Info seems to be a bit spread around on this, but I would like to come up with some good equations for water and air temp.

I got my pocketlogger out today and did some testing. The 1G DSM table that was posted in another thread seems to be dead on perfect.
I converted the hex to decimal and the temps to fahrenheit. I will attach the txt file to this post.

Some of the equations that have been posted so far are very good over the broad range, but fall short in the pinpoint accuracy that I am looking for in the "working range" of the sensors.

This is the best I could come up with for air temp:
-0.0000309xxx+0.01202xx-2.3483x+241.776

It is withing +/- 1 degree from 40 to 150 degrees

The problems start when trying to deal with the water temp.
This is the best I got:
0.000002221xxxx-0.0008724xxx+0.11856xx-7.638x+325.3667

I realize that it is stupid to use a 4th degree polynomial here, but my calculator will not do quintic regression. I am not smart enough to do it by any other means. Hopefully one of you math folks can jump in here.

This equation is very accurate over the "sweet spot" but becomes insanely inaccurate at low temperatures. At 0deg F, it is off by about 100 degrees

It gets into my target of +/- 1 degree at about 140 degrees, and is good all the way up to 250 degrees. That covers the important range of the sensor, so it is good enough for me. If someone could come up with a precise 5th order polynomial then that would be great.

If anybody wants to play with these, I will attach a data.xml (you will need to unzip it). It is otherwise a standard data.xml from a fresh .9 evoscan install.

A couple observations I made:
crusing water temps were 179-183 degrees (75 degree air temps)
the fan seems kicks on at exactly 190 degrees
With the stock air box, cruising at 75mph, air temps were 79-84 (4-9 degrees above outside air temp)
Air temps climbed to as high as 125 when stopped and idling

 

I thought I did a pretty good job with the correlations I posted a week or so ago.

 

those look good don't know how i missed them. guess i wasted my time.

i am not a software guy, but you would think that since we have all of the values....one could just implement a lookup table of sorts in the software so things would be exact. I dunno.

 

Actually, I took another look at the intake air temp correlation and decided that it didn't need to be fit all the way to 360F. After watching my air intake temps for a few days, it seems like the temperature is unlikely to exceed 250F (if even 200F), so I refit it to cover from 50 to 250F, and now its a bit more accurate in the 100F temperature range:

-0.00000001300xxxxx+0.000006657xxxx-0.001341xxx+0.1353xx-7.874x+336.1

 

Thanks for the updated definitions guys.