u/Ioauis

When I try to print in PETG specifically most of the time I see it start well and then increase above the set temperature of 240 and then rapidly cool down to 170 then back up then down till it rings out nozzle temperature too low or very rarely too high. There is also brown PETG residue on the print and i have to run to it so it does not burn something from it stopping and creating a blob making the problem worse. While this was happening on only PETG printing it just now happened when extruding and am stumped. I have no idea what am doing wrong. Can anyone help? For extra context I have tried printing at 225 but it went up to 240 dropped and did the whole thing again. Also sometimes it just does not happen for no particular reason. Furthermore it only seems to happen on PETG. I use orcaslicer with the built in ender-3 v3 se profile and the filament settings adjusted to my Creality hyper PETG white.