Faulty MAF Sensor: How to Diagnose

Hello,

My mass airflow sensor (MAF) in my Audi A3 TDI 90PS was replaced in the middle of last year because the old one was defective. I suspect that something might be wrong with the new one as well:
Since then, when accelerating (mostly with a cold engine) in the lower RPM range, around 1800-2000 RPM, there is occasionally a jerk or a surge/drop in power, accompanied by white smoke coming from the exhaust.

The workshop can't find anything because the problem only occurs when the car is being tested.

Can a defect be identified using VAG-COM by analyzing data from a diagnostic test, specifically when the event occurs? And which measured values (or diagnostic trouble codes) are most helpful for this?

Thank you very much, and best regards.
vdb

Hello, in the 3-meter meteorological observation tower, the air mass should be located at level 11, along with the low-level dryer (LLD), and something should be visible there.
Log the measurement range, including the error range, for a sufficient duration. Ideally, also log the value "3" alone occasionally to achieve a finer resolution.
I don't think white smoke is necessarily an indication of a faulty mass airflow sensor.

Quote:

My mass airflow sensor (LMM) in my A3 TDI 90PS was replaced in the middle of last year because the old one was defective. I suspect that something might also be wrong with the new one: Since then, when accelerating (mainly with a cold engine) from the lower RPM range, around 1800-2000 RPM, there is occasionally a jerk or a surge/drop in power, accompanied by white smoke coming from the exhaust.

I also had a similar case a while ago:
/viewtopic.php?t=14696&start=0&postdays=0&postorder=asc&highlight=herzog

Since I own a nearly identical car, I swapped the mass airflow sensors (MAF sensors) between the two vehicles. The fault then transferred to my car. After a few days, I also experienced occasional, sporadic misfires during driving, along with white smoke and a foul odor at idle.
The outliers could not be traced using VAG Com. To do so, you would need...
Real-time values.

Okay, so try replacing the mass airflow sensor (MAF sensor) with a temporary one for testing purposes. If your workshop installed cheap, low-quality parts from China, you should insist on a Bosch or original equipment (OE) MAF sensor.

Alongside this question, I had already ordered a mass airflow sensor (MAF) from Bosch. I installed it yesterday, and now I'm waiting to see how it performs over the next week.
What I noticed about the "old" one is that, where the Bosch label usually indicates the model number, the model number has been ground off on the old mass airflow sensor.
Are these items refurbished, and is it normal to sell one for €78?

Regards,
vdb

Quote:

Are these items refurbished, and is it normal to sell one for €78?

Exactly 78.00 + VAT is the cost of the LMM as an original replacement part. However, so far, I have apparently always received new parts from Bosch.

The price is similar at Bosch itself.