2.5 TDI after LMM replacement: better, but not yet good.

Hello everyone,
It's only partially true: yes, I signed up here because of the high technical level, but not only. I've never had the chance to work with people who also have a good understanding of cars. No, that's serious. When I tried to explain my impressions to the garage, I quickly realized that they couldn't or wouldn't follow me. My A4 B5 2.5 TDI AKN is my first really good car, and I fell in love with it at first sight. I've had it for 3 weeks, but due to a lack of experience and probably also due to the blinding effect, I'm slowly starting to realize that it's not running as well as it could. And despite its flaws, I always enjoy using the car when I need it.

My previous experience with diesels was an Astra 2.0 with 100 hp (150,000 km) and a few kilometers with a 90 hp Golf TDI. In both vehicles, I found that, for example, when driving at 50 mph in town in 3rd gear, just before the full turbo boost, and then, for example, giving 50-60% of full throttle at the exit of town, one achieved the best acceleration. The same applies when following a truck and preparing to overtake. According to my experience, full throttle would not have been as effective. This also applies to petrol engines, except for the new, double-charged petrol engines from VW. But I'm not so sure about that.

Now, regarding the AKN in my B5. Initially, I thought the 6-cylinder engine simply had a different characteristic, but after repeated testing, it became increasingly clear that the engine briefly indicated the typical diesel pressure at around 2000 RPM, then gradually lost power. I did some research and replaced the MAF sensor. Yes, that already felt better. After driving for a few kilometers on the highway, I could again feel a significant improvement. It was almost as good as I expected. Incidentally, the error memory is empty. Now, it's sometimes better, sometimes worse, and I'm not really satisfied. I get the best acceleration by pressing the accelerator pedal precisely, but this doesn't always work. The old trick of giving it full throttle (50-60%) doesn't really work; too much gas slows down the acceleration. I'm not ready to go to the friendly shop yet, because when I needed help with the faulty 5-star Torx screw, the employee there was actually ready to help me without a request, but then, when he saw that I only had the sensor, he said that it wouldn't work because it had to be exactly in the airflow, and for that I would have to have the whole assembly with the pipe. Now I've removed the screws with a water pump wrench and have discovered that it's absolutely idiot-proof, because you can't adjust it or install it incorrectly. So much for the friendly service. I can already hear what they want to replace it with, which might be a cheaper solution. As for the maximum speed, I can't really say anything about it, because it's too short. The speedometer shows 220 lt, but it's already okay. Oh, it has 140,000 km on it.

Okay, now it's time to wrap it up. I'm a curious beginner. I know some things, but of course not everything. Maybe someone has a valuable tip, based on the information that the full-throttle driving has also brought a significant improvement, in addition to the replacement of the LMM.

Best regards and thank you in advance.

Vidi

[Translating...]

mhh...

so recht weiß ich nun auch noch nicht wo dein motorisches Problem liegt. Zum LMM: Wo hast du den gekauft und wie billig war der? So ein Chinading von ibay? Dann wirst du da nicht lange Freude haben.
Das der 6 Zylinder eine ganz andere Charakteristik hat wie kleine 4 Zylinder ist an sich absolut normal.
Hast du schon hier über den AKN und seine Probleme, die in etwa bei deinem km Stand beginnen, gelesen: Sichwort Nockenwellen?

[Translating...]

Servus,

das war der Peirburg LMM ausm Autoteilehandel für 86 Euros. Ich hoffe doch stark, dass es nicht die NWen sind oder was anderes schweineteures. Das könnte ich mir nicht leisten. Der Wagen ist sonst bestechend leise und ruhig. Es qualmt und ruckelt nix.

[Translating...]

Einen 6 Zylinder fährt man automatisch Untertouriger, so ist es jedenfalls bei mir. Er zieht sauber ab 1600U/min hoch wo ein 4-Zylinder sich noch etwas schüllelt und nicht willig ist. der AFB/AKN sind etwas steifer wie die 4-Zylinder, drehen nicht so schnell hoch. Ich sehe diese motoren eher so als die eines Lieferwagens, nicht so wie in einem Rennauto, dafür geht ihen ber dann die Puste nicht so schnell aus wie bei den 4-Zyinder, er dreht sauber und kraftvoll bis 4500U/min hoch, obwohl er sich dort nicht so wohl fühlt.

Er kann sein das die VTG etwas fest sicht und nicght immer zu 100% richtig funktionniert und nicht den vollen Druck aufbaut, dadurch wird dann weniger Luftmasse erkannt und die Einspritzmenge wird zuückgenommen, das wird sich aber in nächster Zeit dann bei dir zeigen. Das mit der Autobahnfahrt kann ich bestätigen, nach dem Urlaub läuft meiner auch deutilich besser als nach monatelangem Berufsverkehr auf kleinen Strassen...
Das sind meine Erfahrungen.

Bis dann