P2S: PETG Basic first layer over-squishes and blobs. Extruder motor overloaded

[victorcg03]

Setup

• Printer: Bambu Lab P2S with AMS 2 Pro
• Firmware: 01.02.00.00
• Slicer: Bambu Studio 2.6.0.51
• Filament: Bambu PETG Basic (black), stored in AMS 2 Pro, humidity reads 10-17%
• Nozzle: 0.4 hardened steel (stock) — happens with both my old and my brand new nozzle
• Plate: Textured PEI, cleaned with soap and water
• Profile: stock “Bambu PETG Basic”, no modifications
• Temps: stock profile values
• Calibration: full calibration (bed level + flow dynamics) run immediately before printing

Problem

The first layer comes out badly on every PETG print, regardless of part size.
It over-builds material and creates blobs across the surface, which the nozzle
then drags around. I also get recurring “extruder motor overloaded” errors,
sometimes mid-print.

Key observations:

• PLA prints perfectly. This only happens with PETG Basic.
• A Benchy had the same bad first layer, but finished acceptably — except the
  embossed lettering on the underside is completely smeared over and unreadable,
  and the whole bottom surface looks wrong.
• Large flat parts are worse, since there is more first-layer area.
• Sometimes the print still finishes fine despite the bad first layer.
• Same behaviour with the old nozzle and with a brand new one.

The filament is dry — AMS 2 Pro reads 10-17%, and I also dried it for 16+ hours.

Already tried

• Full printer recalibration (bed level + flow dynamics)
• Dried the filament 16+ hours
• Cleaned the plate with soap and water
• Replaced the nozzle with a new one

Photos

Related

I found this thread reporting problems with the new PETG Basic formulation
(which replaces PETG HF), including a user on a P2S:

Is the new PETG Basic bad?

since the PETG HF is no longer being sold i bought some rolls of PETG Basic but ever since i got the rolls, the prints have not been in my favour, strange small missprints in the middle of bigger prints, and specifically the red PETG Basic stuck so strong to my Textured PEI Plate that i had to submerge the entire build plate in Hot water and spend 10 minutes getting the fillament off does anyone else have experience with the new Fillament?

Most of that thread is about excessive plate adhesion rather than my exact
issue, but it raises a question:

Are the stock Bambu Studio PETG Basic profiles tuned for the old PETG HF
formulation? If the new material is stickier and less forgiving, the stock
first layer squish might simply be too aggressive for it.

Questions

1. The lost lettering on the Benchy underside suggests over-squish / over-extrusion
   on the first layer rather than a clog. Does that match what you see in the photos?
2. Is the stock PETG Basic profile on the P2S known to run too much first layer
   squish on textured PEI? What Z-offset and first layer flow values are people using?
3. Is the “extruder motor overloaded” error just backpressure from the squished
   first layer, or should I be worried about the extruder itself? It never happens
   with PLA.
4. Has anyone adjusted the stock PETG Basic profile since the reformulation from PETG HF? Specifically first layer height, flow and Z-offset.

Thanks in advance.

[user_1476463080]

Hello,
Same problem here : PETG basic white on H2S and H2D.
On my side, first layer is OK (bottom layers), but exactly same problem as you in terms of aspects during infill
I am trying to print big parts.
Any solutions here ?