ALH vs. LMM: What's the difference?

Hi fellow mechanics,
Maybe someone can help me out sometime...
Engine is a 1.9 TDI 66kW "ALH" in a Golf 4...

And specifically, when you connect VCDS, you can check how closely the actual value of the mass airflow sensor (MAF) matches the target value.
It's a well-accepted test for assessing the condition of the mass airflow sensor.

While the engine is idling, the value will eventually increase, meaning that the air mass exceeds the target value.
If you lightly press the accelerator pedal, the values will equalize.
"During normal driving," the values are always the same (assuming you can read them quickly enough).
The maximum actual and target values are slightly above 1000, at a medium speed and full load.
When the engine is revved, as long as it's willing/able, the actual value starts to drop off around 3000 RPM, resulting in a loss of approximately 1/4 of the expected value.
"When stationary, and at the specified idle speed, the output is also missing approximately 1/4 to 1/3 of its potential. The target value is around 800, while the actual value is around 600."

I'm really confused right now, is my mass airflow sensor broken or not????
Or does it rather suggest a leak in the vacuum hose, considering that this engine doesn't actually have a VTG turbocharger (I'm not sure, I'd need to take a closer look).

I'll send you the VCDS-DRV version. How do I enter it in the profile? There's no field to fill in...

Best regards,

Hi,
a first response.

Quote:

While running in place, after a while, the value increases, meaning that the air mass is above the target value. If you lightly press the accelerator pedal, the values will equalize.

That's normal. After a few minutes, the AGR (Abgasrückführung) shuts off, but it turns back on after a sudden acceleration.

Quote:

I will send you the VCDS-DRV version later. How do I enter it in the profile? There's no field to fill in...

Yes, there is. The box above the text "Without a valid serial number...". At least, that's where I entered my number.
Sure, here is the translation of the text from German to English:

"vg"

This is a common abbreviation for "very good" in German. It is often used in online forums and chat rooms.
Herbert.

PS - The actual value being too low (over 3000 min-1) can have several causes. What are the target and actual values for the boost pressure?

Wow, that box looked like it belonged to the "Interests" section .

I need to check the turbo boost pressure, but I haven't even thought about it yet, and my car battery is so drained that it's a bit awkward to check it while driving .

I'll do that, thanks for now.

I did a log with boost pressure readings.
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

I can't include any graphics here at the moment (there seems to be a problem between the keyboard and the chair ), but here's a brief summary of what I've noticed about Scope:

Boost pressure below target when stationary.
While driving, it's often within the normal range, but under full load, it goes above the target value and seems to quickly settle back down.

Maybe someone could take a look at it.
I find tables a bit difficult, but I find it easier to work with diagrams .

I suspect there might be a problem with the (vacuum) hoses in the engine compartment.
They look great, but you can't see anything through the fabric covering.
My speedometer recently stopped working because a... rodent had "cut" the cable .

Hello,

Please name the file "xls" as "xls" and not as "csv". It's best not to make any unnecessary changes to the file.

Quote:

Charging pressure below target at idle.

Normally, without exhaust gases to drive it (i.e., with insufficient exhaust gases), the turbocharger cannot build up pressure.

The log seems to indicate a problem with the VTG (Variable Turbine Geometry) system, but you can check if the vacuum hoses are clear and not kinked.

Best regards, Rainer.

By default, the file will be named .csv.
Inside the VCDS folder, there's a RossTech program that creates a file named "normal" (previously, it created a "Links" data mess). I saved it as a .xls file... I don't know why it's now a .csv file again, but shouldn't that be okay since it's now readable?

The hoses are clear and not kinked.
When would one of them be most likely to "leak"?

I'm going to take a look at the loader now; I didn't even know it was a VTG! *embarrassed*

Thank you for looking.

Your title was:
"ALH > LMM MWB, unclear."

The MWB 3 not only confuses you.
In idle conditions, the often opaque activities or inactivity of the AGR often...
Regarding deviations - under full load and high speeds, the actual value eventually decreases.
below the target value, but that's not a problem and is normal.

Wenn du den LMM prüfen willst, nimmst Du besser die MWBe 8 und 11. As soon as.
Under load, the boost pressure is regulated, and the soot reduction system in section MWB 8 must not exceed...
represent the lowest value - especially not near the maximum value (Vmax).
When the soot emission limits approach the torque limits,
Could it be that the mass airflow sensor needs to be replaced? That would also improve...
Response behavior under load changes.

Best regards, Klaus.