Re: High Flow MAF revisited - (Porsche 928 voltage MAF)

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

Like I been saying make a Microprocessor controlled devise.   Then you can
do anything you want.
  You can tune any input to any output that way...
Grumpy


| Regarding installing a larger MAF sensor. Bruce is right, there is more to
| it than just installing a larger MAF.  The code only recognizes up to 255
| grams/sec.  So even if you get a maf that will read 500 grams/sec the ecm
| won't.  There are probably some people on this list who could write a
patch
| to make the ecm recognize 510 grams/sec but I am not one of them and it
| would take a tremendous amount of time.
|
| Installing a later model gm freq maf is really involved too, the 165 ecm
| using 89 code doesn't recognize freq or over 255 grams/sec so there are
| several issues involved.
|
| I suspect that if one is really serious it would be easier to convert to
730
| ecm or Speed Pro FI with wide band and be done with it.
|
| Mark
| -----Original Message-----
| From: Thomas Matthews <tmatthew@stny.lrun.com>
| To: gmecm@efi332.eng.ohio-state.edu <gmecm@efi332.eng.ohio-state.edu>
| Date: Sunday, January 16, 2000 6:01 AM
| Subject: Re: High Flow MAF revisited - (Porsche 928 voltage MAF)
|
|
| >I figured that it would take a lot of messing around to get it right...
| >But are they similar in their non linear response?
| >Now if someone had the table of 89 MAF voltage to GPS, then could compare
| >the linearity of the two sensors, and fudge the tables in the ECM to
| >compensate for the difference- I would guess that would leave you pretty
| >close.
| >I guess the real answer would be to build a straight F/V converter, and
| flow
| >the 2 sensors to build a response curve of each, CFM /vs voltage, but I
| have
| >no access to a flow bench...
| >SLP used to sell the 3.5 Bosch MAF with a translator, FYI... If anyone
had
| a
| >contact at SLP or one of these translators that they could reverse
| engineer,
| >that would be a quick solution, but then we're still stuck with the Bosch
| >part... but it has been proven to work.
| >I have a totally virgin NIB Bosch MAF, and I'll purchase a LT1 sensor, if
| >the rest of us can come up with time on a flow bench, a translator, and
the
| >voltage to GPS table in the 89 165 code...
| >Any takers?
| >Tom
| >
| >----- Original Message -----
| >From: "Bruce Plecan" <nacelp@bright.net>
| >To: <gmecm@efi332.eng.ohio-state.edu>
| >Sent: Sunday, January 16, 2000 8:27 AM
| >Subject: Re: High Flow MAF revisited - (Porsche 928 voltage MAF)
| >
| >
| >> Either sensor has the common trait, of not being linear.  Look at K
| >Kelly's
| >> chart.
| >> There ain't no way some simple little V/F or F/V or combination there
of
| >is
| >> going to do what you want, acurately.  One other option, rewrite the
| code,
| >> ya right, like that is easy.  Or use a Microprocessor, and do it
right..
| >> If some one who is really good with code had enough info., that would
be
| >> doable (and with a tad more work we could have a MAP to MAF or MAF to
| MAP)
| >> converter.  Now, the last option would be clever, IMHO.
| >>   Grumpy
| >
| >
|