Date: Mon, 31 Jan 2005 17:14:31 +0000 From: Colin Stamp <colinnospamp.plus.com> Subject: Re: How does the CPU figure out how much gas?
On Sun, 30 Jan 2005 22:23:21 -0500, "WitchDr" <Witch**DRnospamnobulkemail.net.ru> wrote: >Ok, this has probably been asked many times but does anyone have a good idea >how the Saab computer figures out how much fuel is left and how much fuel >gets added? Is their gas gage that good? > As Dave says, the ECU tells the SID how fast it's squirting fuel into the engine. It uses the same sender as the fuel gauge to find out how full the tank is. The MPG calculation only needs the ECU/speedo data and is quite accurate, but the DTE calculation needs the fuel sender info as well. Because of that, it isn't nearly so accurate - mine often reads more when I start up after parking on a hill than when I parked. Very handy as a rough guide though. Cheers, Colin.