I need to build a custom firmware for a Titan extruder

Hi everyone!

I just upgraded my Ender 3 Pro with a E3D V6 hotend and a Titan extruder. I’m having problems with my e-step calculations. I enter G91 → G1 E100 F50 and after extruding, I measure my left over filament. I’m getting 93mm left over, so it seems that I’m not extruding properly. If I accept that value and do the calculations for it, (344.44444), when I rerun G1 E100 F50 to test, I end up with 39mm left over, which is 19mm to much. Just to mention, I rewired my extruder to run in the proper direction for the Titan.

Is this something that I need to tune in Marlin? And if yes, how do I do that?