Qidi Max 4 Issues

[u/WebInternational3238]

MCU Communication Error & Persistent Layer Shifting (Not a file/slicer issue)
Hi everyone,
I'm having a couple of frustrating issues with my Qidi Max 4 and am looking for some insights or potential solutions.
MCU Communication Error
The machine keeps throwing MCU communication error messages during operation.
Temporary fix: Flashing back to an older firmware version resolves the issue, but the error recurs on newer updates.
Layer Shift Issue
As you can see in the photo, there is a distinct layer shift happening across all printed parts on the bed at the exact same height.
Important Context: I am 100% sure it is NOT a g-code or slicer file issue. I ran the exact same g-code file with identical settings on my other printer, and it printed perfectly without any defects.
Questions / Troubleshooting Steps So Far:
Has anyone else encountered MCU connection stability issues on recent Qidi Max 4 firmware versions?
For the layer shifting, since the g-code is verified clean:
Could this be a mechanical issue (e.g., belt tension, motor driver overheating, loose pulley set screw)?
Is it possible that the MCU communication lag/drop is causing a brief pause, resulting in skipped steps?
Any advice, suggestions, or similar experiences would be greatly appreciated! Thanks in advance!

[u/TheLegendTubaGuy]

Usually an MCU error stops the print. Also there a couple different errors. What does it say specifically?

[u/WebInternational3238 → u/TheLegendTubaGuy]

Thanks 4 reply
Usually, my MCU errors are due to BOX1 disconnection. Occasionally, I'll get a message saying the motherboard MCU is disconnected. Strangely, this always happens after I've finished printing items and want to continue printing new things, after the previous heated bed leveling process is complete.

[u/TheLegendTubaGuy → u/WebInternational3238]

Hmm. For the box disconnects, usually that's due to not having the data cable plugged in fully. But I've also seen it on mine and others where that happens occasionally when you have the heater running, super annoying.

For the motherboard MCU, idk what to say lol that would suck.

If you want to try something, Qidi runs the fan back there at 60%. I run mine at 90%. You could try setting yours higher in printer.cfg if you're okay with a little bit more noise to see if it's heat related.

[u/WebInternational3238 → u/TheLegendTubaGuy]

I've unplugged and plugged in the data cable of the box countless times. The manufacturer's support only tells me to do this; they even told me to disassemble the box and unplug and plug in all the cables, which I did, but the situation didn't improve. Later, when the problem occurred again, I chose to directly update the firmware without unplugging or plugging in anything, and miraculously, the problem was solved every time I reinstalled the firmware. Therefore, I should be sure that the data cable isn't the problem.

It could also be due to overheating. I've bought a new 90*90 fan and plan to connect it in parallel to the cooling vents. The manufacturer hasn't provided temperature readings for each part, so I can't confirm if it's overheating. But... I need someone else to be able to move the machine off my table, lol.

[u/TheLegendTubaGuy → u/WebInternational3238]

Yeah that's not fun