Vibrations / Rumbling in a specific RPM range for 2.0 TDI

Hello,

The engine of my A3 Sportback 8P 2.0 TDI (125 kW) has been vibrating in the 1,400 RPM (1200-1600) range for some time.
Does the engine not have any balance shafts or something that could be changing?
It's not just a noticeable humming sound, but actually a noticeable vibration.

What probably doesn't have anything to do with it, but I still want to mention:

Sometimes (!) after being parked for several hours, the engine doesn't start / or starts very poorly and initially runs extremely rough, as if on 3 cylinders. Normally, it starts perfectly... No fault was found...

This summer, as part of an Audi campaign, the pump-nozzle elements were replaced.
After that, I noticed a high oil consumption (the first time I had experienced this with several TDI's I had owned), almost 1 liter per 10,000 km!
Mileage is approximately 60,000 km

Who has tips or suggestions on where these vibrations might be coming from?

And one more question: I haven't been able to find another forum:
The coolant level indicator has been flashing frequently lately, even though sufficient coolant has been added.
Are there specified acceptable values for the sensor, or how can I determine if the problem is actually with the sensor and not, for example, due to a poor connection in the wiring?

Thank you!
Erka

It sounds like there's air in the system when it won't start. In combination with the rough engine running, it's likely that one of the PDs is leaking.

The values from the idle control system would now be interesting. Perhaps something could be derived from there.

Thanks in advance.

It's strange, though, that it usually starts up perfectly and runs smoothly at higher speeds. The idle is also fine.

However, around 1400 rpm – regardless of whether the engine is cold or warm – this happens...

Ah, and one more thing: Even when I take my foot off the gas, and the engine smoothly transitions from a higher RPM to a lower one, this happens briefly.

Does that mean it can't be related to the PDs?

Best regards,
Erka

Zitat:

That basically means there's nothing to do with the PDs, right?

That's speculation... we'd need to do a diagnostic scan and the values described above:idea:

... or we could just ask the crystal ball:wink:

I think I should probably take it to the workshop...

Thanks in advance and Merry Christmas to everyone

hm, now the yellow warning light for the exhaust system is on constantly...
(not the particulate filter)

Does anyone have a tip for a good garage in the southern/southwestern part of Munich?
(I paid almost 200 EUR last time just for them to find nothing...)

Greetings
Erka

Zitat:

(I already paid almost 200 EUR last time because they couldn't find anything...)

...that would have already paid for itself in half