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Old 10-27-2008, 10:03 PM   #2 (permalink)
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Join Date: Dec 2007
Location: Southern California
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1999 Saturn SW2 - '99 Saturn SW2 Wagon
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regor -

I suspect the 9999 is not a problem per se. When you take your foot off the accelerator, your cars cut off fuel to the injectors. In this situation you have "infinite MPG" :

MPH / GPH = MPG => 50 MPH / 0 GPH => Infinity MPG

The Scangauge's don't have a symbol for infinity, so they display the largest number on a 4 digit display, 9999.

This could also be an artifact of the algorithms. For instance, if I were programming the scangauge, I would be watchful for divide-by-zero errors as displayed above. In that situation, I would probably divide by a super-teeny constant, say 0.0000001 GPH, which would yield "infinite MPG" for practical purposes :

50 MPH / 0.0000001 GPH = 500,000,000 MPG (aka infinite for comparison purposes)

Since my above example can yield "different infinities", they probably compromise and just display 9999 in all cases.

I saw this exact-same behavior on a Renault Megane diesel in Europe. I don't have fuel cutoff in my Saturn. You should be happy!!!!!!

In terms of the second problem, that's really whacky!


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