H20 temperature calibration for Autronic sensor on SM4

[13larry]

Hello, what calibration should be used for the Autronic H20 sensor. I am using NTC but it seems to read about 20 deg C low in the 70 to 85 deg C range when compare to a K type therocouple. 35 deg C and below is correct. Larry

[13larry]

I still have a temp accuracy problem. I am using the Bosch temp sensor provided by Autronic and the correct NTC calibration. There are only two wires, Pin 9 and sensor gnd pin 22. According to the Bosch data sheet the sensor is -40 C to 130 C. I have connected an variable resistor here is the data.

20 C 2.6k ohms
40 C 900 ohms
60 C 318 ohms
90 C 0 ohms.

This is not correct 0 ohms should be 130 C if the NTC cal is correct. I have 5 vdc from the two sensor wires without a sensor so this is correct. The only thing I can think is that my sm4 has the incorrect resistor. Could some please confirm the reading they get with 0 ohms or the wires shorted.

Larry

[Wroom]

This is strange, since the coolant sensor input at pin 9 is working very well on at least all cars i have seen. Both with Bosch sensors, and also compatible sensors of other brands.

[13larry]

I agree that is what I have heard, if you have a chance could you please short the temp sensor and see what temp you get on the laptop. thanks

[MRMRacing]

I can test tomorow, this table is from Volvo and I has my SM4 in that car and the temp is ok.

[13larry]

Thanks Robban, I will check tomorrow. Larry

[-Totenkopf-]

Question, can other sensors be used with the Autronic SM4, ie, would I be able to use the factory sensor in my Toyota MR2 Turbo (3SGTE).

Cheers,

James.

[13larry]

You should be able to calibrate any linear sensor. The problem occurs when you try to calibrate a non linear sensor. If you use your stock sensor you will need to calibrate using a thermocouple. The critical range is the normal operating range of the engine. If it is not linear you should use the supported NTC Bosch temp sensorl.

[MRMRacing]

If it is not linear you use the Linearisation tables. I used a high precision IR temperature meter, pointing directly at the sensor and adjusted while warming up.

[-Totenkopf-]

All sounds too difficult. Think I might just get the GM item or whatever the Autronic specifies. Does anyone have a part number for me. Also, is some sort of loom clip required? (ie, do I need to source a plug for the loom also). Hopefully the autronic item and GM item share the same thread type :)

[RGA-1200]

It's not hard to do a table, but the number as specified in the SM4 manual is Bosch 0280 130 023 or equivalent. A quick google will tell you the thread size.