Re: Changing 165 / Nother Q

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

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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