seem to support 1227748
although he might be talked into it.  I doubt Terry K has an editor
either, just because it's not that common an ECM.  but who knows, as
him.  I'd be interested in swapping info on this ECM if you come up with
anything.

Nick McAlpin wrote:
> 
> What does it take to make a new ECU file from scratch?
> 
> I'm the one with an 88 coupe who got some help from the list over
> the past few days (thanks all!) and i am interested in working with
> the EPROM code/tables a little bit but being a less common ECM,
> the ECU doesn't seem to exist.
> 
> So, my question, is building an ECU really not much more than
> looking through the bits of the .BIN, identifying tables purely by
> pattern and then playing with them to find out what they do?  what
> about single byte memory spots - do you guys just change the
> value one byte at a time to find out what it does?

Basically.  Once you find the tables, you can start changing values
(like zero out an entire line) and see what the effect is on timing or
fuel.  You don't want to do that on a car, you want to do it on an ECM
testbench.  There is some information about building an ECM testbench on
the WWW page http://diy-efi.org/gmecm/projects/ecm_testbench/

There is some info in the archives, mostly from Ludis, about this ECM. 
Search around in there also.

> 
> is there any standardization in the table formats of ECM's?  For ex.
> if I find a table of size X columns and Y rows that it is probably
> table Z?  or is every ECM/bin different.

As I understand it, bins that share the same mask code have tables in
the same places, and the same sizes, as each other.

> 
> It seems like if I have to start from total scratch, I could end up
> burning 1000's of EPROMS and doing a lot of guesswork (and hope
> not to break anything in the meantime?)

Yes to the 1000's (unless you get an emulator), no to the breaking stuff
if you use an ecm testbench.

--steve

-- 
Steve Ravet
steve.ravet at arm.com
ARM,Inc.
www.arm.com
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