Fuel tank capacity PID changes on same car?

Wondering if anyone else encountered this and what is the logic / mechanism behind it. On the same car, two consecutive data logs back to back, the fuel tank capacity goes from 18.6 to 18.8. Unless it is some weird glitch the only thing that would explain it is if it was calculating it off pressure somehow...?

What vehicle is it?

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Originally Posted by kevin87turbot

What vehicle is it?

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My 2012 Caprice V8 logged by MPVI2

I do notice in a Caprice tune file I have on hand, since you didn't bother to post yours, that it has Capacity = 18.57 and Capacity Gauge = 18.76, the two values are suspiciously similar to the two numbers you saw. Still cannot figure out why logging that info would be useful for anything though.

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Originally Posted by blindsquirrel

I do notice in a Caprice tune file I have on hand, since you didn't bother to post yours, that it has Capacity = 18.57 and Capacity Gauge = 18.76, the two values are suspiciously similar to the two numbers you saw. Still cannot figure out why logging that info would be useful for anything though.

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Attachment 116974

I logged it because I am a nerd and I want to run exactly 1/4 tank of stated capacity next 1/8 mile pass. It is a reference point. And an opportunity to ask questions and learn.