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Low LMM, Low Top Speed?

 
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Rico_Avant



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Post26-08-2008, 10:08    Subject: Low LMM, Low Top Speed? Quote

I replaced the mass airflow sensor (MAF) in my car, and it's showing good values up to 1000 mg/h, but for some reason, my air fuel bypass (AFB) is only reaching a maximum of 200-210 volts. The boost pressure is also correct. What could be the problem?


Translated on 20-09-2026, 15:19.
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matthiasTDI96
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Post26-08-2008, 10:26    Subject: Low LMM, Low Top Speed? Quote

Tell me... how are we supposed to know that?

"Someone who is so stingy with information cannot expect to receive much help in return."

What do the log data say? Without them, nothing will happen.

What is the engine's maintenance status? What do the air filter and fuel filter look like? What kind of tires are installed? Are there any other unnecessary accessories attached? How many kilometers has the car been driven?


Translated on 20-09-2026, 15:20.
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mserge
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Post28-08-2008, 14:46    Subject: Low Max Speed? Check New MAF Sensor. Quote

Rico_Avant wrote:
, also delivers good values up to 1000mg/h
.


I'll believe it when I see it; I haven't met anyone who's achieved a score over 800 yet.
A4 Avant 2,5 tdi 110kw; AFB; BJ2000
4 neue Nockenwellen bei 135 tkm!!
neuer Turbo bei 200.000km
neue ESP bei 216.000km
verkauft mit 225000tkm
jetzt Renault Espace 2,0 dci 172 Initiale BJ2012
Clio 2 RS 170 PS BJ2003


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Rico_Avant



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Post29-08-2008, 18:09    Subject: Low LMM, Low Top Speed? Quote

"Problem solved! I installed another new LMM, and sure enough, it's running now, with a speed of around 230."
Regarding the values, I drilled an extra hole to increase the airflow, and it's already working. And even without the hole, with a new mass airflow sensor (MAF), I've had several that have achieved 885-960 horsepower. I'm not sure where the problem lies.


Translated on 20-09-2026, 15:21.
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matthiasTDI96
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Post30-08-2008, 15:14    Subject: Low LMM, Low Top Speed? Quote

Okay, then...


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vwSchrauber
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Post21-07-2009, 15:00    Subject: Low LMM, Low Top Speed? Quote

Quote:
Why does the LMM have such a strong influence on the LD? Could it also be because the LMM indirectly also affects the EGR, and thus the turbocharger pressure control?


Low air mass value -> reduced injection quantity according to the enrichment/lambda value map -> lower exhaust volume flow -> less drive energy on the turbine side -> lower pressure build-up on the compressor side icon_wink.gif.
selber schrauben - statt Werkstattpfusch


Translated on 20-09-2026, 15:22.
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vagtuning
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Post06-08-2009, 19:01    Subject: Low Max Speed? Check Mass Air Flow Sensor. Quote




I want to see that; I haven't met anyone who has achieved a score above 800 yet.

New LMM and LDR valve:

Okay, I'm ready. Please provide the German text you want me to translate.


Translated on 20-09-2026, 15:23.
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dieselschrauber
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Post06-08-2009, 19:22    Subject: Low LMM, Low Top Speed? Quote

But 1000mg/hub at 2000 rpm, not at 4000 icon_smile.gif.


Translated on 20-09-2026, 15:24.
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Post06-08-2009, 19:45    Subject: Low LMM, Low Top Speed? Quote

Did I miss that the area where it occurs has been limited in terms of speed? icon_wink.gif


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dieselschrauber
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Post06-08-2009, 19:49    Subject: Low LMM, Low Top Speed? Quote

Well, I don't think he'll reach the missing top speed at 2001 rpm. icon_smile.gif

Thank you for the specifications of the OK motor.


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Post06-08-2009, 19:54    Subject: Low LMM, Low Top Speed? Quote

Point for you icon_wink.gif A Vmax of 2000 would be something nice icon_wink.gif.
How can I attach a second AT (automatic transmission) as a downstream stage to the car? icon_wink.gif

Okay, the engine's condition is just as questionable as it is for all others with 170,000 km on the clock and still have the original turbocharger... but considering the new mass airflow sensor, knock sensor, and coolant expansion tank, it's producing quite acceptable values, especially with its red emissions sticker icon_wink.gif. If I could just get rid of that knocking sound, I'm sure something isn't quite as it came from the factory.


Translated on 20-09-2026, 15:25.
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Post06-08-2009, 22:36    Subject: Low LMM, Low Top Speed? Quote

"Interestingly, the throughput usually correlates with the voltage, but in the case of those born prematurely, this relationship may not be linear anymore."
The logs clearly show that everything was running at full throttle, and yet the lambda value (LM) increases from 250 to 900 with n (engine speed).
Gruß, der Teileklaus
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christians
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Post09-08-2009, 16:08    Subject: Low LMM, Low Top Speed? Quote

"1000 mg/hub with a 2.5-liter, 6-cylinder engine and normal turbo pressure is significantly higher than what is realistic."
Gruß Christian
A6 BPP, Ex-A6 AKN (Gurke), Ex-Audi100 92 AAT (5Zyl.)


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Post09-08-2009, 17:42    Subject: Low LMM, Low Top Speed? Quote

Generally, or specifically referring to the RPM range around 3000-4000?
Because in the short term, it seems he's managing to achieve results, as you can see.


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mserge
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Post10-08-2009, 11:52    Subject: Low LMM, Low Top Speed? Quote

As I can see from the log here, this was a significant overshoot. You can see from the target value of 849 mg/cycle where the value should approximately be icon_wink.gif.
A4 Avant 2,5 tdi 110kw; AFB; BJ2000
4 neue Nockenwellen bei 135 tkm!!
neuer Turbo bei 200.000km
neue ESP bei 216.000km
verkauft mit 225000tkm
jetzt Renault Espace 2,0 dci 172 Initiale BJ2012
Clio 2 RS 170 PS BJ2003


Translated on 20-09-2026, 15:28.
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