Turbocharger Failure? AFN Engine Problems

Hey everyone, after being parked for about 5 months, I drove my A4 today for the first time. After a trip of about 100 km, I accelerated fully on a country road after a curve. Suddenly, there was a loud 'puff' from the front left. The car had almost no power left. Also, it was making a terrible sputtering noise. There was black smoke with white particles coming out of the rear hatch. It starts, but with a lot of sputtering, if I try to accelerate below 1800 RPM.
Yes, the engine has been chipped, which adds about 40 horsepower. It lasted for approximately 20,000 kilometers.

What do you think, does it sound like a turbocharger or something else? It's a Garett VNT 15...

Hello,

'No, it doesn't sound like your turbo has failed, but rather one of the pressure hoses. Check the hoses connecting the turbo to the intercooler and back to the turbo. One of the hoses may have slipped off or burst. You might be able to identify it by a slight oil leak.'

You should probably stop driving it, because the turbocharger is not building any pressure anymore, and the engine is being forced to work at full throttle all the time, which can quickly lead to the turbo over-spinning...

Have fun searching!
- Private

Okay, I'll check that out right away. I just heard from someone else that it might be the head gasket... But if it were the head gasket, it probably wouldn't have made that 'puff' sound. It also sounded like a hose might have burst.

The connection between the LLK (likely referring to a specific component) and the pressure pipe consists of a rubber hose secured with two quick-release clamps. This connection seems unable to fully withstand the pressure in the system. This connection frequently comes loose. Using standard hose clamps (the type tightened with a screwdriver) permanently solves the problem.

The statement about the turbocharger over-boosting in this scenario is not entirely accurate. Once the hose is completely detached, the turbocharger cannot over-boost because it lacks the necessary exhaust enthalpy. This is simply because the engine no longer receives the amount of air required for the combustion of the full-load injection quantity. Although the injection quantity is not limited (as the engine control unit does not detect the reduced air mass), most of it is incompletely combusted and exits the engine as soot, thus not contributing to the necessary exhaust energy. Furthermore, the limp-home mode is activated relatively quickly and limits the injection quantity to 25mg per cycle.

It becomes dangerous for the turbocharger only when the intercooler hose bursts or comes loose. In that case, the full exhaust energy is still present, the turbocharger spins freely, and in the worst-case scenario, it can burst due to overspeeding.