Re: Off idle transistions

["Dominic Sorresso" <surrexi2@home.com>]

Shannen,

That's great info and I appreciate you sharing it with me. I think you know
I have the 747 ECM but the chip currently in it is not the stock config from
TCity. They sent me another one once I was able to report back on the result
of the drag strip and dyno runs. I believe that the stock chip was causing
the knock retard to be invoked big time at the top end especially in the hot
weather I was running in. I am hoping to get a bin file of the stock chip so
I can compare to what I have now because the stock settings didn't seem to
be that rich. Having said that, it appears that part of the rich condition
both at cold start and cruise was the fault of unbalanced TBI units which
have since been balanced. Yesterday, I bumped Fp to 10.5 and it seemed to
make idle smoother although there are still times when idle will hang up
there until IAC's bring it back down.
And speaking of balancing TBI's, Bruce, you mentioned that your Xfire had
the 2" units as does mine. Were you able to retain the slot in the venturi
used for the balancing of the units? If not, what did you use? I drilled
vacuum port which was in base and connected to center port of TBI. I am
assuming that it is now reading manifold vacuum. A water manometer is
useless.

Dominic
----- Original Message -----
From: "Shannen Durphey" <shannen@grolen.com>
To: <gmecm@diy-efi.org>
Sent: Tuesday, August 15, 2000 6:48 PM
Subject: Re: Off idle transistions


> Dominic Sorresso wrote:
> <snip>
> > Also, cold start
> > seems to be richer than necessary until it goes into CL.
> >
> > Dominic
> Dominic, I've never seen a crossfire car that didn't run rich in OL
> with the original ecm.  Most are so rich that they will foul one or
> even two plugs.  It would make sense to think
> TC is using the stock calibration as a base for their fuel and spark
> tables.
>
> Regardless, when I converted my pickup xfire to 7747, I found that the
> stock (7747) fuel tables for low MAP were very close, but that I've
> had to add additional fuel to prevent backfire during acceleration,
> when not in pe.  I started with a stock 350 cal, changed the injector
> constant, and went from there.  One other thing I did was collect as
> many manual trans 7747 calibrations that I could,  plugged each one
> into the truck, and picked the one that idled the best.  Something
> about re-inventing the wheel... From there I set the injector constant
> so it matched my engine displacement and injector size, and started
> driving around.  I kept track of bl and integrator #'s, and moved the
> injector value a little bit more to reduce the CL corrections.  After
> that, everything has been done in fuel and spark tables.
>
> At this point I'm wishing that I'd had springs added to the 57 spec
> clutch.  She'll start to slip if I'm not careful.  It was never meant
> to be this way...
> Shannen
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