Air Filter LMM

I once inserted a hose with a diameter of 70mm directly into the air filter box. The air intake should have been optimal! Why isn't the mass airflow sensor (MAF) showing higher values? Is the MAF too small and unable to process more air? It could also be due to the grid in front of the MAF. Has anyone here had any experience with this?

I recorded everything using VAG software, and I'm consistently getting the same values compared to the engine speed and vehicle speed. I've also tested it without the air filter, but that doesn't improve anything either.


What remains is the feeling of having done everything perfectly, without achieving any measurable success.




nut cake

nusskuche wrote:

I once inserted a hose with a diameter of 70mm directly into the air filter box. The air intake should have been optimal! Why aren't the higher values displayed by the mass airflow sensor (MAF)? Is the MAF sensor too small and unable to process more air?

Depending on the software version, a good LMM (Linear Measurement Module) can, as far as I know, actually bring the measured value to the "scale limit," even with the standard suction nozzle.

Furthermore, the effect of removing the restriction only becomes noticeable above approximately 3500 rpm, where standard TDI engines exhibit a measurable vacuum in the air filter housing (around 50 mbar).
However, this is compensated for by the turbocharger, which ensures the same cylinder filling even with a restricted intake path. As a result, the thinner air flows faster through the mass airflow sensor (MAF), so that the measured value does not change.

The only benefit of de-stroking lies in reducing the load on the charger.
The increase in engine power (due to the turbocharger extracting less power from the exhaust gases) is more likely to be in the realm of academic, practically imperceptible, values.

By the way: even if you were to achieve a higher airflow through de-throttling would, it wouldn't result in increased performance -> technical articles on LLK tuning.