Relationship between LMM and boost pressure?

Hi,

just a small, general question:

Does a faulty mass airflow sensor (MAF) cause an 'incorrect' boost pressure curve?
Alternatively: If I experience a loss of power during acceleration and observe that the boost pressure is decreasing, can I rule out the mass airflow sensor (MAF) and continue troubleshooting the boost pressure control system?
Or, to put it another way: if I still observe a correct boost pressure and pressure curve despite a drop in performance, does that strongly suggest a faulty mass airflow sensor (MAF)?

It's just a question - I don't have any problems with my TDI.

Best regards.
mortl

Hello mortl,
Your question is not so easy to answer, as it's essentially a classic "chicken or the egg" problem.
If the mass airflow sensor (MAF) provides a reading that is too low, the fuel injection amount will be reduced. This, in turn, results in the turbocharger lacking the necessary power.

You see, it's not that simple. However, even with a faulty mass airflow sensor (MAF), the target boost pressure should be reached at a moderate engine speed of approximately 2500 RPM, as at that point, even with a reduced fuel injection volume, there should still be a sufficient mass flow rate and enough enthalpy available.
If the boost pressure is not properly regulated above 2500 1/min, I would not look for the problem in the mass airflow sensor.
It is certainly possible under those circumstances. However, there are unfortunately still many other potential sources of error. To rule out the LMM (likely referring to a specific component or issue), the diode method proposed by DocSnydor might be a cheap solution.

Regards,
Alex.

Hi,

Just a small note: The trick with the diode doesn't originate from me (unfortunately), but from 'Georg_G'. I don't want to adorn myself with other people's laurels (or however the saying goes ).
I'm just the one among us who, due to being stingy, has had the most success with that approach. I won't be putting any more LMMs in my car (unless they happen to be on sale at Aldi). I just don't see the point... The fuel consumption is okay, the car doesn't misfire (the EGR valve was also removed), and it doesn't change anything regarding my problem with the delayed turbo boost.

@alex: What exactly does your AGR do? Still the same old song and dance as my 1Z?