Date: Fri, 25 Jul 2003 13:00:00 GMT From: hohnopsamlid.invalid (Goran Larsson) Subject: Re: Gas economy
In article <t40Ua.37310$Ii1.830nopsam02.bloor.is.net.cable.rogers.com>, Smoky <gopher_gutsnopsamail.com> wrote: > The EDU "does not" measure > anything. It is just an electronic "best guess" and always assumes a > perfectly tuned engine the same as the day it was made. The EDU measures two signals for its fuel consumtion numbers. One signal is the distance driven, i.e. the same signal that is used by the speedometer, odometer, and some other functions in the EDU. The other signal is the time the injection valves are open. As the volume that passes through the injection valves over a certain time is known it is easy for the EDU to calculate the fuel volume used. Later Saabs with Trionic and SID does it slightly differently. The SID receives the fuel volume (or, IIRC, the weight in mg) over a communication bus from the Trionic engine management computer. If the tyre/tire size is correct then the fuel consumption numbers displayed by the EDU or SID should be very accurate. Calling it just a guess is far from the truth. -- G–ran Larsson http://www.nospam.com/saab/
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