I have a Wanhao i3+ with an original BLTouch. I also experienced extruder problems after upgrading from 3.x to 4.0.3.
Heat creep is not a plausible cause in my case. Cause the problem comes right away. No time for creep anywhere. And the problem started right after flashing to version 4.
The first problem I saw was that the LCD didn’t always respond as expected. E.g. when asking it to extrude it sometimes started slowly descending the z while the x axis slowly glided toward the right. But only some times. I suspected this could be because a loose cable some where, but I could not find anything wrong anywhere.
When trying to print, I got serious extrusion problems. First I thought it was something to do with cura f-ing up. It looked like coasting was turned on, since the filament always ‘ran out’ before direction shifts. But when trying to print already sliced models from earlier, the printer struggled with that as well.
Anyway - after a lot of grief and trying this and that, I flashed the printer with it’s original firmware last night. The next print (still a pre-sliced model) came out perfectly without any problem.
It’s hard to conclude that this is not caused by something in the 4.x firmware. I know it works perfectly for a lot of people, but if I’ve learned something from 25 years as a software developer, that doesn’t rule out a bug : The (potential) bug might just be more obscure and harder to find… …only shows up if the printer is in a room with a given temperature above the arctic circle if the motherboard was flashed on a Wednesday night…
Software is hard. I really appreciate you effort.
ADVi3++ is a huge improvement over stock firmware, so I’ll definitely try to flash again.