15k Maplin thermistor test results
From my tests it looks like a simple 15K Maplin thermistor is a possibility, at least if you ride between 0c (freezing) and 25c, but it certainly doesn’t give a nice flat temperature response as the BoosterPlug or Accelerator module should. Beyond 25c fuelling may become a little too rich, but without trying it , its hard to say. It’s certainly a whole lot better than a simple resistor in place of the IAT sensor, and lots of people are riding around with one of them.
One bodge DIY option to extend the usable temperature range of the 15k thermistor maybe to add a series resistor you can switch out for those days when the temperature gets close to 25c or over, sort of a high/low setting if you like.
Interpretation of the figures:
If fueling is increased/decreased by 3% for every 10c temperature change…
At an ambient 0c It just fell short of 6% extra fuel with 18c setback, 5.4% extra fuel
At an ambient 8c I had 20c setback equaling an ideal? 6% extra fuel
At an ambient 15c I had 22.5c setback giving 6.75%
At an ambient 20c I had 23c setback giving 7% extra fuel
At an ambient 25c I had 25c setback giving 7.5% extra fuel
At an ambient 30c I had 26.2c setback giving 9% extra fuel
Really, what your hoping for is a nice even 20c all the way down the last column labeled 'Setback' to give you 6% extra fuel.