Changing 165 / Nother Q

[Bruce Plecan]

Urrrgh,
but no different than what the 730 does.
At that stage it's all in the calibration
Grumpy



> 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 at delanet.com>
> To: <gmecm at 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 at meridian-mag.com>
> To: <gmecm at 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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