-----Original Message----- From: Dave Zug [mailto:dzug@delanet.com] Sent: Saturday, June 17, 2000 4:07 AM To: gmecm@diy-efi.org 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. yes this is why it is taking so long... ps the maf will read up past 255g/s actualy if you apply 10v (safely it will go from 20g/s to 620g/s @ 9.8v tested on flow bench... will post the excell graph... finer resolution is good,, could help eliminate some of the lag that bruce is talking about. 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 ;-)) got one will post.. been nusy.. had wisdom teeth pulled.. ouch look like chipmunk... but once this is done.... i will pass to everyone.. then it becomes easy esp for guy who wants to "stick " a huffer on it.. :) ----- 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
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