Re: 7749 guru needed....

["Green" <green@dsl.telocity.com>]

> Green wrote:
>
> > Changed that as well;  there's a calc that computes the fake 1 bar and
> > checks for overflow. Basically had to get new constants in that calc to
take
> > ~ 1/3 of full range for vac, rather than ~1/2 from the 2 bar.  I believe
> > this is the only part of that code section that needs changing ?
>
> No.  The MAP in kPa calc should be changed also.  Last I looked, the
> 3 bar MAPindex had not beeen re-scaled.  Some of this is just how
> "correct" you want to be in your calculations.  It can be made to work
> with fewer changes.

I realize what you mean now.  How accurate do i want the values vs. the
table column lookups to be.  I'm going thru that calc now so i understand it
fully....  saw the 1 bar "fake" MAP index calc in that area also.

>
>
> > So the big code change i made was the 3 bar to vacuum calc.  The changes
in
> > the tables portion of the chip are extensive also.
>
> Most of this should have been minimal, except the main spark table.

Extensive is a relative term i suppose :-)  Variables and such need to be
scaled if they use full range raw map value for comparison etc.


> > The 2 tables (open throttle and closed)  now have a bit less resolution;
not a
> > big deal at idle, but at open throttle, you only have like 2-3 lines of
table
> > in vacuum, for drivability tuning.
>
> A wrong assumption here somewhere.

Ah yes i found that.  Disappointed in myself that i let that go so long ..
geeez...  after all the time i've spent on this chip.

>
> > So i'm hoping to change the way the VE tables are setup now.  Maybe make
one
> > for drivability, that uses vacuum, then make the other in use during PE
mode
> > only, using full range ..? I'm not sure yet.
>
> You already have the 20 to 100 kPa tables now.  You could add a two axis
> table for VE changes above baropress.  These values may be harder to
> determine
> though!

hmmm  could try and find space for a table similar to the F77 boost
multiplier table, use those values as a start, then tune as needed.

I'm just trying to find a bit easier tuning for higher RPM/high boost
fueling, as my truck (and others) are revving in the 5000-6000 zone, and the
high RPM fueling is not really easy to tune as it would be if I were using a
2 axis VE table with good resolution.

thanks Scot

Brian Green


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