I Need Help With Multi Material Printing

[spegelius]

OK I loaded a 5 color multi material test print into prusa slicer and sliced it. Here is that Gcode. Can you please compare this to your start gcode and tell me what i am doing wrong?

To my understanding, everything should be ok. This print doesn't seem to have the filament priming feature enabled, it just loads the first filament and starts to print. Have you tried printing it yet?

Here's the initial start gcode, standard stuff. Add mesh bed leveling command if you need to:

M73 P0 R137 ; progress indication
M107 ; fan off
G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S240 ; set extruder temp
M140 S60 ; set bed temp
M190 S60 ; wait for bed temp
M109 S240 ; wait for extruder temp
G28  ; home all without mesh bed level

This sets up MMU2S so that it knows what type of filament is loaded

; Send the filament type to the MMU2.0 unit.
; E stands for extruder number, F stands for filament type (0: default; 1:flex; 2: PVA)
M403 E0 F0
M403 E1 F0
M403 E2 F0
M403 E3 F0
M403 E4 F0

This part loads first filament to nozzle. The initial load length seems low, for me it does more than double that. That could be the problem, it's just no feeding the filament far enough initially.

;go outside print area
G1 Y0.0 F1000.0
G1 X260 F1000.0
G1 Z0.2 F1000.0
; select extruder
T0
; initial load
G1 E29.0 F1073.0
M73 P0 R137
G92 E0.0

For some reason does another loading of first filament, not sure if this actually does anything because the filament is already loaded. Don't know why this is here, but I have it too so apparently it's needed or just redundant stuff that Prusa team hasn't cleaned away.

G92 E0.0
G21 ; set units to millimeters
G90 ; use absolute coordinates
M83 ; use relative distances for extrusion
T0
; Filament gcode
G1 Z0.500 F4800.000
;BEFORE_LAYER_CHANGE
G92 E0.0
;0.3

Moves to purge tower position

G1 E-1.00000 F2100.00000
G1 Z1.100 F4800.000
G1 Z0.500
;AFTER_LAYER_CHANGE
;0.3
G1 E-2.00000 F2100.00000
G1 Z1.100 F4800.000
G1 X101.016 Y209.785
G1 Z0.500
G1 E3.00000 F2100.00000
;-------------------------------------
; CP WIPE TOWER FIRST LAYER BRIM START

So the initial load part seems to be the only problematic section.

I suggest you check the Printer Settings -> Single extruder MM setup section, this is what I have:
SingleMMSettings.jpg

Edit: actually the initial load section seems to be in the Start gcode-section, this is what I have in there:

M862.3 P "[printer_model]" ; printer model check
M862.1 P[nozzle_diameter] ; nozzle diameter check
M115 U3.9.0 ; tell printer latest fw version
G90 ; use absolute coordinates
M83 ; extruder relative mode
M104 S[first_layer_temperature] ; set extruder temp
M140 S[first_layer_bed_temperature] ; set bed temp
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S[first_layer_temperature] ; wait for extruder temp
G28 W ; home all without mesh bed level
G80 ; mesh bed leveling

; Send the filament type to the MMU2.0 unit.
; E stands for extruder number, F stands for filament type (0: default; 1:flex; 2: PVA)
M403 E0 F{"" + ((filament_type[0]=="FLEX") ? 1 : ((filament_type[0]=="PVA") ? 2 : 0))}
M403 E1 F{"" + ((filament_type[1]=="FLEX") ? 1 : ((filament_type[1]=="PVA") ? 2 : 0))}
M403 E2 F{"" + ((filament_type[2]=="FLEX") ? 1 : ((filament_type[2]=="PVA") ? 2 : 0))}
M403 E3 F{"" + ((filament_type[3]=="FLEX") ? 1 : ((filament_type[3]=="PVA") ? 2 : 0))}
M403 E4 F{"" + ((filament_type[4]=="FLEX") ? 1 : ((filament_type[4]=="PVA") ? 2 : 0))}

{if not has_single_extruder_multi_material_priming}
;go outside print area
G1 Y-3.0 F1000.0
G1 Z0.4 F1000.0
; select extruder
T[initial_tool]
; initial load
G1 X55.0 E29.0 F1073.0
G1 X5.0 E29.0 F1800.0
G1 X55.0 E8.0 F2000.0
G1 Z0.3 F1000.0
G92 E0.0
G1 X240.0 E25.0 F2200.0
G1 Y-2.0 F1000.0
G1 X55.0 E25 F1400.0
G1 Z0.20 F1000.0
G1 X5.0 E4.0 F1000.0
G92 E0.0
{endif}
G92 E0.0

Try copying the lines after ;initial load to your start gcode