Select Temperature Sensor Calibration (Select)

Refer to the ‘Temp sensor calibration’ panel as shown below:

Each temperature sensor input on the Select ECUs (Water Temperature, Air Temperature, Aux Temperature) has its own calibration table. There is also a tickbox to specify whether the temperature inputs are ‘biased’ (pulled-up) inside the Select ECU (this will usually be ticked, except for some piggyback Select Plug-In ECUs which share temperature sensors with the factory ECU).

You may choose to enable a firmware-based filter (with a 1 second time constant) for the temperature readings, to make them more stable.

To Calibrate the temperature sensors…

The default table in the ECU suits a common type of sensor. In practice, it is easiest to do a ‘sanity check’ when the engine is stopped (and verify that it reads approximately ambient temperature), and then verify the readings with a thermometer as the engine warms up. This is most easily done with the water temperature sensor.

To calibrate the sensors properly, you must perform a temperature sweep, and populate the calibration table (see below):

It can be easiest to start at the hottest temperature by heating the sensor up to just above the maximum temperature (125°C). Stop heating the sensor.
With a thermometer installed, monitor the temperature of the sensor.
As the temperature falls through its operating range, ‘learn’ the ADC reading for each appropriate temperature by clicking on the temperature number (you will see the cursor changed to a pointing hand).
Ensure that the sensor cools slowly so that the thermometer is reading the sensor temperature accurately. This may be facilitated by heating it gently, or immersing the sensor and thermometer in oil or water (not water at 125°).

Once the sensor gets down to ambient temperature, repeat the process by freezing the sensor to its lowest reading, and allowing it to heat up to ambient, and learning the ADC readings as it reaches the appropriate temperatures.

If you have a table or graph that gives the resistance values of the sensor at different temperatures, the ADC value can be manually calculated from this resistance (R). The formula is given below:

Note that this must be performed for all temperature sensors in use (water temperature sensor, air temperature and auxiliary temperature). There is no need to enter values for a sensor which will not be connected.