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landar

Oat Survey

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I have noticed that the OAT on my '02 always seems to jump by 2 degrees F when it does change. So, I pull out of a warm(er) garage and the readout is 35. As I proceed on my way, the readout goes down due to the frigid winter temps...35, 33, 31, 29, 27, 25, 23. What?? Doesn't it like even numbers? :lol: Same thing on the way back up.

Now, I would think that as the temp sensor cooled it might hit consecutive numbers, but no. I mean, I can see a long sampling period to filter(average) out the changes but this is "redikerus".

If you have an OAT on your LS can you do a check next time out and report back your readout results/behaviour? Tnx

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I think I "fingered" it out. The temperature reading is all done natively in degrees Celsius THEN converted to Fahrenheit. Since Fahrenheit readouts are just a conversion, the ratio is 9/5 or almost 2x. Therefore, the micro is just converting the Celsius and rounding, hence the apparent jump by 2 degrees F. When the rounded C reading is close to an even F reading, the display shows an even value and it jumps by 2 until it gets to a rounded C value close to an odd F integer number and it goes odd for a while.

Lika so:

-2 C = 28.4 F = 28 F

-1 C = 30.2 = 30 F

0 C = 32 F

1 C = 33.8 = 34 F

2 C = 35.6 = 36 F

3 C = 37.4 = 37 F

4 C = 39.2 = 39 F

5 C = = 41 F

That is what is going on. Whew, I can sleep tonight! ;) :whistles:

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I see the same thing in a wide variety of electronics with temperature readouts. The ones that show tenths of a degree will jump by 0.9 degrees F (0.5 degrees C).

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