LLM & AGR Values: Are They Accurate?

AFN engine in an A4 B5, AGR valve is not disabled, and everything on the engine is original.


The target value for the LLM is approximately 280 in the LL, but the actual value is between 460 and 500. During the actuator test, the AGR valve opens and closes properly, which can be easily observed from the outside of the engine.
According to the measurement data block, the AGR (Abgasrückführung - exhaust gas recirculation) should be approximately 60% open in the LL (Leerlauf - idle), but it doesn't appear to be when I look at it from the outside. At best, it seems to be open only about 5-10%. At least, that's my impression.
Using the manual pump, I fully opened the AGR valve in the low load range, and then the value from the mass airflow sensor (MAF) almost perfectly matched the target value.
But why isn't the AGR valve opening properly? As far as I can tell from watching the pump, it's not sticking; it's opening and closing smoothly. However, I think the vacuum pressure applied to the AGR valve is too low for 60%. The vacuum pump on the engine seems to be working well, according to my measurements.

So, I'm assuming that the mass airflow sensor (MAF) is still okay despite the strange values? Or can that only be determined with a test drive?
I'm still looking for a power loss. The small check valve before the VTG (Variable Turbine Geometry) is broken again. I replaced it a few years ago, and last week when I replaced the vacuum lines, it was still okay.

First, check if the vacuum system is airtight. If it's not, all actuators will receive insufficient vacuum pressure.
To completely rule out the EGR valve as the cause of the power loss, temporarily seal the EGR valve with a metal plate. (Use the search function for instructions).

Create a log from measurement block 03, 10, and 11, recording data at full throttle in 3rd gear from 1200 to 4000 RPM.

Today, I had to deal with the vacuum reservoir on the VTG again; it's defective, and the connection fitting has a crack. The new one is supposed to arrive tomorrow. I'm curious to see if that's all the problem is; hopefully, yes. It's funny that the reservoir is cheaper than the old check valve before it.