[Gmecm] Back to square one

[davesnothereman at netscape.net]

-----Original Message-----
From: Robin Handley <Robin at FuryWorld.fsnet.co.uk>
To: gmecm at diy-efi.org
Sent: Sat, 13 May 2006 20:40:29 +0100
Subject: Re: [Gmecm] Back to square one


"I'm in a different boat. I am applying GMECM hardware and software to 
an
engine that never used it - so I know I've got mapping to do - but the
saving grace is that I intend to keep things simple. Many 'tweak' arrays
will get set to zero to make life bearable. After all, the GMECM has 
about
10x the number of adjustments that an aftermarket ECM provides (e.g.
MegaSquirt, Emerald M3D) and plenty of people are blatting around with 
those
running their engine's fuel and sparks."

You're right, of course.  There is a relatively large margin in the 
conditions that will allow an engine to run.  When the sophistication 
of the driver is not so high, or the conditions under which the engine 
is expected to run at its best are significantly narrowed, it's fairly 
easy to obtain acceptable results with even primitive systems.

I should probably know this... you've been around for a while.  What 
engine are you working on?  Is this a Ford engine?  Vauxhall?


"Happy to send you the .BIN (in fact I have ended up with 2 over the 
years -
that have come from different sources, but they appear identical). I'm
curious what, in the .BIN, tells you which calibration is. Is the 
following
enough:?

PROMID = $0D53
DATECODE = $0D2A
SEQNUMB = $058C
KKPGMID = $58"

The promid will usually work, but I can compare the checksum to the 
values in the calibration and sometimes come up with a proper ID.  
Promid 3411 is AUWR3607, 1987 Sunbird GT 2.0 Turbo, manual trans.


> Yes, the information you linked to on Thirdgen.org looks like what I
> was thinking of.  Ludis Langens made a nice equivalency chart for 7727
> <-> 7730 pin functions.  Sorry, I don't have a direct link.  I just 
use
> Google.

This one: http://www.cruzers.com/~ludis/triplugecm.html ?

Yes.

> The AYBN hac which is floating around was likely authored by the same
> person who wrote the 8D hack.  It's not complete, nor is it completely
> accurate.  But it is a decent starting point.  It's acceptable for use
> with the Sunbird code, although certain minor functions differ between
> the two applications.

I've spent all day going through a document that was brought to my 
attention
recently by another helpful lister, which was called Sunbird.doc. It 
seems
to be a differently formatted version of this:
http://www.sunflower.com/~leroy/P4/

Ahh, yes.  The turbo P4 paper.  It's been the starting point for years. 
:)

I've been matching the calibration variables in that document with a 
text
export of my Sunbird .BIN from PROMgrammer. There is a massive amount of
agreement, but a few differences - which I wasn't expecting if the 
document
and the .BIN are Sunbird. I'd love to understand how that document fits 
in
with Sunbird and Sy/Ty $58 code. Can you help?

Possibly.  I would guess that the P4 document was written by someone 
close to, but directly involved with, the GM $58 code.  Some of the 
functions are described incorrectly, some of the described functions do 
not exist in the $58 calibration, and some of the important functions 
are missing altogether.  The GMECM world has been a detective's 
paradise for years.  And the turbo P4 document is akin to clues based 
on hearsay.  I may not have knowledge of specific issues in that 
document, but I'll try to help with any you've found.

Zaphod
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