mal wieder Lmm | Posts 16+

'@kruegerjan: The 'wire' you are referring to is the temperature sensor attached to the outside of the mass airflow sensor; it looks like a regular silicon diode (e.g., 1N4148).'

It's not present on the 1.9 TDI with a variable valve lift (VEP) engine, but it is present on the V6 TDI engine, although the signal isn't used.

Stefan.

Regarding the topic of LMM.

I received my sixth set of tires today in just a year and a half; the last set only lasted 4,000 km or 2 months!
The measurements were far below 600mg!
The modification regarding afterglow has already been done on my vehicle a long time ago.

Okay, the mass airflow sensor is still under warranty right now, but it really can't be that.

My mechanic said that Audi is now measuring the air mass again using a vacuum system because the mass airflow sensors (MAF sensors) haven't proven to be reliable. Is there any truth to that?

What alternative would there be for a 12/98 AFB then? I can't and don't want to stock up on several mass airflow sensors just because they keep breaking down.

Then I will sell the box and buy something Japanese...

Stefan.



It's increasingly frustrating to see workshops constantly replacing Mass Air Flow (MAF) sensors! Even after the second replacement in a short period, I would start to worry and investigate whether there might be another underlying issue. Often, it's a leak in the intake manifold before the compressor. In such cases, some of the air is drawn in *after* the MAF sensor, so it's not measured by it. In my 7 years as a diesel engineer, I've driven countless test vehicles. I don't know of a single case where the MAF sensor was actually defective. A lack of power always had other causes than the MAF sensor!!!

Hi,

Ben1972 wrote:

...In my 7 years of experience as a diesel engine developer, I have driven countless test vehicles. I don't know of a single case where the mass airflow sensor (MAF) was defective. Power loss always had different causes than a faulty MAF!!!

Interesting statement! I know of some test vehicles that were provided to us where the mass airflow sensor (MAF) was definitely defective. These vehicles are not repaired in workshops but by the manufacturer. I assume that the repairs were carried out properly. Some of these cars even came from your place of residence.

Sure, I don't want to deny that often errors are attributed to the mass airflow sensor (MAF) that it didn't actually cause. However, if you measure an air mass that is far below the tolerance range and then, after replacing the MAF, it falls within the middle of the tolerance range, then I do think that the MAF had a problem.
Unfortunately, when replacing the mass airflow sensor (MAF), the intake manifold is moved. A crack (in the intake manifold after the MAF) might be closed again after the replacement and could potentially reappear after some time of operation. This would then cause the errors you described.

Hello Bertil,

I completely agree with you, especially after having experienced some LLMs recently.
The measurements indicated a defect (possibly due to wear and tear), and it was replaced.
Everyone experienced improved measurement readings and performance afterwards, and that was all.
persistent. I can't imagine that such cracks would...
temporarily closes to a significant extent due to changes in the LMM (likely referring to a specific system or process).
Bosch mass airflow sensors are useless. VAG would be well-advised to stop using them, even for existing vehicles.
to select an alternative manufacturer for the vehicles being delivered.
This afternoon, we plan to conduct a measurement test using an Octavia.
66kW, manufactured in 1999, with 150,000 km mileage. Unfortunately, the car has not had a complete service history ('service booklet') up until now.
'maintained'. Contacting VAGCOM was unsuccessful - trim pieces.
disassembled - diagnostic connector cable torn cleanly through!!

Hello Jürgen,

dem will ich nicht widersprechen. Ich kann mir das aber irgendwie nicht vorstellen, dass jemand innerhalb 1,5 Jahren 6 LMM wechselt. Wenn so ein Teil bei 150000km ausfällt, ok, da geh ich mit, aber nicht nach 4000km und das 6x hintereinander. Something is wrong.

Best regards, Ben.

Yes.

Sure, there's something wrong.

Don't forget, it's a V6 TDI engine, which is inherently prone to mass airflow sensor (MAF) failures.

The mass airflow sensors were all measured BEFORE the replacement and diagnosed as having significantly lower-than-expected values.
After a new mass airflow sensor (MAF) was installed, the air mass was measured again, and values significantly above the minimum threshold of 850 mg were recorded.

Subjectively, the change was always noticeable through a feeling of 'new power,' reduced fuel consumption, and more even acceleration.

I've also wondered if maybe I'm just not smart enough to drive, that these things always break down; but the car isn't even modified, and except for a faulty AGR valve, everything else is original and brand new! (The engine now has about 40,000 km, the ESP has about 10,000 km, and the turbocharger was just replaced today).

The entire hose system has already been pressure-tested and checked for leaks (using overpressure and a pressure gauge); therefore, nothing is lost in that regard. As a precaution, the hose between the mass airflow sensor (MAF) and the turbocharger was replaced due to the beginning of crack formation under the hose clamp (although there were no actual leaks), but that didn't change anything either.

I want to almost completely eliminate the possibility that air is bypassing the mass airflow sensor somewhere.

Well, let's see how long this one lasts...

Stefan.

P.S.: When the warranty expires, I'll buy something Japanese...