<font face="Arial, Verdana">When I configure repetier firmware to use a 3-way mixing extruder, it will default to use all three extruders equially, and print with all three, no matter what extruder I chose to use.</font>
To fix it, I have to configure mixing for T0-2 in the beginning of my code:
<font face="Arial, Verdana">M163 S0 P100</font>
<font face="Arial, Verdana">M163 S1 P0</font>
<font face="Arial, Verdana">M163 S2 P0</font>
M164 S0
<font face="Arial, Verdana">M163 S0 P0</font>
<font face="Arial, Verdana">M163 S1 P100</font>
<font face="Arial, Verdana">M163 S2 P0</font>
M164 S1
<font face="Arial, Verdana">M163 S0 P0</font>
<font face="Arial, Verdana">M163 S1 P0</font>
<font face="Arial, Verdana">M163 S2 P100</font>
M164 S2
I guess the default for all 16 virtual extruders needs to be proberly configured.