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

[Jay Vessels]

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)