Help needed : CHT calibration with Megasquirt

[kamaro]

I've been using a Microsquirt ECU with my 3.2 Carrera engine for a while now and been very happy with it, except for the calibration needed to read the correct engine temp off the CHT, I have tried so many different calibration numbers and all failed to give me even a close temp number! .. it seems the CHT sensor is far from linear .. Can any one share his calibration numbers with me please?

[FrankM_]

https://forums.pelicanparts.com/porsche-911-technical-forum/1052215-verify-my-cht-sensor-test-results.htmlSee this post, it links to the datasheet from Bosch.


Sent from my iPhone using Tapatalk

[spuggy]

Originally Posted by kamaro

I've been using a Microsquirt ECU with my 3.2 Carrera engine for a while now and been very happy with it, except for the calibration needed to read the correct engine temp off the CHT, I have tried so many different calibration numbers and all failed to give me even a close temp number! .. it seems the CHT sensor is far from linear .. Can any one share his calibration numbers with me please?

The Bosch NTC sensor family is nominally 2.5 KOhms @ 20C, +/- 5%. Response of an NTC sensor is not linear - eg it is a curve, not a straight line,

Bosch datasheet gives following resistance values:



I don't know what the Microsquirt program wants/needs (eg voltage or resistance), and you don't say. Motec has "Bosch 2.5K" as a standard type, although they do provide a voltage table for manual calibration in their datasheet: https://www.motec.com.au/filedownload.php/55001_water_temp_sensor_datasheet.pdf?docid=1326:

which looks like this:


The Bosch datasheet used to be here (checked; it still is): Temperature Sensor NTCÂ M12

This thread has the resistance values from the factory shop manual as well: Verify my CHT sensor test results