Re: General tuning question - fuel economy

[romans@starstream.net (Romans, Mark)]

At this point I wouldn't worry about fuel economy per se.  I would try to
get the BL to stay close to 128 in as many bl cells as possible.  Then once
that is done, go leaner on the commanded afr for cruise and it will be more
accurate.
Mark
----- Original Message -----
From: "Marteney, Steven J." <smarteney@xlvision.com>
To: <gmecm@diy-efi.org>
Sent: Wednesday, June 14, 2000 9:23 AM
Subject: RE: General tuning question - fuel economy


> Yet again, unfortunately, one of the first things I did was raise the fuel
> pressure.  It's set at 50 psi.  I also "arbitrarily" advanced the timing
and
> ended up setting it right at 0 base advance.  Setting it at 8 drastically
> improved low-end but fuel economy at cruise wasn't much improved, maybe
0.3
> mpg but my mpg measurements fluctuate +/- 0.5 or more.
>
> Steve  (Just having trouble seperating all the variables, but I'm getting
> there.)
>
> -----Original Message-----
> From: romans@starstream.net [mailto:romans@starstream.net]
> Sent: Wednesday, June 14, 2000 11:44 AM
> To: gmecm@diy-efi.org
> Subject: Re: General tuning question - fuel economy
>
>
> Raise your fuel pressure.  This should bring your bl down a bit.  When it
> gets to be interesting is when the bl is high in one part of the map and
low
> in another.That's when I edited the values in the maf calibration.  (165
> ecm).
> Mark
> ----- Original Message -----
> From: "Marteney, Steven J." <smarteney@xlvision.com>
> To: <gmecm@diy-efi.org>
> Sent: Wednesday, June 14, 2000 7:47 AM
> Subject: RE: General tuning question - fuel economy
>
>
> > Unfortunately, the BLM is typically sitting around the maximum.  I've
seen
> > it at 160, but it's typically around 145-150.  This says to me with the
> > bigger cam, it saw it was too lean (more airflow) and therefore it gave
it
> > more fuel, hence less gas mileage.
> >
> > Steve
> >
> > -----Original Message-----
> > From: Squash [mailto:realsquash@yahoo.com]
> > Sent: Tuesday, June 13, 2000 5:04 PM
> > To: gmecm@diy-efi.org
> > Subject: Re: General tuning question - fuel economy
> >
> >
> > I'm not sure how that ecm works (165=C3?), but is it possible that the
BLM
> > is sitting at the
> > minimum value?  That would mean it's trying to lean it out, but it
stopped
> > because of the limit.
> >
> > Squash
> >
> > --- "Marteney, Steven J." <smarteney@xlvision.com> wrote:
> > > Not having really any engine "tuning" experience I stumble on some of
> the
> > > basic concepts (such as when to add spark advance).  My rebuilt 350
TPI
> > > F-body gets about 20% less highway gas mileage with its bigger cam (GM
> > ZZ3)
> > > and stock computer.  I figure more air in at X rpm requires more fuel
to
> > > appease the O2 sensor, hence gas mileage goes down.  How do I
> compensate,
> > or
> > > can I?  I noticed there are some Hiway mode parameters, such as Hiway
> > spark
> > > add (?), in the 165 ECM that I could take advantage of.  Or, is the
only
> > way
> > > to get better mileage mean changing the target AFR?
> > >
> > > However, I also thought that this engine cruises at about 2200 rpm on
> the
> > > highway at 75 mph.  I'm wondering if the different cam (and valve
> timing)
> > > has defeated the ram tuning effect of the runners and made the engine
> less
> > > efficient on the highway.  Any thoughts?  I'd appreciate a little
basic
> > > help.  Since this car is my daily driver (70+ per day) I'd like to
keep
> > fuel
> > > economy in mind when tuning.
> > >
> > > Thanks,
> > > Steve Marteney
> > >
> --------------------------------------------------------------------------
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