Re: 7749 question

["Jim Sloan" <leroy@sunflower.com>]

> In the SyTy 7749 ECU fuel control scheme, where does the Injector Flow
Rate
> enter into the BWP calculation equation?  There's no mention in the P4
> document of this term; there's the BPC term, which supposedly compensates
> for engine displacement & injector flow rate (& EGR).

I'm not sure what the injector flow rate is used for.  I'll edit that
sometime when I have my emulator hooked up and see if the a/f ratio is
affected.

> Reason I ask is that I'll be changing to some 40#/hr injectors from the
> stock 29#/hr flowrate and I'm wondering where to input this new info for
> the ECU to "see".

Sounds like an opportunity to finally get some good data for a 40# chip.
>
> Promgrammer has data fields for both terms, one a Gal/Hr injector flow
rate
> constant and the F28 table of BPC vs EGR.  Value here is .108 across the
> board; larger injectors would mean changing this value to what?  Inverse?

I ended up using .059 across the board for the MSD 50# injectors.  I think
this could vary +- .010  depending on the values in the f29 and f30 tables
and the fuel pressure you are running.   An educated guess would put you
around .084 for the 40# injectors.

Some other things to play with include KAPLL, KAPLH, KAPMIN, F31, F38, and
F92 tables.

I haven't looked at the aftermarket 40# chips, but I believe the major
change was to the BPC only.

HTH,

Jim Sloan
leroy@sunflower.com

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