Re: Changing 165 / Nother Q

["Bruce Plecan" <nacelp@bright.net>]

> 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..

If he doesn't know the difference tween a 89 and 90 system he's a parts
exchanger, notta mechanic.

. 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...

??, all the 90s V-8 F Bodies are MAP

> 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.

At less then WOT when not in PE, the throttle is limiting the air flow not
the MAF.  Veleocity thru the MAF doesn't matter.  The sensor is a hot
wire/foil,
Grumpy

 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>
> > > >
> > >
> >
>
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