A3 BKD, boost pressure regulation limit exceeded

Hello.


'The other day, a friend came by with his 2004 A3 with a BKD engine to have his winter tires installed. From day one, this car has been an absolute disaster (4 or 5 turbos, 4 AC compressors, 2 cylinder heads, and an engine block all replaced at 204,000 km). Initially, it had inexplicable power losses, which led to the replacement of the turbo and a bunch of other parts. A few weeks later, the second turbo gave up (oil leaking into the exhaust). Then, the cylinder head broke, and just a month later, the engine block cracked (a crack between two cylinders). After that, someone forgot to tighten the torque strut, and after 20 km, the engine 'seized.' There were also numerous minor issues, and a piece of the air intake system ripped off. But now, it's actually running.''Usability' problem is likely that it goes into limp mode regularly at around 2000 RPM and with a slight acceleration under partial load... The error code then always indicates 'boost pressure regulation limit exceeded.'


ich hatte noch keine wirkliche Zeit um danach zu schauen aber so auf den ersten Blick sieht alles 'ok' aus. Die unterdruckleitungen sind dicht Ladeluftsystem konnte ich noch nicht abdrücken aber an dem Übergang vom Schlauch zum Ladeluftkühler (der vom Turbo kommt) hängt reichlich öl/dreckpampe. Das Gestänge der Druckdose/vtg habe ich mit dem finger paar mal bis von Anschlag zu Anschlag hin und her bewegt. Da 'There was no resistance or obstruction, and the force was consistent and easily movable with just one finger.'

'VAG can't find any errors, and I'm not really knowledgeable about troubleshooting with diagnostic tools (TDIs).'


What I've noticed is that when accelerating from idle, it makes a very loud turbo whistling sound. It's not a hissing sound, but more of a whistling noise like you hear from larger turbos under high load (like in trucks). However, you don't hear anything while driving.


I want to now set up the basic configuration of MWB11 and see what results I get.

Are there any other general tips on how to approach troubleshooting this issue? Should I compare the desired and actual boost pressure values?


Thank you.

Best regards,
Marc

If the old turbocharger was leaking oil into the exhaust, it's possible that this has clogged the catalytic converter.
They really don't like oil.
Okay, let's loosen the three screws on the flange and then take it for a test drive.
To rule out a problem with the turbocharger's wastegate control line, you can temporarily lock the variable turbine geometry (VTG) in its "aggressive" setting and then carefully perform a test drive while recording data.

I can only confirm the diagnosis of a faulty catalytic converter. After replacing the catalytic converter twice, the breakthrough came with the third replacement. Before the catalytic converter was replaced, the error message appeared almost every time you pressed the accelerator pedal even slightly from low to medium RPM, i.e., practically every 10 km. Since the catalytic converter was replaced, there has been no further issues for about three-quarters of a year.
Okay, I'm ready. Please provide the German text you want me to translate into English.

That would be world-class... and now even the trash is piling up.


Does it not have pressure sensors or something similar in the exhaust?

no.