Which preset are you using? 0.20mm Standard?
If I were you, I would try to increase temperatures a bit - try +10°C on bed and nozzle. Then set First layer speed really slow - like 20mm/s or so - to see if it gets better or worse. And: Level your bed if you haven’t done it for a while.
Good luck & report back if you like!
Forgot: Best try this with a standard 20mm cube or so, not with your actual model.
Thanks again, I so appreciate all your help. I tried to lower the speed to 20mm/s for the initial layer, and I’m also running the bed at 80. I printed a calibration cube (one of the more “complex ones”, and it came out ok. I actually skipped the flow calibration part, since I don’t think my settings makes any impact on that (might be completely wrong about that though). The cube came out ok. Dimensionally it is very good on all sides (almost exactly 20 mm measured with a caliper), but there are “holes” in the surfaces. I tried to add some images to this reply, but I don’t think I was allowed (new to this forum, so I’m not sure how to add them).
Fine, you are one step further down the road to a good print! You can leave the flow calibraton part unchecked for now, because it is only calibrating dynamic flow (aka pressure advance or k-factor) - this only affects the 4 edges of your cube. K-factor too high: Edges too round, not sharp. Factor too low: too much material at the edges, they are bigger than the cube itself.
Just to be sure: You are not running the beta version of studio software or printer firmware, are you?
Without pictures it is not that easy to help, but maybe you are allowed when your account is 24h old. I don’t know…
That said, I think what you are seeing is gaps in the walls. One possible reason for gaps is “underextrusion”. Later you can learn to calibrate that, but for now you could just edit your filament profile and change flow value from 0.95 to 1.05, slice again and print. If the gaps are gone, you have to calibrate the flow (the static flow, to be exactly). If not, the problem is elsewhere (nozzle temperature, cooling, …)
Excellent info! I tried to step up the temps as suggested but it was just marginally better. I suspected that the filament was just bad. It was a completely new roll of filament from Bambulab (PETG Basic), so there should be no issues. But today I had the opportunity to borrow a roll of Prusament (Prusa PETG, Jet Black). Loaded it, used the Generic PETG profile (changed the temps to 255 nozzle, 85 bed), and just printed with the standard profile and speeds. And it came out almost flawless. No gluestick, on the Engineering Plate. I have since printed a few more models with it and it just works.
So to conclude. My roll of filament must be bad. Perhaps I should try to dry it. But tomorrow I will receive shipment of more filament, among them a few more rolls of the same filament that is not printing, so it will be very interesting to see how it performs. I will have to return the bad roll. Once again, so thankful for all your help, it really educated me on a lot of stuff. And now I also realize that i stole this thread, so sorry for that to the TS.
I will report back to you in a PM (if you like).
This info will help others, as there are a lot of threads about problems with the Bambu Basic PETG on the board. I am curious about your results with the next rolls of filamen!
At the moment, I would argue that the Bambu PETG is not the first choice for Bambu printers. Extrudr, Hatchbox, Prusament, Sunlu etc. seem to work better - and sometimes faster than the original, which should be an advantage of Bambu filaments!
I agree, and I will report back once I have received and tried the new rolls. They will arrive any moment now.
Ok. More info. I have now received another roll of Bambu PETG Basic (Black). I have printed several models now, with all stock settings. And it came out perfect. Engineering plate, no glue. Also printed on the Dual Sided Textured PEI plate. Also perfect (without glue). So, all my troubles were coming from that filament roll (that was brand new, out of the box). I have now put that roll in a filament dryer to try it out. I’m almost certain now it was just damp filament. Sorry to have taken up your time and effort with such a noob mistake. But on the plus side, I learned a lot from it. Hopefully it will have some one else here.
I totally agree. I‘ve printed some PETG filaments from Sunlu, Extrudr and a local supplier (very cheap) and never had any problems. But also with these, my textured PEI plate loose some very small parts of the PEI coating. But I have also some cheap plates from Aliexpress, which works with out any problems. 
I printed also some stuff with the Bambu PLA matte, which was delivered with the printer. But any other PLA filament I‘ve used until now has better print quality than the Bambu PLA, even without calibration. Normally I do the Pressure Advanced and flow calibration and a temp tower with each filament. As with all what I’ve read for me it seems, that the Bambu filament has a quality problem in general. 
I have printed with 4 different Bambu Labs PETG Basic with the default profile and have printed at various speeds and had no real issues. Bambu Labs high temp plate with glue stick, Bambu Labs dual-sided textured PEI with no glue stick. A note I did dry each roll for 12 hours at 65C before loading in the AMS.
Since you’re having great success with your method, may I inquire as to exactly which filament dryer you are using? I’ve been looking into it, and there seems to be a wide range of quality, so if yours is working great for PETG, I’d be very appreciative to know which one.
I am using the Sunlu S2 dryer. I am sure there are far better ones out there but for an entry level unit it works very well, or at least this one does for me.
I tried printing PETG on the cold side of my engineering plate (no glue stick). That’s destroyed now. Adhesion was stronger than the plates glue.
Now I’m back to the hot side. It requires glue stick (otherwise adhesion is only suitable for very slow first layers)
Don’t feel bad. Sooner or later everybody makes that mistake (though usually PETG and a PEI plate), if not on this printer than on some other. I’ve even seen “know it all” youtubers make that mistake on camera. If you look in the bambu lab store under the filament, it will tell you if it advises glue stick or Bambu glue as a release agent for a particular build plate and filament combo.
Just adding my 0.02 cents, I’m an anti-glue stick person, (I have the liquid glue but only will use for exotics.) the textured is good, but my favorite is garolite, namely Lightyear G10 for Bambu. The caveat is you need to set the build plate temp in the filament settings to +10°C whatever its temp is. I usually add +12 for the first layer. I have had 100% perfect PETG prints on garolite once I read the FAQ when I first bought it about adding ten degrees lol.
I honestly hope Bambu sells their own garolite plate.
Me too! Garolite is the best. Worth knowing though: unfortunately, my white Lightyear develops big bubbles in it when heated up, rendering it no longer flat. At least a few others on the forum have reported the same or similar with their Lightyear. My black Lightyear has had no issues.
oh no! I wonder if LIghtyear will cover it under warranty? I’ve been lucky so far with no bubbles, but I’m wondering if the white is cursed and I should get a black :o
