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

[Ryan Hess]

The obvious question to ask, is why?  Seems like a lot of work for nothing to gain...  Are you trying to find more tuning support or something?  I'd suggest asking your questions at 60degreev6.com if so...

To answer some of your questions, there are values in there that you need to change that you do not have.  Or maybe you called them different things, I'm not entirely sure.  The spark reference angle will need to be changed.  This is basically a reference to where TDC is compared to your reference signal.  The min/max spark advance are features your DIS brick set.  I think there's some others, but I forget.  It would be best to copy the fueling and timing tables over...

Ryan

Brendan Patten <bpatten at centurytel.net> wrote: Okay, I want to run the ever popular $8D code on my 1990 Cavalier 3.1L
I have been looking at the stock files for each and this is what I have
found

I am going from $88 code ATMF to $8D AUJP

I think my main problem areas are the ignition control.


The First thing I have done, is compared a $88 Cavalier to a $88 Camaro,
both are 3.1L MPFI, but Camaro uses a distributor, cavalier is DIS
ignition.

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

Main Spark Advance Vs. MAP Vs. RPM

The F-Body has up to 20 degrees more timing in 40kpa 1400 to 1800 rpm,
and an average 12 degrees more timing from 20-55 kpa, 800 to 2800 rpm
80+ KPA areas are within 4 degrees on both vehicles.  Is there a reason
the spark is not cranked up more on the DIS engines?  Or is added some
other way on another table?

Now the questions I have about going to $8D

$8D has a constant: Maximum Spark Advance. - AUJP stock is 41.8 Deg, how
does this value effect if I put Initial Spark Advance at 59.8 Deg?????
There is no MAX SPARK ADVANCE on the $88 to compare it to.

$8D does not have Initial Time Out Spark Bias, this seems to be
something major different between the two $88 vehicles, but no setting
to change on $8D

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.

Anyone know much about the DIS ignition control compared to distributor?


Thanks...

Brendan
www.lt1swap.com



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