EasyTherm/SensorTable

Subpage of EasyTherm (see that for the downloads and basic instructions)

Here are a list of temp calibration files for different cars

(see BuildProcedures/SectionThree if you have an v3.x older than 2006 and still don't know what aref=256 means)

Most installs best work with tempsensor_upload.bat 2252 2252 256

that is

Let's say

Plotted with gnuplot using logarithmic Y-scale:

ntc.png

You can also interpolate using data below (for almighty precision):

Celsius   Ohm
-50     150394
-40     75780
-30     39860
-20     21860
-10      12460
0        7352.8
10       4481.5
20       2812.8
25       2252
30       1814.4
40       1199.6
50       811.4
60       560.3
70       394.55
80       282.63
90       206.13
100      152.75
110      114.92
120      87.671
130      67.770
140      52.983
150      41.881

Actual voltage depends on pullup resistor

VEMS v3 uses 2k7 (2700 Ohm) pullup to +5V which gives voltage:

U= 5V / (2700 / NTC_Ohm_at_given_temperature + 1)


If you have doubts, provide measurement(s) so we can help you select the best temperature curve. Actually with the common ntc type sensor, just one temperature point is sufficient (easiest with cold engine when sensor temperature is same as environment)

Coolant Sensors

Car MakeCar modelEnginesensor partno#Pullup Rcalibration file link
Bosch (Volvo, BMW, VAG, etc...) ... ... unknownstandard 2k7 See Bosch below
[www.vems.hu/files/sensors/NTC/air_clt_hiresistance_sensor.zip hi resistance sensors if you really stick to 2k7 pullup; better change pullup instead

Air Temp Sensors

Car MakeCar modelEnginesensor partno#Pullup Rcalibration file link
Bosch (Volvo, BMW, VAG, etc...) ... ... unknownstandard 2k7 See Bosch below
Audimany 5cylAAN/ABY/ADU/3B/etc...PTC type, appr 500 Ohm at roomtemp429..430 Ohm[PTC_airdenfactor_430_Ohm_pullup.txt]. For dead-on calibration, you can choose from the PTC series, Marcell found PTC_aref260_425 is best for his Audi PTC. Note that the second number is higher for higher PTC value (or lower pullup)

BOSCH sensors

For the classic 2057 Ohm (@T=+25C) NTC type sensor (often closer to 2063 Ohm in practice though difference is negligable), 2063/263 (or 256 or 268) is best match.

Most classical BOSCH NTC curve used from early 80s up to nowdays. No matter it is Volvo, Audi, Mercedes, Volksvagen, BMW etc - all of them had or have similar sensors.

NTC_BOSCH2.jpg

Source: http://www.bosch-motorsport.de/pdf/sensors/temperature/NTC_M12.pdf

Both ...2063_256.hex and ...2252_256.hex give some degries mismatch at environment or engine operating temperatures. At tuning it is not heavy importance, but if LCD is used this is very welcome to see believable values on it.

Same isue had Miska Peippo described here: http://www.vems.hu/wiki/index.php?page=MembersPage%2FMiskaPeippo%2FAudiSSix