1.9 TDI ATD (Golf 4), 74 kW: Fuel consumption/top speed -> faulty mass airflow sensor

Hello,

We have a Golf 4 TDI, manufactured in May 2001, with 120,000 km on the odometer. We are experiencing the following problem: The fuel consumption during normal driving is 6.5 liters per 100 km. When comparing it to a similar Seat TDI (110 hp) under the same driving conditions, the fuel consumption was 5.0 liters per 100 km. In addition, the car consistently remains 4 km/h below the maximum speed of 188 km/h (measured via a GPS device) when driven on a straight road, despite repeated attempts on different days.

The draft seems subjective, but it certainly seems accurate, especially below 3000 RPM.

Here is a graph showing the LMM (lambda-minus-minus) values in third gear as a function of engine speed.
" color="red">Bitte keine Links zu externen Dateihostern! a) nerven die zusätzlich notwendigen Klicks, b) Wartezeit, Werbebanner/Werbepopups und notwendige Registrierungen, c) ist nach einiger Zeit die Datei weg und das Thema für andere Leser nutzlos!

Bitte nutze 'Attachment hinzufügen' bzw. das Upload Forum hier.

Okay, let's create a proper log. You can't do anything with these values.

If you have a VAG-Com, please perform a log with the following settings: 003-008-011 (see the technical article). Then you can clearly see where the problem lies.

Hello Bastion,

Contrary to your statement, the "technical article" we read earlier recommends reading measurement blocks 8 and 10 when there is a suspicion of LMM (likely referring to a specific measurement or system).

What is correct now?

Best regards,
t-evergreen-i

Blocks 3, 8, and 11 are more informative because they provide more insights when it comes to identifying performance issues.

"Question: Did you lose focus because there was a brief dip in the log at the end?"

bastion wrote:

Question: Did you lose momentum because there was a brief dip in the log at the end?

Okay, you can see from the logged throttle position that a switch was activated here.

What amount of air does your vehicle intake at full throttle (approximately 4000 RPM)?

bastion wrote:

Blocks 3, 8, and 11 are more useful because you can gain more insights regarding performance issues from them.

And what specific insights does MWB 3 provide in the case of performance issues?

It's already been clarified, Ulf!

We are waiting for the logs!

I drive the same Golf, but it's a model from 2004 (engine code: ATD / gearbox code: EUH).

To achieve a fuel consumption of 6.5 liters per 100 kilometers, I have to drive at least 160 km/h or faster.
My "normal" consumption at speeds of 90-100 km/h is between 4.5 and 5 liters for a distance of 35 km.

Furthermore, there's a difference depending on whether you're driving a PD-TDI or a VP-TDI. The latter is quite a bit more economical.

I'm also having issues with the top speed: I'm not reaching the 188 km/h stated on the documentation; according to the GPS, the fastest I've been is 180 km/h (but it doesn't really bother me).

Code:

Drehzahl / MAF / Air Intake / Throttle 4032   823,2   1927,8   100

What amount of air does your vehicle consume at full throttle (approximately 4000 RPM)?

3 Phasen Biber wrote:

I can provide you with the following measurement block, where the value is 823.2:

I'm planning to conduct a new measurement test sometime in the middle of the week.

The air mass should be significantly above 1000 mg/r at ~3000 RPM, which I don't see in your log.

@ Mullemaus
"With a 74 kW engine? I've never seen that on an AVB before!" Are the differences that significant?
I am unable to translate "haithamina" because it does not appear to be a word or phrase in the German language. It may be a misspelling, a proper noun, or a term from a specialized field. If you can provide more context or clarify the intended meaning, I would be happy to assist you with the translation.

@ Mullemaus
'With a 74 kW engine? I've never seen that on an AVB before!' Are the differences that significant?
haithamina

You can already notice 300mg/r (as an example) quite clearly . VW specifies 850mg/r as the limit, and they replace anything below that .

@ Mullemaus
Okay, so while I see values above 850 mg/R on my own equipment, even in the summer at 30°C, you wrote that at 3000 RPM, the values are significantly above 1000 mg/R. I have never seen that before.
I am unable to translate "haithamina" because it does not appear to be a word or phrase in the German language. It may be a misspelling, a proper noun, or a term from a specialized field. If you can provide more context or clarify the intended meaning, I would be happy to assist you with the translation.

What does it look like when you use the SEARCH FUNCTION ?

http://www.dieselschrauber.de/Solldaten_4_Zylinder_PD.html

ATD/AXR (full load) -> MKB 10.1 = 800-1100mg/H

Okay, what's shown in the log is perfectly fine, as it clearly indicates a value well above 800mg/H.

Great, Bertil.

"I know the theoretical values, which correspond to the AVB specifications. However, in reality, I have never seen values exceeding 1000 mg/m³ at around 3000 RPM, even at sub-zero temperatures. That's the issue here!" Can you provide real-world measurement data?
haithamina
P.S. I also think that the LMM mentioned by the original poster here is okay!