Passat 3B: Engine Cut-off at 80 km/h

Good day!

It's a Passat 3B (engine code AVB) with 101 horsepower and 129,000 kilometers on the odometer.
FIN: WVW ZZZ 3BZ2P 1273xx
While cleaning the engine, I noticed that the EGR valve is completely covered in oil on the outside.
I disassembled it, cleaned it, and reinstalled it with new seals!
During the subsequent test drive, there was no power in either the low or high RPM range!
I then removed the mass airflow sensor (MAF) and cleaned it with brake cleaner.
Slight improvement, I got a new LLM, but it didn't help!
Read the fault memory using VCDS - no error codes found!
Starting at 80 km/h, you hear a slight hissing sound, followed by a loss of power. On a flat road, the maximum speed achievable is then only 120 km/h.
Bergauf maximal mit den 1. Walkway accessible!
Unfortunately, I won't be able to perform a VCDS log until Saturday. Also, which measuring blocks are crucial for diagnosing the performance loss?
Does it make a difference to close the EGR valve for testing purposes?
Until the AGR valve cleaning, it ran perfectly fine, I don't understand that!
I've made sure everything is connected correctly, and I've checked the vacuum hoses!

Thank you in advance for your assistance!
Hi Andreas from Vienna,

andy1609 wrote:

I've made sure everything is connected correctly, and I've checked the vacuum hoses!

You haven't. I bet there's a vacuum hose that's open, and that's causing the boost pressure regulation to fail.

Could you temporarily block off the AGR valve with a piece of metal?
I've also experienced this with an electric EGR valve before. Before cleaning it, it would sometimes fail intermittently, but after cleaning it thoroughly, it stopped working completely. }

Thank you for your answers!
Starting tomorrow, the car will be available again. I will follow your advice and first check the vacuum hoses and then seal the EGR valve!

andy1609 wrote:

Good day! While cleaning the engine, I noticed that... It was running perfectly fine until the AGR valve cleaning, I don't understand that! I've made sure everything is connected correctly, and I've checked the vacuum hoses! Best regards, Andreas from Vienna

.

Yes, yes, engine washes are a great thing. Afterwards, the engine looks wonderfully clean on the outside, but often things inside are very wet, or the pressure washer has dislodged, severed, or even punctured something.

Besides checking the EGR valve and its vacuum hoses, you should also look for loose connections in other areas.

haithamina