With the new LLM, even lower values?

Hello,

I experienced something quite curious again.
My LMM reading was just under 800mg at 3000 rpm, which is right at the edge of the acceptable range. I was just thinking, maybe you should buy a new one...
The workshop installed it (under warranty), and sure enough, the new one shows even lower values!
I didn't even reach 800mg; the maximum I could measure was 775.
I had previously deactivated the EGR valve and plugged the hole in the suction hose. It's understandable that the mass airflow sensor would then show a different reading. The bypass of the KGE is no longer an option.
What could be the reason for this now?

Best regards.
Ronny.

By the way: AFN in the Passat.

Hi.

How about things like...?
- Air filter clogged.
- Suction nozzle clogged (leaves?!).
- Insufficient supply voltage for the mass flow meter = loose cable or corroded connector.

What does the boost pressure say? When there are problems with the charger and the pressure is too low, naturally, not enough air is being drawn in.

Hello,

'The turbocharger is new, the intake manifold is free of obstructions, and the boost pressure measured between 1907 and 2029 mbar in four measurements.' Of course, after subtracting the generally prevailing atmospheric pressure...
On Friday, I made an appointment. Let's see if the workshop can find anything.

Best regards.
Ronny.

Hi, my tuner has had similar experiences a few times when replacing MAF sensors for customers. The new ones also showed low readings. They were simply defective. Even though it sounds quite unbelievable, it was the case, and it has happened more than once. Just go to the dealer where you bought the MAF sensor and have them perform a measurement. If it also shows too little information there, you can exchange it.

I've also considered the possibility that the new part is defective.
He hasn't been paid yet, let's see what they say on Friday. Luckily, I know the people at the workshop pretty well. And I certainly won't spend x hours troubleshooting if the problem is only with the new part.
By the way: The measurement I took was done using the 1551 model from the retailer. They are definitely not calculating any other values.

Hello,

Okay, for those who are interested, here's the report after the car was at the workshop:
You haven't found anything at all!
Approximately 725,000 sets of measurement data were read and analyzed, and it was found that occasionally there were inconsistencies. The current theory suggests that there is likely an electrical problem somewhere.
My friend will probably watch that sometime when he has too much free time.

Best regards.
Ronny.

By the way: Maybe someone is interested in a beautiful Passat from '98?

Hello,

An AFN does not have 725,000 measurement data blocks. If they have taken so many measurements on those perhaps 10 relevant blocks (see also the error database), then something is definitely wrong with the workshop.

Just check the supply voltage of the mass flow meter with a multimeter. Should be +5.0 V (I believe, but I don't know for sure; I'm just assuming this because, for example, external boost pressure sensors are also powered with +5V).
If the measured value is lower, no mass flow meter in the world will provide a reading higher than the supply voltage, and therefore it may indicate a value that is too low.

Best regards, Rainer.

Hello,

@Micheal II:
Of course, 725,000 was meant ironically. I could post the note I have, if you'd like.

@Rainer:
Okay, I'll translate that. Does it work to measure the voltage with the connector unplugged, or does the mass airflow sensor (MAF) need to be connected?

By the way: The old mass airflow sensor is back in the car. It still delivers better performance than two new ones.

Best regards.
Ronny.

Hello,

To measure the supply voltage, simply turn on the ignition and disconnect the mass airflow sensor.
You can easily identify the mass pin by measuring the resistance against the battery's negative terminal; it's the one with the lowest resistance. However, it's best to turn off the ignition to avoid damaging your measuring device, as the +5V voltage could interfere with the resistance measurement. You don't know which pin on the MAF sensor is the 0V (ground) pin. If you happen to have a wiring diagram, that's even better, but measuring it is likely to be faster than finding one.

Best regards, Rainer.