LMM at TD4

Hello there!

"Although I don't currently own a VW or Audi, I still thought I would write. It seems this problem exists everywhere."
LMM

I'm looking for the wiring diagram for the mass airflow sensor (MAF) because I want to only connect the temperature sensor of the Bosch MAF to test how it affects driving and, especially, emissions values.
I found the information for some LMM in the article about the AGR, and also a picture of something that can be done, but I don't have a clear understanding yet. Is the temperature sensor in the MAF controlled separately, or is that not possible separately?
I have a Freelander 1 TD4 from 2002. I bought a cheap MAF sensor on eBay, and it improved the driving somewhat, but not as well as when there's no MAF sensor installed at all. I also have a new Bosch MAF sensor that I want to try, but first, I'd like to experiment with this one. I haven't been able to cut open the old MAF sensor yet to see its wiring, but somehow I feel that the airflow is being restricted too much.

VG
Matthias.

Hi,

"Nothing is being controlled there; those are sensors. The engine control unit uses the temperature reading for correction purposes, and if it's reasonably accurate, it doesn't have a major influence."

The simplest solution is to use the right LLM.

Best regards, Rainer.

Hello Rainer,

Danke fuer die Antwort und entschuldige die verspaetete Rueckmeldung. JA, den Bosch habe ich mittlerweile auch installiert, aber der Verbrauch wird immer hoeher, die Luftmessungen passen trotz allem nicht, wenn er abgezogen wird, ist's besser als mit. AGR neu oder gereinigt, PCV vor kurzem getauscht, Ansaugkruemmer sollte noch sauber genug sein. Ist nicht allzulange her, dass ich ihn gereinigt habe. It doesn't really make sense, unless the high-pressure pump is malfunctioning again.

VG
Matthias.

You need a suitable OBD diagnostic tool and a structured approach to obtain meaningful results.

Currently: Speculations, lack of knowledge, guesswork...

Is this okay, or do you need more information?

No, that's great; you can use that to check your assumptions about the air mass.

Okay, thank you.

It's strange that when the mass airflow sensor (MAF) is disconnected...
I'm getting significantly better air quality readings than I was before with the new Bosch part. I'm going to try replacing the rail pressure sensor. Recently, I found something where someone else had a similar problem and said that changing the sensor improved their readings. I had a Febi sensor installed, but it leaked because parts were missing, so the old one went back in.

Perhaps someone has an idea. I filled the tank completely on Saturday, then yesterday I installed the MAF sensor and in the afternoon, the new sensor. Now, after driving about 50 miles, I'm looking at the fuel gauge and it's already a quarter empty. There's nothing visible underneath the car, so I suspect it's related to the MAF sensor.
Two weeks ago, the fuel consumption was 12 liters per 100km when the mass airflow sensor (MAF) was connected. After disconnecting it, the consumption dropped to 8.5 and then to 7.6 liters per 100km, mostly in city traffic. The MAF sensor is new. I can't imagine that the sensor itself is faulty, so I will first disconnect the MAF again and test it. However, this will result in a fuel injection of -40 degrees Celsius.
The consumption shouldn't be this much lower. Also, it doesn't have any power anymore when that part is installed, and the automatic transmission is starting to jerk again. Is there no way to figure out which cable belongs to the temperature sensor?

You need a wiring diagram and a diagnostic tool. And with the support ticket, I will also explain what a motor control unit does.

Yes, that idea also occurred to me after I wrote it. I'm already trying to figure out where the wires from the mass airflow sensor (MAF) connect to the control unit, and if that's something that can be addressed through a support ticket, then that's a good suggestion, thank you.

Hello Rainer,

ich habe das Eingangssignal rausgenommen und werde das erstmal testen und aufzeichnen, bevor ich das Supportticket aufmachen, ich nehme an fuer techn. Support.

Best regards,
Matthias.

Hi Rainer,

I disconnected the input signal and took some measurements. The results are similar to what I got before with no input, but I can't say for sure if it's set to -40 degrees. The manufacturer hasn't given me any feedback on how to check that. The power consumption is quite high. I'll continue testing.

Greetings.