MembersPage/GrmRacer/BoschCltSensor

Just some readings from a new Bosch Coolant Temp sensor (88 16v scirocco)


degrees C   kOhms
-20	    11.20
-10	    10.00
9    	    3.36
20	    2.42
30	    1.72
40	    1.16
60	    0.72
69	    0.63
74	    0.59

At 25C is appr. (2420 + 1720 ) *0.5 = 2070 Ohm, likely 2063 Ohm NTC.

so depending on your AREF you'll need 2063_256 or 2063_287 see EasyTherm

You asked on irc what NTC the default firwmare has. I checked. NTC's nominal value is the resistance at 25C. So I looked for the 25C point in the matfactor table of vems.hex:

  • 0x88 position
whats in firmware

at :100280007A7979787777767675747473727271701B

Since the NTC makes a voltage divider with a 2700 Ohm (onboard) resistor, at 25C the NTC resistance is (proportional to) 0x88 when the 2700 Ohm is (proportional to) 256-0x87=0x78

This reads: 2700/0x78 * 0x88 = 3060 Ohm nominal value

You likely want to hexpatch your firmware for an NTC of lower nominal value (closer to your 2063 Ohm NTC). It takes 2 mins to download/unzip and 2 mins to parameter hexpatch.exe and 2 mins to upload new firmware. See EasyTherm