Voltage based CLT sensor, how to?

[mickeymarrows]

I'm using tunerstudio (registered) with MS and am now adding a Megashift TCU to control my Audi transmission.

The problem I have is the temp sensor is built into the internal flexible circuit and rather than a thermister connected to ground it's connected to the 12v supply!

I have a set of resistance values for the thermister (taken between the 12v pin and sensor pin with the TCU disconnected) of 247000ohms@20c, 48700ohms@60c and 7400ohms@120c and have created a voltage divider circuit to keep the resulting voltages below 5v.. But what can I do to get Tunerstudio to convert those Voltages back to ADC values and then temps?

[Brian H EFI]

Do you have a .inc file with the values needed for that sensor or did you just get those three temp. readings with the plan to use a three point interpolation like the
temp. sensor calibrations in TS?

If you do have a .inc file for that sensor could you please send it to me at support@efianalytics.com and I will edit it to work with TunerStudio and make the custom.ini
you will need to read the temperature from the sensor.

Brian H

[mickeymarrows]

Hello Brian,

I don't have an inc file, just those 3 resistance values taken from an Audi workshop manual.

Lance has been trying to help over on the GPIO:
http://www.msgpio.com/forums/viewtopic.php?f=4&t=873

But that method unfortunately reports 60c when it should be about 17c..

[mickeymarrows]

Hello Brian,

Can you offer any help on this? its a bit of a showstopper for us.

Basically Lance worked up an equation for us which appeared to work (at room temp).. but this weekend Scott was the first to actually run the transmission and Tunerstudio appears to invert the temp.. i.e as transmission temps increased then Tunerstudio displayed them as decreasing..

[Matt Cramer]

The first key is to put together some sort of table of voltage vs temperature - are you able to make such a thing?

[mickeymarrows]

Hello Matt, yes we have 3 points of temp/resistance for the thermister (from Audi) and therefore the steinhart hart coefficients.. So from there we can generate a table. Its all in the thread above.

In the thread above Lance worked back to calculate values to use in Tunerstudio.. Which appeared to work at 20c (68f)..but..

[mickeymarrows]

I've generated a temp/voltage/resistance table as requested..

Its attached as an .msq but its actually a .xlsx file.

[Jay_D79]

Is there anything stopping you from adding a regular thermistor type sensor to the side of the transmission pan (or other threaded port on the case), similar to what you would do if you were adding an aftermarket temperature gauge?