[Gmecm] Modify $8D to work on MPFI 3.1L DIS engine - It RUNS

[Brendan Patten]

Okay, I did a little work to my $8D bin.

I found this from a 8D Disassembly:

L8025: FCB 17 ; INITIAL SPARK ADV, 6 DEG

L8026: FDB 0119 ; 39 DEG (MAX SA ADDED TO INITIAL)

L8028: FDB FFF5 ; 65525 (MAX SA RETARDED FOR KNOCK) 3.5 DEG


AT 8025 I put in AA 59.8
AT 8026 I put in FFE4  -10
AT 8028 I put in FF39  -70

It started up and ran, now it did throw a cod 51 eprom error, would this
set limp home and bypass my program and rely on the netres?

May try again, not sure checksum was right when I burned.

Its late, I'll play with this more tomorrow, thanks for the feedback, I
think I'll have this figured out soon.

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On
Behalf Of Brendan Patten
Sent: Thursday, August 31, 2006 10:09 PM
To: gmecm at diy-efi.org
Subject: RE: [Gmecm] Modify $8D to work on MPFI 3.1L DIS engine

I actually have already done A1 for support on FREE Scan
 
Mostly I just want to do it to see if I can and to learn the differences
in the ignitions.  I already have TTS Datamaster for $8D, would be nice
to not have to buy another one - say for turbo grand prix would be an
easy route.

Turbo are my eventual plans...if I can get $8D to work, $58 would be
very close.

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On
Behalf Of Jay Vessels
Sent: Thursday, August 31, 2006 9:19 PM
To: gmecm at diy-efi.org
Subject: Re: [Gmecm] Modify $8D to work on MPFI 3.1L DIS engine

Hi there!

Brendan Patten wrote:
> Okay, I want to run the ever popular $8D code on my 1990 Cavalier 3.1L

A quick note -- the $A1 code ('91-'94 3.1V6 VIN T) would be an easier 
choice, and I suspect almost a drop-in.  The biggest changes I can think

of would be to EGR type and VSS type/calibration.  There is support out 
there for that mask, too.  Just trying to save you some work.

> This is what I have found different:
> 
> Initial Spark Advance: 
> F-Body = 9.8 Deg, Cavalier = 59.8 Deg
> 
> Initial Time Out Spark Bias: 
> F-Body = 0.0 Deg, Cavalier = 35.2 Deg

Yup, that sounds about right.  Look to recent posts by Shannen talking 
about what changes between a distributor and a DIS system, but if I 
remember correctly the biggest changes are to the initial spark advance 
and the bounds checks.  Shannen's post was much more thorough.

> If I knew better what Initial Time Out Spark Bias does and how it
> relates with Initial Spark Advance, I could learn how to go into the
> code and find what I need to change.

Your answers may be in the $A1 code.  Search for 727_730_A1.pdf or 
something very similar to that on incoming.  BFUZ is the latest 
$A1/manual trans/Federal code for the '94 Z24 and would probably contain

answers to your DIS parameter questions.

Jay Vessels
1982 Chevrolet S-10 Sport, 2.8V6 TBI
1984 Chevrolet S-10 Blazer Sport, 2.8V6 (TBI pending)

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