Audi A4 B5 1.8T - 17964

Hello everyone.

Can anyone make sense of this log and possibly tell me where the error lies?

MKB APU, N75, SUV, LMM, etc. are new, but there's a recurring loss of power, especially at high temperatures... today it's 28°C.

Thank you very much.

Evening.

Is the wastegate mechanically okay?
Check the charge air cooler system for leaks and seal any leaks found.

I also think so, and I dimly recall that we once had a shipment of such an engine where the wastegate had fallen apart.

Best regards, Rainer.

The wastegate should be fine. The problem usually occurs when the engine is hot. No leaks were detected, and it was airtight during the last pressure test.

The performance is there... the colder it is, the better... but when it gets hotter, suddenly there's no performance, and an error code appears in the memory.

Okay, then everything seems to be in perfect order. You're quite confident, considering that the boost pressure is too low in all four logs included in the file... Your car is probably not broken; the consistently low actual charging pressure is likely just your imagination.

Yes, exactly... Why is the boost pressure too low? He wants 1.2 bar, but he can't achieve it.

I can only say what has been checked, and everything was found to be in order!

A4CabCH wrote:

The wastegate should be okay.

Unfortunately, this is not a real diagnosis; it should be checked .
It's not uncommon for this engine to experience a broken wastegate rod or for the valve to not always close properly.
When was the intercooler system bled, and more importantly, how?
Is the vehicle chipped?

I would like to emphasize that you should read it carefully, as you haven't been with us for very long yet.
Many people here sacrifice their free time to help others/you .

Okay, I'm ready. Please provide the German text you want me to translate.

A4CabCH wrote:

Why is the boost pressure too low? He wants 1.2 bar, but he can't achieve it.

Are you serious?
If the ACTUAL is below the TARGET , what does that probably mean?!

Off-Topic: Perhaps A4CabCH has the same illness as Merkel.
I'll just say no more now, except to recommend taking note of reality and, preferably, checking the things already mentioned yourself.

Sorry guys, I'm not mechanically inclined, and every time I have to pay a lot of money just to have it checked. That's why I got VCDS so I could narrow it down myself!

I would have expected a little understanding of my lack of knowledge in the field of engines. After all, I'm here to learn. But the wastegate valve, hoses, SUV (likely referring to a specific part), and N75 valve were just checked and confirmed to be in good condition by an Audi enthusiast (a trained mechanic and RS specialist)!

I can understand making jokes, but I find it quite inappropriate right now. I would have preferred a more polite and respectful tone. But since VCDS is already paid for, then there's no need to be nice anymore.

I'm always up for a bit of fun, but unfortunately, I can't really explain the error any further.

"Supplement: Chip tuning applied. Last time checked in the spring (approximately 2500 km ago). A faulty hose was found then, and since then, the boost pressure limit has not been exceeded. Now, with the hot weather, the boost pressure is falling below the expected level."

TDI-GTI-4-Motion wrote:

A4CabCH wrote: Why is the boost pressure too low? He wants 1.2 bar, but he can't achieve it. Are you serious? If the ACTUAL is below the TARGET , what does that probably mean?!

Yes, sorry, I expressed it incorrectly .

A4CabCH wrote:

But the wastegate valve, hoses, SUV, and N75 were just checked by an Audi enthusiast (a trained mechanic and RS specialist) and found to be OK!

Simply checking the wastegate valve is not enough. In the 1.8T, the mechanical part of the wastegate, including the valve and/or manifold/shaft, wears out. Therefore, remove the downpipe and check if the valve isn't wobbling around like a spring in the wind.

This forum is for people who like to work on their vehicles themselves.

Everything else is pointless if someone (sorry) doesn't have any knowledge; how can they then evaluate the statements of others or offer them advice? Not at all, because it's simply not possible.
A vehicle diagnostic system is a tool for repair, just like a wrench, and not some magical device for giving professionals instructions with clever sayings.

This is neither meant to be malicious nor demeaning, but it is the reality.

Best regards, Rainer.

TDI-GTI-4-Motion wrote:

A4CabCH wrote: But the wastegate valve, hoses, SUV, and N75 were just checked by an Audi enthusiast (a trained mechanic and RS specialist) and found to be OK! Simply checking the wastegate valve is not enough. In the 1.8T, the mechanical part of the wastegate, which includes the valve and/or manifold/shaft, wears out. Therefore, remove the downpipe and check if the flap isn't wobbling around like a spring in the wind.

ok, understood! So, it will be checked as soon as the gentleman has time.

"I have a question about this: Why does the performance sometimes seem completely normal without any issues? I don't understand that... because if something is broken, shouldn't it always malfunction, not just occasionally?" Or could it be due to the software?

dieselschrauber wrote:

This forum is for people who like to work on their vehicles themselves. Everything else is pointless if someone (sorry) doesn't have any knowledge; how can they then evaluate the statements of others or offer them advice? Not at all, because it's simply not possible. A vehicle diagnostic system is a tool for repair, just like a wrench, and not some magical device for giving professionals instructions with clever sayings. This is neither meant to be malicious nor demeaning, but it is the reality. Best regards, Rainer

Unfortunately, not everyone has their own workshop and/or millions of dollars. That's why I have to do things myself. I have the technical understanding and the willingness to learn, but I'm lacking a lift and the right tools. That's why I have to have more complex tasks done by someone else. I can replace the N75 valve and check the hoses myself. Since I've already taken my car to several workshops and no one had any idea or seemed willing to really find the problem, I'm going to try to fix it myself.

Of course, I wouldn't mind if someone could check the entire system with me and explain a few things. I'd be happy to travel a bit for that. And I can think of something in return... maybe someone needs something transported or a paint job done (links allowed?).

I hope you understand me a little better now... it's not that I don't want to... It's also not so much that the turbo (if it were) absolutely shouldn't be replaced, but more that I want to identify the root cause of the problem. Because why a new turbocharger when it might be the software, for example, or vice versa,...

A4CabCH wrote:

Question for understanding: Why is the performance sometimes completely normal without any interruptions? I don't understand that... because if it's broken, shouldn't it always malfunction, not just sometimes? Or could it be due to the software?

If the flap is just a little bit better positioned and seals properly, then it works.
Cracks often occur in the exhaust housing, which expand depending on the temperature, leading to increased losses. It would also fit very well with your behavior (the warmer it gets, the worse it is).
You can, however, see everything clearly when the downpipe is removed.