A5 2.7TDI schlechte Leistung bzw. Beschleunigung LMM /AGR? | Posts 32+

I'm not just making this up out of boredom or because I'm looking for someone to write with.

I found your statements on that matter a little...

I just finished removing the intake manifold. I'll be sure to get back to you with my results once everything is put back together.

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Ich saug mir das doch nicht aus den Fingern, nur weil mir langweilig ist und ich jemanden zum schreiben suche.

Kann sein, kann aber auch nicht sein. Gab es dennoch in der Vergangenheit - auch völlig unabhängig von Foren - oft...

As I mentioned, the values in the latest logs appear completely normal. That's also why I cross-referenced them with the measured lambda value from the sensor. If this measured value is higher than the value calculated based on air mass/fuel injection quantity, then less fuel is actually injected than what the engine control unit thinks.
For example, the injectors may be clogged with carbon deposits, or the fuel temperature/fuel pressure readings may be inaccurate.

Air mass sensor target value, for EDC17 control unit in a Volkswagen Audi Skoda Seat (VAG) 3.0 TDI engine, software part number 8K0907401F.

There is no air mass control system operating outside of the low-load range.
Consequently, it's pointless to discuss it further. If you can prove the opposite is true for your control unit, I'd be happy to be convinced.

If I may add something else: the target value of 1200 mg/hub seems strange because it also appears at relatively low speeds and with limited emissions.
Above a certain load or engine speed, the EGR valve closes, and the mass airflow sensor (MAF) reading shows a fixed value, which is not used as a reference for control. Whether it reads 1200 or 1000 seems irrelevant; it's a fixed value, in my case, for example, 950. As far as I can see, the air mass is determined by the boost pressure and EGR rate, rather than being directly controlled.
Okay, let's do the measurements using the mass airflow sensor, oxygen sensor, and lambda readings. That should give us more information.
hg
Herbert.

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Wenn ich nochmal was dazu anmerken darf: die 1200 mg/hub Sollwert scheinen deshalb merkwürdig, weil sie auch bei recht niedriger Drehzahl und begrenzter EM auftauchen.

Perhaps he picked up the wrong value in the extended measurement blocks; you can usually tell quickly if, with active EGR control (the engine only sputters briefly at idle), the target value is still so high instead of the expected 220-300 mg/H.

Hello,

Here is a log with the suggested measurement values and pictures of the exhaust manifold/turbocharger (temperature sensor).
Unfortunately, I only got around to it today.

Thank you. For example, the value for the lambda ratio at 3000 rpm is 1.501 on a logarithmic scale.
Computationally, the result would be: (1042 mg/H / 50.64 mg/H) / 14.5 = 1.42.

That would indeed be an indication of insufficient fuel injection. At least, if the air mass is being measured correctly...

I would try mounting the sensor on the back of the vehicle and attempt to obtain data logs for parameters like engine speed (RPM), mass airflow, average fuel injection volume, and lambda value from a similar vehicle. This way, you could determine whether your measured lambda value is accurate or not.

Here's what you can do right now: Check the fuel temperature reading for plausibility, and also verify that the engine control unit is receiving a correct coolant temperature and charge air temperature (the latter should already be considered, but you never know what assumptions were made in the application).

Best regards, Rainer.

I think I just found the error! Edit admin: You don't have.

The temperature at sensor G83, located at the outlet of the intercooler (EGR cooling pipe), is only around 25°C (the target value according to VCDS is 90°C).
"When I unplug the sensor (which is reading 100°C), the radiator fan immediately turns on, and the engine runs much better under full load."
The temperature at the radiator pipe corresponds to the sensor value of approximately 25°C when the connector is plugged in.

It can't be the sensor, right?
If I disconnect the sensor connector while the ignition is on, the pump for the EGR cooler runs.

Attached are the logs again, with a temperature of 100°C.

It is definitely a fact that he performs very well without the G83.

Then you should compare the values from G83 (while running) to the other sensors. However, does the engine normally reach a coolant temperature of around 90°C?

Yes, all the other values are correct.
Only the temperature of the G83 coolant outlet reaches a maximum of 35-40°C during extended driving.

Weird... well, the radiator does cool things down, which is a good thing, right? Otherwise, it would be bad.

Is the difference in performance really measurable? Could you do some KPower measurements with and without [the modification/item]? The absolute value of the power measurement (i.e., the precise weight) isn't that important, as it's only about the comparison. Important: Be sure to read the instructions for KPower and group the measured values + use Turbo!


Best regards, Rainer.