Loud humming noise when accelerating

Hello everyone,
I have an Audi A4 B7 Avant 2.0 TDI 8V with the BPW engine. I just finished a major repair, including having the DPF cleaned, a new (original Garrett) turbocharger installed, all the PDE injectors checked, a new tandem pump, and a new cylinder head with all related components (only the rocker arms are the old ones). I feel like the engine is running rougher than before.
My problem is somewhat similar to the issue where the sealing plugs in the tilting lever shaft are missing (although I checked today and they are definitely there).
"This weekend, I drove almost 1000 km, and occasionally, during acceleration between 1500-2500 RPM, it sounded like a gasoline engine with an open air filter, similar to what was described in the thread where the plugs are missing."
I'm running out of ideas and hope you can help me.
Could it be that a DPF cleaning cycle has already taken place? I haven't really noticed when the car has performed one before.

You can use VCDS to read the measurement data and see when the last DPF cleaning cycle occurred. This allows you to determine whether that cleaning cycle coincided with the time you noticed the change, or if it was unrelated. However, keep in mind that the regeneration process typically occurs approximately every 400 km, depending on driving style and engine type. This means that over 1,000 km, you would have had multiple regeneration cycles. Therefore, if the rumbling noise was noticed at the beginning of a trip, you may not be able to determine if it was related to a regeneration cycle.

As long as your driving style and route remain similar, you can now wait for the last regeneration and the next two regenerations and then calculate backwards. With my Passat from 2008, I could generally rely on a range of 350-400 km between regenerations when driving long distances.

guste100 wrote:

You can read the last DPF cleaning date from the measurement data using VCDS. This allows you to determine whether it occurred at the time of the perceived change or independently of it. However, keep in mind that the regeneration process typically occurs approximately every 400 km, depending on driving style and engine. This means that over 1,000 km, you would have had several regenerations. Therefore, if the humming was noticed at the beginning of the journey, you can no longer determine whether it was due to the regeneration process. As long as the driving style and route remain comparable, you can now also wait for the last regeneration and the next two regenerations and then calculate backwards. With my Passat from 2008, you could generally rely on approximately 350-400 km between regenerations when driving long distances.

Thank you for the quick response. I'm just concerned about where this noise might be coming from.

Tobias74 wrote:

Thank you for the quick response; I'm just concerned about where this noise might be coming from

.
Then try to reproduce the issue and connect VCDS. You can then check the relevant control module data (in VCDS) to see if the regeneration process is running, or if you need to look for the problem elsewhere.

My crystal ball is currently indicating a DPF regeneration is needed, but the information is quite vague. At least an audio file would be helpful to get a clearer picture.

Regards,
Guste.

"I'll try reading it tomorrow, but I'm not using it right now. We only have a Gutmann tester here, so let's see what it says. Unfortunately, where I had a total failure, there are no error codes. However, all the failures were mechanical – the PDE was faulty, and the camshaft was almost completely worn. But I can see with the tester when the last regeneration cycle was."

Okay, the error memory is clear, the last regeneration was 140 km ago, so it's possible that was a cleaning cycle. The post-injection adjustment for the common rail pressure sensor is between -0.3 and +0.3 (idle speed regulation), which should ideally be optimal.

I'm a bit unsure because I've just completely overhauled everything, and it seems to be running a bit rougher than before.