max Posted March 15, 2020 Report Share Posted March 15, 2020 hello ive fitted the above sensor to monitor fuel and oil pressure and temp ive found a calibration page for the temp part of it and it states the values with a 4.6k pull up resistor how do i go about adding the pull up resistor to the wiring to get it reading correct. do i just use the resistor to bridge between the 5v and the temp signal wire thanks Quote Link to comment Share on other sites More sharing options...
Apex Speed Tech Posted March 16, 2020 Report Share Posted March 16, 2020 Before you do that, do you have any Analog Temp inputs available? I may be mistaken as I haven't done it myself, but can't Cal Table 1 be set to Ohms so you can use the internal pullups? The calibration for that part number in Ohms vs Degrees C is easily google-able, though again I haven't tried it myself. If you are using a standard analog input and have a 0-5V calibration with a 4.6k pullup to 5V that you want to use, then as you said, terminate 1 end of your 4.6k resistor to sensor signal and the other to +5V. Cheers, Neel Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 16, 2020 Report Share Posted March 16, 2020 The Bosch combined press/temp sensors use the "Std Bosch NTC" calibration. If you connect it to a AN Temp input then you dont need any extra pullup, just select Bosch from the list and it will work. If you are out of AN Temp inputs and want to connect it to a AN Volt channel then I would suggest a 1K pull-up rather than the 4.6k as it will give better resolution at normal operating temps. Cal table attached below you can import into CAL1, 2 or 3 if you are using an AN Volt input. Calibration Table Bosch 026.lte Quote Link to comment Share on other sites More sharing options...
max Posted March 16, 2020 Author Report Share Posted March 16, 2020 ive connect them to an temp 3 and an temp 4 and on the standard bosch ntc calibration there reading incorrect when the engine temp is around 70 they were both reading around 15. the pressure sensor part of the sensor is wired to an an volt channel using the 150 psi ti calibration and works fine i will try your calibration table and see what it reads then Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 16, 2020 Report Share Posted March 16, 2020 3 minutes ago, max said: ive connect them to an temp 3 and an temp 4 and on the standard bosch ntc calibration there reading incorrect when the engine temp is around 70 they were both reading around 15. the pressure sensor part of the sensor is wired to an an volt channel using the 150 psi ti calibration and works fine i will try your calibration table and see what it reads then My cal is not going to make any difference, it is the same as the built-in Bosch cal. Can you attach the tune. Do these sensors have a resistance of about 2500ohms at 20deg C (room temp)? Quote Link to comment Share on other sites More sharing options...
max Posted March 16, 2020 Author Report Share Posted March 16, 2020 will measure the resistance on them later when I'm at the car. I can't even say it's the wiring as the pressure part of the sensor shares the 5 volt and sensor ground and that works fine Quote Link to comment Share on other sites More sharing options...
max Posted March 16, 2020 Author Report Share Posted March 16, 2020 with the dash showing 40c the resistance of the bosch sensor is 0.875 on the oil temp and 1.000 ohms on the fuel temp but I have no other way of measuring the fuel temp at those ohm readings the oil temp is reading 28c and the fuel temp is reading 21c. and voltage wise the temp is going high to low were as the pressure goes low to high Quote Link to comment Share on other sites More sharing options...
Apex Speed Tech Posted March 16, 2020 Report Share Posted March 16, 2020 4 hours ago, max said: with the dash showing 40c the resistance of the bosch sensor is 0.875 on the oil temp and 1.000 ohms on the fuel temp but I have no other way of measuring the fuel temp at those ohm readings the oil temp is reading 28c and the fuel temp is reading 21c. and voltage wise the temp is going high to low were as the pressure goes low to high I can concur with Adam, I didn't check before but the datasheets I found for the 0261230340 match the temp cal for the 026. For a Bosch 026 sensor, 1 ohm is between 120 and 130C. Are you reading those values across the sensor not plugged into anything? http://www.bosch-motorsport.de/content/downloads/Raceparts/Resources/pdf/Data sheet_70101387_Temperature_Sensor_NTC_M12.pdf Where is your dash reading from? Quote Link to comment Share on other sites More sharing options...
max Posted March 16, 2020 Author Report Share Posted March 16, 2020 dash reading is from a stack dash with its own pressure sensor i will go back tomorrow and remove one of the sensors for testing. its strange from cold they both start off reading around 10c then when coolant temp gets up to 80c it only gets to around 18c then i turned it off went back to it 20 mins later then the stack dash was showing oil temp at 40 and the bosch sensor was now showing 28 . but if you just let the engine run it wouldnt get past 20 and what else is strange is the fuel temp is pretty much the same as the oil temp Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 17, 2020 Report Share Posted March 17, 2020 One common trap to be aware of with these sensors is many of the mating 3rd party trapez connectors for them have the pin cavities numbered differently. So make sure it is pinned by the diagram on the sensor datasheet, not using pin numbers. Quote Link to comment Share on other sites More sharing options...
max Posted March 17, 2020 Author Report Share Posted March 17, 2020 sorted it i had a stupid moment the fuel temp was working all along and the oil sensor was remote mounted so it measured pressure fine but as it had no flow its wasnt picking up the change in temp swapped a few sensors around and it seems to be working correct now thanks for the help Quote Link to comment Share on other sites More sharing options...
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