Hi Pieter
To answer your question we need to first identify what you are talking about.
The Madman EGT system uses a thermocouple as temperature probe.
What is a thermocouple? A thermocouple is a temperature sensor that measures temperature by generating a small voltage signal proportional to the temperature difference between the junctions of two dissimilar metals. One junction (the hot junction) is typically encased in a sensor probe at the point of measurement; the other junction (the cold junction) is connected to the measuring instrument. The measurement instrument measures the voltage signal and the cold junction temperature then computes the temperature. (
http://www.heatonc.com)
Your question regarding the type of probe refers to its sensitivity.
Type K
Chromel ( Nickel-Chromium Alloy ) / Alumel ( Nickel-Aluminium Alloy )
This is the most commomly used "general purpose" thermocouples. They are available in the ~
-200 °C to +1200 °C range. The characteristic of the thermocouple undergoes a step change when a magnetic material reaches its Curie point. This occurs for this thermocouple at ~ 352°C. Sensitivity is ~ 41 µV/°C.
Type J
Iron / Constantan
Limited range (~ -40 to +750 °C) makes type J less popular than type K. The main application is with old equipment that cannot accept modern thermocouples. J types cannot be used above 760 °C as an abrupt magnetic transformation causes permanent decalibration. The magnetic properties also prevent use in some applications. Type J's have a sensitivity of ~ 53µV/°C.
So, Yes, which setting you select will have an impact, particularly as the type J has a max reading capability of 750°C. If your engine works really hard, this reading can be exceeded and as stated will cause permanent damage to the probe. Make sure you have fitted a type K and that the EMS is set to read type K ranges.
Hope this helps