Makerfarm Prusa I3V nozzle temp issue...

[printbus]

I'd include info on exactly what you're using for firmware. Are you using a MakerFarm baseline or a newer version from the Marlin github?

EDIT: One of your other threads says the setpoint inexplicably changes away from the initial 215. Is that true? If so, post a copy of a gcode file where that happens to pastebin, dropbox, or somewhere so we can look at it to confirm there's nothing in the gcode to explain it.

If the setpoint isn't inexplicably changing, don't rule out a hardware problem...

Is the heater clamped tight in the hot end? If it is loose it can't heat the hot end properly. Or maybe the hot end heater is failing.

How securely is the thermistor attached to the hot end? If it is a bit loose, the thermistor will likely read a lower temperature than actual. Depending on how bad the thermal connection is, the hot end could appear to never reach temperature when it is actually running way over temperature.

How are the wires from the hot end heater and thermistor bundled and routed? Are they tied in any way that keeps the wires from shifting at the heater and thermistor as the x-carriage raises up during a print? Wires tugging on the hot end would aggravate issues with a loose heater or thermistor.

How much faith do you have in your power supply? Printing with the heated bed is going to put a hefty load on the power supply. Have you measured the power supply voltage during a print or at least when you're having the hot end temperature issue to make sure it is still outputting what it should? I seem to recall a thread from a few months ago where the power supply died while we were troubleshooting a similar setpoint issue with either the hot end or the heated bed.