Re: Changing 165 / Nother Q

["Dave Zug." <dzug@delanet.com>]

My particular interest in holding onto MAF is that it keeps my car stock
appearing, a trait I hold on to after owning a GN. This car is the "peak"
year for the MAF, and is a genuine IROC (not that rare, but still, dont want
to alter it's core being) I could hide the MAP and pull the air thru a MAF
but, well, I still gotta keep the car marketable and okay for a GM tech to
work on if needed... besides, I have a 60 hour job that has nothing to do
with cars.. this is all spare time hobby stuff.

Hey was the very limited 90 IROC a MAP system?? hmmm...

Gutting the MAF won't change the BLM's when no other change is performad?
more port area = lower velocity for the same amount of air passing = more
air for an equal velocity (for gutted vs ungutted) = incorrect (low) reading
with gutted version = lean prediction by computer, thus BLM's rise, is the
way I see it. I definetly agree that what I am living with is wrong, hence
me trying to find out if anyone has verified flow re-cal on a gutted MAF, so
I can move towards correct. I have no flow equipment.. just a 1 car
cluttered garage, shop vac, DMM, and a little spirit ;-)




----- Original Message -----
From: Bruce Plecan <nacelp@bright.net>
To: <gmecm@diy-efi.org>
Sent: Tuesday, June 20, 2000 8:00 PM
Subject: Re: Changing 165 / Nother Q


