Installation of the new mass airflow sensor

Hi everyone,

Since my old mass airflow sensor was broken, I bought a new one.

Is it enough to just replace the LMM itself, or do I also need to replace the entire 'housing' or 'assembly' that it's installed in?
Best, Björn.

Hello, normally you don't have to replace the pipe, unless for example the grid at the pipe inlet is damaged. If everything is okay, then simply replacing the measuring instrument should be sufficient.

[quote='SirBiBi']Hi ALL,

Since my old mass airflow sensor was broken, I bought a new one.

Is it enough to just replace the LMM itself, or do I also need to replace the entire 'housing' or 'assembly' that it's installed in?
Best regards, Björn[/quote]

A Hot Film Mass Air Flow sensor (MAF) consists of a tube within which the actual measuring device, i.e., the hot film element, and in some gasoline engines, also suction diesel engines, an NTC thermistor is calibrated. If you disconnect the measuring element from the tube, it becomes practically unusable. It will be miscalibrated and will not display the accurate air mass values. This can lead to reduced performance, excessive exhaust gas recirculation, and the engine 'stalling' within the smoke reduction system.

Sure. Here's the translation of the text from German to English:

'Gr.W.'

Quote:

If you detach the measuring element from the pipe, it becomes practically unusable. It will be misaligned and will not display the accurate air mass values. In the worst-case scenario, this can lead to reduced performance, excessive exhaust gas recirculation, and the engine "stalling" within the smoke limitation range.

Hi W.

The older TDI mass airflow sensors cannot be easily removed from the intake manifold, so they retain their calibration until a (pointless) forceful intervention is applied.
In the newer models, a small sensor is inserted into the pipe and secured with screws.
Unlike the ESP (which has a triangular screw that is difficult to open), the new sensor element can be disassembled using standard tools. Can a replacement part really be "installed incorrectly" (resulting in measurements outside of the tolerance range) in this case?
Then Bosch services should also have mass airflow sensor (MAF sensor) testing equipment for these parts.
(similar to pump start-up procedures)?

Hi,

I was almost expecting that, Wilhelm. I've now installed the new LMM without the tube. Your tip, unfortunately, came a little late .
'But no worries. My car actually has noticeably more power now than it did before the replacement, so I'm completely satisfied.' Next time (hopefully not too soon), I will replace the pipe.

See you, Björn.

@Ulf:

Yes, with the newer LMMs (HFM LMMs that are inserted into the pipe), no adjustments are necessary. How and where exactly should that happen within the factory?

Furthermore, the oval shape of the measurement plate dictates its orientation, and the precise position within the airflow is, in my opinion, not crucial to within 0.1mm.

Okay, no problem to change it like that!