A6 C5 2.5 V6 TDI: No Power Above 3000 RPM

Hello!

I've been trying the search function for a while now, and I've found some threads, but none of them have really helped me yet...

Yesterday, I looked at a used Audi A6 2.5 TDI quattro with Tiptronic transmission, manufactured in 1999, with 240,000 kilometers on the odometer. The car has a complete service history and appears to be well-maintained overall.

The problem: The engine runs somewhat normally at low speeds, but above 3000 RPM, it struggles significantly and has very little power.
When I rev it up in neutral, it initially revs well, but something still isn't right. It seems like it hesitates somewhere between 3500 and 4000 RPM, then it revs up to the limiter. When it exceeds this "threshold" in neutral, you can hear a "PFFFT" sound from the front, as if the VTG adjustment system has done something.

The error code stored was: "Intake manifold pressure exceeds regulation limit." After clearing the error, there was no improvement, but it did not reappear after a 2km test drive.

I also performed the actuator diagnosis, and in my opinion, the VTG (Variable Turbine Geometry) adjustment seems to be working quite well.

Furthermore, a friend of mine performed a VAG-COM log and recorded channels 10 and 11. I can gladly post the log tomorrow. From what I could see, the boost pressure was mostly quite consistent, and the maximum boost pressure was around 2.1 bar, if I remember correctly.

Maybe someone here has an idea; I have to decide on Monday whether or not to buy the Audi.

Best regards and thank you from Vienna.
ingo

I have been trying the search function for quite some time now, and I have also found some threads, but it hasn't really helped me yet...}

Hi.
Please try the search function again, and include the following ICD codes: AFB and AKN.

Best regards from Hamburg, Kurt.

Keyword for search: camshafts

vwSchrauber wrote:

Keyword for search: camshafts

I highly doubt that. It's more likely to be the turbocharger, or a clogged exhaust system, or something like that. Even with 4 broken camshafts, these engines still run pretty well.