Got lazy but have posted once about my Extruder being the reason why Octoprint or Firmware is not starting the Print.
I compiled my Marlin Firmware by adding
#define DEFAULT_Kp 16.44
#define DEFAULT_Ki 1.58
#define DEFAULT_Kd 42.75
and it starts, but it does weirdly extrude. When I hit "Extrude 5mm" Manually while nothing is running then it seems like a nice constant flow, but when Printing it somehow stocks, retracts or smth when trying to print. At first I thought its TPU and a new abstract material I have never touched but this currently is the good old Black PLA from Creality that I always used.
I use Cura and just used the default settings for PLA like always.
If the only thing you wanted to do is change the PID values then you should go back to your previous firmware. For PID tuning I can recommend this site: https://teachingtechyt.github.io/calibration.html#pid
I heard that compiling your own Marlin Firmware would be better because you get the new features and etc. The Marin firmware gives me my Ender 3 Pro as a config I can compile which I used. So I assume I get nothing in return for using the Official one or my own compiled one.
I learned now that I could save things to eeprom with "M500" command and found on Reddit a post that gave me "M92 E420.69" for my Creality Pro Extruder. A funny number indeed
You can compile a new Marlin for new features but you should know what you are doing and which features you need/want. I have compiled the newes version for myself but I did that because I needed some custom options because I modified the printer.
E420.69 is just a placeholder. For my Ender 3 pro it is around 99. Default is 93.
I still feel like something is wrong because the print looks rough. I measured the length and calibrated it to E427.09 and now it looks like the gaps are filled better but still, the side wall is not sticking to the print at one side. I wanted to print a long sheet as bookmark for context. I guess I create a new post later.
You'll need to determine that extruder value yourself by marking out 70mm of filament from the top of the nozzle and then slowly extruding out 50mm of filament. You should have 20mm remaining after (measuring all this with digital calipers). If you have more than 20mm, you're underextruding and less means over extrusion. To determine your new extrusion value, multiply your current extrusion value by (actual extruded amount/requested extruded amount). For example if you have 30mm leftover, it'd be 420.69 * (40mm/50mm) = 336.552