Why does it do this? its in a very cold room… does that have to do with it? i tried raising default temps of 220c to 235 and that helped a little bit but it still ruins my prints. prints fine in normal mode but as soon as i switched to faster speed it started under extruding and ruining my print
Have you checked to see if the thermal paste on the nozzle hasn’t dried out?
2 Likes
just got this printer… had it less then 2 months maybe. it shouldn’t need it that soon after buying it does it? it prints fine in normal mode but as soon as i switch to sport it start under extruding. i dont even want to try in Ludacris mode 
and then on round circles it makes this weird burring noise. sound nornal on other parts of the print. im worried that it being in this cold part of my house is wairing on it and its gonna fall apart soon
I’m just giving you things to check that others have found to be a problem when trying to print fast.
Another question is what kind of filament are you using? There are kinds that struggle to flow at the higher printing speeds.
2 Likes
I’m using bambu pla basic. could it be a problem that its in a cold room? or a problem with the extruder? It looks like its basically only a problem when it has to output a ton of filament like in 100% infill or the solid layers that come after the first layer
How cold is the room in specs ?
With speeds some filaments do want a higher nozzle temps and you said you moved it to 235c and it got better but you also said the room is very cold. You might have to back the cooling fans down from the 100% value if the room is super cold.
yeah the room is probably like 50-55 degrees F. Its a bbl p1s so it has an enclosure. turning the temps up helped a little but it didn’t help to the point where i could print in sport mode. Its currently 2 degrees F outside that why it’s so cold in an inside room… i’m probably just going to let my printer rest until it warms up outside and the heat can keep up in the printing room.
Ok you are not printing in the Arctic 
Is this the only pla filament doing it ?
What nozzle size and type ?
What Layer Height @
Line width @ defaults ?
What’s your max volumetric speed @
What does the speed show in the preview screen after slicing this part ?
What is your fan setup do you have the Aux fan also
Yep I’m using all the defaults except a little slower on outer walls and @.2 mm layer height and I have the aux fan as it came stock on the p1s. I’m using a .4 mm nozzle and its stock hotend. and my max volumetric flow rate is 21mm3/s. This printer should be capable of printing in sport/Ludacris mode without this bad of under extrusion.
Wow! i was using bambu pla basic so i switched over to black pla matt and that did the trick! it now print almost perfectly in Ludacris mode now! Thanks to everyone that helped me!
Most likely Bambu lab has not tested all the filament colors out.
You can also turn the aux fan off or set it to 30% and see what happens on the next test with the gray pla filament.
Yep each filament will be different even colors can affect the filaments.
Best thing to do is calibrate your filaments with Orca slicer and test your nozzle temps at high speeds don’t use a temp tower for this type of testing.
This is an interesting post. I’ve had my P1S for just a week and today I decided to try Ludacris mode. I printed the cap portion of a model I found that fills the core of a spool which you can weigh down to mitigate bouncing when the filament gets low.
I had ordered some PLA Black Matte with the machine which as you know comes with samples of PLA Orange and Green. Since I have more Black, being a new full spool, that’s what I used and it printed perfectly. So by luck, I used the right material.
I printed at 240C because of the faster flow. It printed really nicely at 0.28mm layer height.
I won’t try printing it on the other PLA Basic colors thanks to your post.
Interesting, so the fix is switching to Matte filament?
I am hitting similar issue trying to do a sub-10min speed 3d benchy. I got the same under extrusion on the deck area of the benchy, and I have to slow down.