Although my CuraEngine's interface is into Repetier-host (not as independent window) with one solely place to change temperatures (Filament tab) and I had changed this setting to 90º and 230º, actually the temperatures the printer went to were 50 and 210 (as seen in Manual Control panel).

My error was that in the tab Slicer of Repetier-host, previous to push the button "Slice with CuraEngine" I didn't change to the new settings through the options  "Print Configuration" and "Extruder 1". So the settings sent to the printer were the default ones and not those changed by me.

Uff, I'm not sure about my explanations are clear to you. But I try!!

Anyway, solved with your help that made me search and search through all the possible options.

Thanks a lot.

Most likely source of your temps change. This is the slicer settings and they override all other settings.

I've changed them in Cura configuration (Filament tab), but I'have started another little printing and another time the heating levels were 50 and 210. Then I interrupted the printing, closed Repetier-host and newly opened it. I sent another printing and another time the temperature levels had been 50 and 210, so printing right now manually forcing to 90 and 230.

Although I'm confident that this finding of temperature settings in Cura could be the begin for the solution.

What is your Cura settings?

Which ones? I didn't see anything in CuraEngine about temperature of bed or extrusor. As I know, just in Printer Properties and in Manual Control of Repetier-host there are adjusts for both temperatures.

I have to manually set the initial heating to 90º and 230º and when the printing starts (when the head is moving itself) another time I have to force manually those levels (if I don't do this, the printing is autoadjusted to 50º and 210º and the temperatures start going down).

Is it right? Should I change? How can I change?