Problem bei AGR Anpassung - UPDATE (unten) | Posts 32+

Hello,

I would recommend that you log some measurement data.
Perhaps a new level of understanding will then become clear.

I don't think it has anything to do with the gasket. I'm more inclined to think it's a faulty mass airflow sensor (MAF) or a pressure sensor in the intake manifold. I hope it's not the fuel pump that's defective.
otherwise it will be expensive. Best regards, Chris.

*dust off*

Hi,

I also checked out the adaptation process. Without the AGR (Exhaust Gas Recirculation) system, the car was becoming a bit too jerky in this cold weather lately. So, I quickly reactivated the AGR. The engine now runs much smoother - what a miracle . However, the slightly worse throttle response is only noticeable in a direct comparison.

Then I tried adjusting channel 3 of the MSG to find a compromise between knocking and carbon buildup in the intake manifold. The maximum accepted value for my ASZ engine is 33638. With this value, the target air mass at idle increases from 260 mg/H to 345 mg/H when the engine is warm, which has resulted in a reduction in the EGR idle duty cycle from approximately 65% to approximately 55%.

Two questions still come to mind.

- What does the "rule of thumb" reduction mean in terms of the mass flow rate of the recirculated exhaust gas? Does anyone have a rough estimate for that?
- Does the higher target value have an impact on the fuel injection quantity limitation, or are other side effects to be expected?

Roger wrote:

For my ASZ, a maximum value of 33638 is accepted. With this value, the target air mass at idle increases from 260 mg/H to 345 mg/H when the engine is warm, ... - What does the estimation of the reduction based on a rough calculation mean for the mass of the exhaust gas flow being redirected? Does anyone have a rough estimate for that?

It is actually possible to calculate this quite accurately (easily in a simulator, but more difficult while driving).

1. A test measurement with the EGR system deactivated will show the actual maximum intake air mass.

2. The difference between this value and the actual value when EGR is active represents the proportion of air that is replaced by exhaust gases .

Quote:

- Does the higher target value have an influence on the fuel injection quantity limitation

-?
AFAIK, only as long as the soot limit is at its lowest.

Quote:

or are there any other side effects to expect

?
I wouldn't know of any practically relevant solutions, besides a cleaner intake manifold .

Okay, then I'll check the mass readings in an old log file when the EGR is completely deactivated and calculate the difference.

Quote:

AFAIK only, as long as the soot limit is at its lowest

.
In other words, does the higher specified air mass flow rate change the soot limit curve, or does it remain the same?

Roger wrote:

In other words: does the higher specified air mass setpoint change anything about the position of the soot emission limit line? Or does it remain the same?

The soot map determines the maximum possible injection quantity for each engine speed and for each air mass / stroke.

When air is replaced by exhaust gases (meaning the mass airflow sensor reports a lower amount of air!), the corresponding lower limit is drawn from the map -> In my opinion, the map doesn't need to be shifted for this to happen.

THX!

Hello,
The LMM (Lambda Measuring Module) indicates the amount of 'fresh air mass' (oxygen) being supplied to the engine, and based on that, the amount of fuel that can be injected for complete combustion without producing soot can be determined.
Best regards,
Günther.

Sure, Günther.

"But I had manipulated the target value for the air mass in the engine control unit. The specific impact of that manipulation on the function of the soot map was the interesting point."
It has been clarified, thanks to Ulf .

Hello,

I adjusted the value on my vehicle (AVF, see signature) from 32768 to the maximum possible value of 33638. As a result, the AGR rate decreased from approximately 60% to around 50%. Would setting the value to 33768 (assuming the ECU accepts it) yield significantly more improvement?
Well, let's see what my modification brings. It would certainly be an illusion to say that the vehicle responds better. But after all, imagination is also a form of education .
I will try completely deactivating the AGR later. Let's see if it's even possible on my model year without generating any error messages, or does anyone know anything specific about this?

Best regards, Matthias.

matt wrote:

I changed the value on my vehicle (AVF, see signature) from 32768 to the maximum possible value of 33638. As a result, the AGR rate decreased from approximately 60% to approximately 50%.

Hi,

Where do you get the value for the AGR rate? As far as I know, the AGR rate is, by definition, the (volume) ratio of fresh air to exhaust gases, and it cannot be explicitly read out anywhere using VAGCOM.

The percentage value in field 4 of the MWB 3 is only the duty cycle for controlling the EGR solenoid valve and generally does not indicate the actual EGR rate!

The amount of exhaust gas (mass) entering can be seen by looking at the air mass, especially when considering the air mass without the EGR system.

Sure, here's the translation:

"For example, with the default setting for MWB 3."

Malte1408 wrote:

The amount of exhaust gas (mass) entering can be seen by looking at the air mass, especially if you consider the air mass without any EGR (Exhaust Gas Recirculation). For example, with the default setting MWB 3

.
Okay. With that, you can also (albeit somewhat complicatedly) calculate the AGR (Average Gross Revenue) rate.

Okay, I didn't know that. You never stop learning.
So, the measured air mass increased from approximately 240 mg/hour to 330 mg/cycle due to the change. The measurement was taken at idle.
What would the air mass be if the AGR (Abgasrückführung) system were completely disabled? I have a general understanding of what happens in theory, but it's only qualitative knowledge. Unfortunately, I don't know what AGR rate a TDI engine operates at in the partial load range . Consequently, I can't estimate the change caused by my modification in the MSG (Motor Steuergerät) .
Best regards, Matthias.

matt wrote:

What would the air mass be if the EGR system were completely disabled?

Approximately 450 mg/h in the LL (likely referring to a specific location or context).

Okay, so the AGR rate was reduced from approximately 50% to about half. Well, let's see if we'll be able to notice a difference.

Best regards, Matthias.