LMM: Resistance and Challenges

Hello!

My flow meter has 2 terminals and a resistor symbol.
What is this for, and what kind of value can be put into it?

My engine is a 1.9L, 81kW, AHF model, manufactured in 1999.

Hi Karl,

http://members.chello.at/35fd001/DCP_0910.JPG

Hi.

I don't understand your intention.

I can't see any symbol of resistance in the photo.

Generally speaking, LMMs (Lambda Measuring Modules) are calibrated at the factory in such a way that no subsequent adjustments are necessary; in fact, any such adjustments would disrupt the air-fuel mixture calculation.

If an LMM (lambda oxygen sensor) is not working correctly, you can try cleaning it with brake cleaner spray before replacing it.

I can't see any resistance symbols in the photo.


Oops...

bad eyes or bad monitor?

Do you see the two metal 'clips' to the right of the rubber seal?

These two brackets are connected to the resistance symbol.

I'm also wondering what's supposed to be done there...

CU Gremlin.

Gremlin wrote:

Do you see the two metal "clips" to the right of the sealing strip? These two brackets are connected to the resistance symbol.

Hi.

I think the two brackets are well-placed, but what about a resistance symbol?
For me, this looks like a rectangle with a connecting line on each of the shorter sides, which presumably should lead to the brackets here?

Well, maybe we're all just seeing a different "inkblot" here: everyone sees something different...

The terminals might potentially be used to control certain internal voltages... this is purely my hypothesis, because under normal operation, nothing should be connected to them externally.

Hi,
presumably a matching resistor to adapt the LMM to different boundary conditions.

@Karl:

If you like, you can try adding a few resistors (e.g., 10k, 47k, 100k) in series and measure how much the output signal changes (voltage value).

If there is no change in the output voltage, the resistor could also be considered as part of a filter, through which the response characteristics of the mass flow meter can be modified.

Best regards, Rudi.

Hello.


The mass airflow sensors (MAF sensors) for TDI engines and gasoline engines are almost the same. However, the MAF sensor for gasoline engines has an additional air temperature sensor at the location shown in the picture. This temperature sensor is not present on MAF sensors for TDI engines.

At least, that's the case with the newer LLMs.

Best regards, Georg.