Date: Thu, 07 Sep 2000 06:47:28 -0400
From: Geoff Waters <grw888nopsamel.net>
Subject: Re: How does SID work?


I don't have my manual handy, but in my 94 900S (with the basic SID) and 96 900SE (with the fancier SID 3) I believe they update the mileage and fuel consumption data every 15 seconds (or is it 30?), with the DTE figure based on the average of the most recent twenty minutes data. In my 900SE, when the DTE hits the single digits, it takes about 16 gallons to fill it (nil or minor topping-off). So does that mean there are about two (18-16=2) gallons left. I've never tried running the DTE number into the minus.... /Geoff Jack B wrote: > Philip G. Schroeder <schroedpnopsamyette.edu> wrote: > > how often, is the DTE (distance to empty) calculated? My fuel gauge > > stays on full for the first third or so of a tank and then drops > > relatively fast to empty for the rest of the tank. So, the 3/4, half and > > 1/4 readings seem meaningless. > > I wonder if that's the GM influence creeping up. I read several years > ago that when Cadillac introduced digital gauges, they received a rash > of customer complaints regarding fuel economy. You see, the digital > gauge was so accurate that it had one "bar" for each gallon in the tank. > It's almost impossible to completely fill a tank with the vapor-recovery > hoses... so, about five or six miles after driving away from the pump, > the tank would drop below one gallon "gone"... and customers were > bewildered to see the gauge drop from "F" so quickly. > > GM consulted psychologists about the problem, and their "fix" was to > put a bit of logic into the gauge. For the first quarter of the tank, > the gauge reported 1/4 of the actual consumption. For the second quarter, > it was half - so the gauge showed 3/4 when the tank was 1/2 full. After > the half-tank mark, the gauge became progressively more "pessimistic" > until, at the 1/8 tank level, it was showing "E". > > The customers were thrilled.

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