[Gmecm] Back to square one

Wed May 10 19:22:38 UTC 2006

Hi.

$58 for the 7749 will work in an NA application.  It's going to expect the 2 BAR MAP sensor.  To use the 1 BAR sensor you'll need to re-scale some of the tables.

The turbo Sunbird was the first to use the $58 code.  The Syclone and Typhoon were second.  It's better to start with a calibration for a 4 cylinder car.

The $58 calibration does not have tables which extend to 7000 rpm, although it does provide a means to adjust fuel and spark after rpm exceeds the maximum tables entries.  It probably won't be an issue.  At that engine speed you're not usually looking for high resolution tuning.

Other people have used the 7749 calibration in a 7727 / 7730.  I believe there's a page on the thirdgen.org site which details the correct pinout, but I might be wrong.

The turbo Sunbird calibration is 16k large.  It will fit on a 32k eprom and work.  You will need to move it to the "top" of the chip.  Look for instructions on "bin stacking" for one method to do this.  The memcal must match the calibration in the number of cylinders it's designed for or else there will be a "cylinder select" error set. 

To make the "special secret super duper code modification" you'll probably need to learn the $58 code.  There may not be an equivalent function in the $58 as you worked with in the $8D.  

HTH
Zaphod

-----Original Message-----
From: Robin Handley <Robin at FuryWorld.fsnet.co.uk>
To: gmecm at diy-efi.org
Sent: Wed, 10 May 2006 10:04:42 +0100
Subject: [Gmecm] Back to square one

After a couple of years of researching and playing with GMECM, I thought I
was getting my head around it but, having started thinking about changing
the code in my 16149396 (1227727 with SRAM) from $8D/ANHT to something
possibly better hacked and easier for me to understand all the arrays/tables
required in applying it to a 2 litre 4 cylinder naturally aspirated engine
that will rev to 7000+RPM, I am now confused and need help/advice.

I've read quite a lot recently about Turbo Sunbird code and it being
identical to Sy/Ty code. What I've read tells me that both originally ran on
1227749 hardware, that they are part of the $58 family, and that the EPROM
size fitted to this hardware was 16k, whereas 1227727 & 1227730 hardware
came with 32k EPROMs fitted (what I have). Also, that it is possible to run
$58 code on a 1227730/1227727 if a few ECM pins are wired differently. I
don't have or want IAC or EGR or any transmission connections, so I think
the only one that might matter here is the wire to connect to my injectors.
Have I got the above correct? :-)

So, if I am to do the switch from $8D/ANHT to $58/Sunbird code, and get back
up to where I am now, I need a .BIN (I have something called Sunbird.bin,
but no idea what 4 letter designation this relates to) and I need a
commented hack - for ALDL monitoring, reference, and code modification (I've
done a nifty change to ANHT that I really need to recreate with any new
code). A .ECU would be nice, but I am capable and happy to generate one from
the hack.

I've looked at the .BINs and hacks on www.moates.net (which seems to be a
copy of the www.diy-efi.org equivalent, but with hacks) and found 4 1227749
$58 4.3 Turbo .BINs (1576BBZA58, 1618BBZB58, 4175AYBN58, BBZB1580 - all 16k)
and one $58 hack (AYBN - which is configured for 6cyl but mentions Turbo
Sunbird in the header, and the accompanying .BIN is 32k !!! - This confused
me, can anyone explain?)

Could somebody with a good overview of GMECM put me straight, please. :-) Is
the Turbo Sunbird code the best start point for a 2.0 4cyl NA engine? Is it
the exact same code as the 6cyl 4.3 Turbos, but with different lookup
values? Will Sunbird code run on 16149396/1227727 hardware (I'm in the UK,
so getting new ECM hardware is not trivial) with a dizzy reluctor trigger
feeding an 8 pin GM HEI? (I don't have/want EGR, IAC, or any transmission
related stuff - just something that will run my NA engine's ignition and
injection - after tuning (obviously) - but with clear visibility about what
needs to be set, and what it actually does.) BTW: I have a WBO2 for tuning,
and a MAP sensor with the following ID: 460 7236 (which I believe to be a 1
bar sensor, but this number does not match that on a web site of GM
sensors!)

If so, please advise which .BIN should I start with, and which hack? And can
I reuse my MAP sensor (I believe the $58 code has an option for a 1 bar
sensor)?

Help! (Sorry for all the questions.)

Robin

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