Golf smoking? Get help now!

Okay, I had a chip installed in my Golf TDI 81kw AFN about half a year ago, but the problem is that it starts to produce black smoke whenever I fully depress the accelerator pedal. However, when I only use about 3/4 of the accelerator, I would say everything seems normal. I've done some reading in the forum and even disconnected my EGR valve, but it didn't help. Thanks in advance for your replies.

Hi.

Are you sure it wasn't already producing soot from the tuning process, and that you simply didn't notice it before?
This is crucial because it significantly impacts the next steps.
"Black smoke" caused by chip tuning is, in my opinion, not likely – black smoke due to consequential damage from excessive tuning is more probable (e.g., piston melting, etc.).

Given that the EDC normally "carefully" prevents excessive soot production (unless it's been caused by a modification, but in that case, it should have started producing soot immediately after the modification), the most likely cause, in my opinion, is either a stuck-open EGR valve (which can sometimes "remain" stuck even after disconnecting the EGR hose / see the EGR technical article), or a leak between the turbocharger outlet and the intake valves, where air is being lost.
The latter usually reveals itself through oil leakage that runs down the outside of the leak. Unfortunately, it can also occur in hidden areas (like the LLK, etc.), so happy hunting!

I also think it's conceivable that, in an exceptional case, a LMM (likely referring to a measurement device) could produce readings that are unusually high.

Hello!

The simplest possibility is a completely clogged air filter.
I just mean it like that.
Sometimes you can't see the forest for the trees.

Hi D.

'Mine doesn't have a map for air temperature. It's still the old reliable model. But it's possible that the tuning chip's map isn't steep enough, and that it's still letting in too much air given the currently high temperatures. That's why it wasn't happening at first. It was cold outside.'
Or is it only the LMM (lambda measuring module) that does it? Oops, I probably don't understand enough about how your system works. If it's in the LMM, then my concerns are unfounded. If it's in the control unit, then the tuner might have messed something up.