[Gmecm] Back to square one

Sat May 13 19:40:29 UTC 2006

> The main VE tables cover up to 1 BAR.  In 2 BAR mode, higher pressures
> use a fuel multiplier against the 100 kPa entry for the appropriate
> rpm.  Spark tables cover the range from 30 kPa to 200 kPa.  I haven't
> looked through the code to see if flipping the 1 BAR bit forces the
> code to use the 20 to 100 kPa entries, or if it rescales the table for
> 100 kPa max with 2x the resolution.  If it's the latter, then the
> values in the timing tables would be incorrect for the MAP range they
> apply to.

According to PROMgrammer (which I can only assume is correct as it's a well
constructed tool), it is the latter. Not an issue, I know I have to
completely repopulate the SA and VE tables. :-)

> What I can say with certainty is that flipping the bit to 1 BAR and
> connecting to a 1 BAR sensor produced poor idle and driveability in my
> car.  I had no desire to chase the reason, I simply switched to a 2 BAR
> sensor.  I valued the time spent more than the potential for education.

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.

> Wasn't making fun of you on the code modification.  I hope it didn't
> read that way.  That's just the way I talk sometimes.

No offence taken. :-)

> There used to be a turbo Sunbird calibration in the .bin library.   I'm
> not sure where they disappeared to.  Are you using a manual or
> automatic transmission?  If you want to send your mystery sunbird.bin
> calibration I can probably identify it for you.  There are several
> factory calibrations for the 'Birds.

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

> You can load the 4 cylinder calibration directly onto the memcal.
> There's no need to play with the 6 cylinder version.

Thanks.

> 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 ?

> 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/

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?

Thanks,

Robin

> -----Original Message-----
> From: Robin Handley <Robin at FuryWorld.fsnet.co.uk>
> To: gmecm at diy-efi.org
> Sent: Thu, 11 May 2006 10:31:43 +0100
> Subject: Re: [Gmecm] Back to square one
>
>    > $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.
>
> Doesn't %KAFOPT3% bit 5 tell the code whether a 1 or 2 bar MAP sensor is
> connected? Does this not cause everything to be scaled automatically?
>
> > 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.
>
> Agreed. So, could I take the AYBN commented hack for a 6cyl 4.3 Turbo
> Sy/Ty
> and overwrite the lookup values with those from a genuine 4cyl Sunbird
> .BIN?
> Are they a direct map?
>
> > 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.
>
> Agreed.
>
> > 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.
>
> This is where I found my pinout conversion info:
> http://www.thirdgen.org/techboard/diy-prom/213539-58-frequently-asked-que
> sti
> ons.html
>
> Is this the one you meant? I guess it just needs mapping from 730 to 727
> pinout for my ECM. I was just looking for confirmation that I hadn't
> missed
> anything subtle, since the above (and other) discussions just talk
> about $58
> code on a 730 (not a 727).
>
> > 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.
>
> No problems there. I've now looked at the AYBN hack and its associated
> .BIN.
> The hack is 16k and the .BIN has the first 16k padded with $FF - so
> already
> in the right format for my 32k EPROM.
>
> > 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.
>
> The 'not actually a quote from my Email' code modification allows OTF
> map
> changes from a laptop, so I'm pretty keen to be able to reproduce it!
> :-) I
> just wondered if there was a Sunbird specific hack that I've missed -
> that
> might make code changes easier. If not, am I right in thinking that
> AYBN is
> the best/most commented $58 hack to use? The comments with the AYBN
> code are
> a LOT sparser than ANHT :-( although the description of the lookup
> tables
> seems better - and the Sunbird document that I've seen is a massive
> help.
> :-)
>
> BTW: Is the Sunbird code/bin unique? Does it have a 4 letter name, like
> ANHT?
>
> Thanks,
>
> Robin
>
> > -----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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