Meaning of the Air Mass Standard Value?

Hello,

Since our Ibiza now has over 30,000 km, I decided to perform a few test runs (full throttle) to estimate the remaining lifespan of the O2 sensor.

Result: From approximately 3500 rpm, the LMM actual value falls below the target value of a constant 850 mg.
At 3738 rpm (Pmax at 3750), the value is still 815 mg, and at 4179 rpm, it's only 765 mg. Around ~4200, despite full throttle, the boost pressure will be reduced.

However, the torque limits present a different picture: the torque limit of approximately 4200 rpm is the lowest value, with a distance of around 2 mg to the soot limit.

That means, in turn, that a new LMM would, at best, further raise the torque limit beyond the existing limit – so, in terms of performance, it would be useless, because only the lowest limit value is always applied.

In terms of LMM (Left-Hand Muffler) replacement, it will likely only be necessary when the soot restriction (when the correct boost pressure, unobstructed air and exhaust paths, etc.) reaches its lowest value - or have I misunderstood something?
"However, I have often read here that one should replace the LMM if the actual value is below the target value..."

What exactly
And what is the meaning of the calculated LMM setpoint value (besides being a target value for the AGR control)?

Hi Ulf,

>30000? My car now has 39,000... so this effect might have already started, although I haven't noticed any performance loss yet.

The boost pressure drops below 4000 even under full load, which I tested on the highway a few months ago with the LDA. It maintains around 1000 mBar in 5th gear up to 4000, after which it gradually decreases and reaches approximately 900 mBar at a speed of 210 (around 4400 RPM). I, however, believe that this is a deliberate and intended throttling, in order to prevent the charger from being overloaded.

If I have more time again (my girlfriend had to go to the hospital unexpectedly), I will try to make measurement trips, if I can manage to get the voltage converter to work.

Best regards,

Jan

I can still remember the discussion about the DC-LMM very well. There was a diagram to be seen. It was nice to see that with the original LMM, the air mass decreased extremely at almost exactly 3500 rpm. And that, as Jan also wrote, could be a certain protective function of the motor-stage, which regulates the intake pressure.

Hi,

The boost pressure is being reduced.

Here's a KF from a 1Z

Greetings

so, that should explain the intrusion of air mass.

as I see it, the reduction in loading pressure for the PDs is also greater than that for the VEPs. This probably also contributes to the sluggishness in the upper speed range...

Hi everyone,

It was really just a side issue regarding the boost pressure!

The main question is, when should an LMM be replaced:
Even when the LMM-Is falls significantly below the target value at full throttle,
or only when the soot reduction reaches its lowest value?

I'm betting on the latter and would accordingly modify the LMM article - but before that, I wanted to hear some additional opinions.

The main question is, when should an LMM be replaced:
Even when the LMM-Is falls significantly below the target value at full throttle,
or only when the soot reduction reaches its lowest value?


Whether the LMM actually achieves its goals or not is, in essence, irrelevant as long as it doesn't incur any costs. And performance only kicks in when the fuel injection volume reaches the specified limit.

So, I would only switch to the LMM in the last case.

Greetings
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