> The porting shouldn't really effect much of anything having to do with the
> O2, IMHO.  The flow at idle is like 10ish grms/sec., vs 255 at WOT.  I'd
> guess that at less then 100 grms/ sec your at a high enough TPS to be in
PE.
> If a fuel pressure corrected anything it was the disturbed air flow and
> inaccurate reading from the MAF.
> Put another notch in the belt for modified engines and MAP.
> Two wrongs don't make a right here either, with the info here, I just
can't
> see why not just do it right the first time.  For all the time dinkin with
> the MAF you've wasted the only advantage it had.  As a tuning tool like
> Scott S is using it great, but I still ain't sold on it being the ultra
> setup, when you run out of resolution with it.
> Grumpy
>
>
>
>
> > If mine pegged I'd have a problem.. it does NOT peg (yet).
> >
> > If a gutted MAF was done at the same time as a FP increase, o2 and thus
> > BLM's may stay in balance.  What you have then is an incorrect air
reading
> > as well as an incorrect fuel reading, both incorret by the same
> proportion,
> > in the same direction, the net result is "it runs pretty darn good".
(did
> I
> > get that right?)
> >
> > The more retentive tuning guys go nutz over this. Yes I would go nutz
over
> > it if I thought I knew what I was doing more, then I could make it
right,
> > but good 'nuff seems to be the order of my ways. ;-)
> >
> > I was out to try some fancy stuff with a 'holy' MAF, but the
supercharger
> > crapped out and I never followed thru.  add it to the list of good
> > intentions fallen flat.
> >
> > ----- Original Message -----
> > From: Mike Rolica <mrolica@meridian-mag.com>
> > To: <gmecm@diy-efi.org>
> > Sent: Tuesday, June 20, 2000 11:33 AM
> > Subject: RE: Changing 165 / Nother Q
> >
> >
> > > or how bout a EEEEEEK ford one :)
> > >
> > > -----Original Message-----
> > > From: Romans, Mark [mailto:romans@starstream.net]
> > > Sent: Saturday, June 17, 2000 12:41 PM
> > > To: gmecm@diy-efi.org
> > > Subject: Re: Changing 165 / Nother Q
> > >
> > >
> > > Dave:  I have a ported maf on my Vet.  I have had to adjust the
> > calibration
> > > only in the smallest calibration table.  BL has stayed close to 128 at
> all
> > > other areas so I am assuming that the calibration has not been thrown
> off.
> > > The problem is once again in that the software doesn't read above 255
> > > grams/sec.
> > > I have thought about, but taken no action on looking at the Porsche
928
> > > bosch maf sensor.  It is supposed to have a  larger ID and flow more
> air.
> > I
> > > would attempt to adjust the injector constants to make fuel match up
> with
> > > air flow.  I would lose some accuracy, but it would be no different
than
> > > what the 730 does.
> > > Mark
> > >
> > > ----- Original Message -----
> > > From: "Dave Zug" <dzug@delanet.com>
> > > To: <gmecm@diy-efi.org>
> > > Sent: Saturday, June 17, 2000 1:07 AM
> > > Subject: Re: Changing 165 / Nother Q
> > >
> > >
> > > 400000000000000000 / 256 = 156250000000000 (close)  G/S per single
unit
> of
> > > resolution on the sensor....
> > >
> > > Your point is understood,  but I'd use MAP for the jet engine ;-)
> > >
> > > converting to 16 bit would be useful only if the sensor range was also
> > > raised.  If you turn an 8 bit value into a 16 bit, it just gives you
the
> > > ability to see the sensor value as more tiny-er steps... not higher
> > values.
> > > you would have to change the sensor range at the same time to be able
to
> > > read more air.  (9 bits will get you to 512 steps,  BTW).  sorry this
> may
> > be
> > > out-of-place rambling, I don't understand how this is done very
easily.
> IN
> > > the code, the A2D would see a maxxed input, translate to FFh, and that
> may
> > > trigger some creative code to say "go to the high table" but the input
> > still
> > > will be pegged.  you'd almost have to electronically reduce (re-scale)
> the
> > > voltage input from the MAF to the ECM, then allow the internal 9-bit
(16
> > > bit) value to read 255 when the voltage level was at 4v or something,
> > then
> > > have the internal 9-bit read 320 at 5v... a second "high" table would
> have
> > > entries that were up to (320 minus 255), and would be in use only when
> the
> > > "high flow" bit (9th) was lit.
> > >
> > > oooh my brain, the POOR '165  ;-)  Please, as always... someone add /
> > > correct me so I don't confuse others browsing the archives.
> > >
> > > I have used the RPM based fuel tweak to compensate for what the MAF
> can't
> > > see.  Its a trial and error method, but I got it to work out when I
had
> > the
> > > Supercharger on.  I started reeeal rich, and used o2 to make sure I
> wasn't
> > > lean, but I should have backed it up with an EGT.
> > >
> > > Makes sense to me that if you can increase the size of the MAF (not
> saying
> > > anything new here) that the readout for a given flow rate will
decrease
> > > exactly proportionally with the increase in orifice area.  the big job
> is
> > to
> > > go thru EVERY calculated value (on chip) and every comparison made to
> > those
> > > values, and adjust them accordingly.  i.e.  trip into PE mode at a MAF
> > value
> > > of 40(d) insted of 55(d) because now 40 represents 55 g/s and 255
> > represents
> > > 320 g/s (or whatever math...)
> > >
> > > To MY Question:
> > >
> > > Has anyone scientifically measured the effect on readings between an
> > > unported, stock, screened MAF and a ported (no sink) and un-screened
> MAF?
> > I
> > > figgered roughly the percentage of area opened up, and a little tweak
> for
> > > the reduction in air turbulance and went with that to re-calibrate the
> MAF
> > > tables. I figgered a shop vac and a y-pipe and a volts meter would
give
> a
> > > ratio as well.  anyone done it?  share?  of coarse the voltage reading
> > will
> > > be lower for the gutted MAF,  but it would be cool to have a graph of
> each
> > > at all flow levels ;-))
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: Mike Rolica <mrolica@meridian-mag.com>
> > > To: <gmecm@diy-efi.org>
> > > Sent: Thursday, June 15, 2000 1:05 PM
> > > Subject: RE: Changing 165 fuel delivery was "General tuning question -
> > fuel
> > > economy"
> > >
> > >
> > > Argggg.. yes it can pull in 40000000000000000000times more air  but as
> > long
> > > as you are in the range of the maf... ie below it's max sensing cap ie
> 254
> > > g/s  then the maf is fine.
> > >
> > > Senario 2.. lets say at 2500rpm  and ½ throttle, and you are pulling
> > 255g/s
> > > then the ecm thinks this is max air it can get....so it cant regognize
> and
> > > more air.... That is why I would like to create a patch to use either
2
> > > tables or go 16 bit!!!!
> > >
> > >
> > > <BIGSNIP>
> > >
> >
>
> --------------------------------------------------------------------------
> > --
> > > To unsubscribe from gmecm, send "unsubscribe gmecm" (without the
quotes)
> > > in the body of a message (not the subject) to
> majordomo@lists.diy-efi.org
> > >
> > >
> >
>
> --------------------------------------------------------------------------
> > --
> > > To unsubscribe from gmecm, send "unsubscribe gmecm" (without the
quotes)
> > > in the body of a message (not the subject) to
> majordomo@lists.diy-efi.org
> > >
> >
> > ----- End of forwarded message from owner-gmecm@diy-efi.org -----
>
> --------------------------------------------------------------------------
> --
> > To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
> > in the body of a message (not the subject) to
majordomo@lists.diy-efi.org
> >
> >
>
> --------------------------------------------------------------------------
--
> To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
> in the body of a message (not the subject) to majordomo@lists.diy-efi.org
>
>

----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo@lists.diy-efi.org