Inconsistent hotend temp, Auto PID failure

[Armatus]

So I just got a Rostock Max v2 and right away upgraded the hotend to one of the Hexagon models, as most of my prints are in PETG and need to be at 260*. It's giving me a weird issue though, I'll tell it to heat up to 255* and it will reach that temp just fine, but it won't hold it accurately, it constantly fluctuates 3-5 degrees regardless of whether or not it's printing, which is quite a lot. This is without any of the exterior cooling fans running. I've tried PID tuning several times with the code M303 S255 and it starts just fine and runs through a few cycles, but then it just stops without giving me any finishing values. I'm at a loss here, any help?

[IMBoring25]

It should be outputting lines of information to the gcode console in your host software the entire time it's doing the autotune. Is it not?

[Xenocrates]

What do you mean by finishing values? The printer gives you 3 sets to average together yourself, rather than doing it for you. If those don't suit, I would work on manually tuning your PID. Likely decreasing your I value is what you need. Manual tuning, while sometimes tedious, will be better than an autotune in almost any case. See here: https://www.instrumart.com/pages/202/ma ... controller

That being said, what is your reasoning behind the Hexagon hotend, rather than a better known one like the E3D V6 or Prometheus?

[Armatus]

It is outputting lines the entire time, yes. I got it to complete a full tune finally by starting at 205 and inputting those values, then 225, 245 and finally 255. I still have the same problem though.
The Hexagon was ~$50 and the reviews on it were in line with those of the E3D, and being that the Hexagon is so much cheaper I naturally purchased it.