"AGR off" Tuning - How to check

Hello everyone,

let's assume a chip tuner promises a customer an "AGR off," meaning deactivation of the AGR valve in the engine control unit. I would then assume that he programs the "target" characteristic of the AGR valve to be permanently "off" (i.e., only "fresh air") – are "off" (i.e., only "fresh air") actually 0 or 100 percent? Are there any other possibilities, or could I definitely check the tuner's work by monitoring the actual position of the valve via VCDS during operation?

Incidentally, it would be a 2.0 TDI engine from an Audi Q3 (engine code CFGC).

Hello,

the normal air mass that a 1.9 or 2.0 TDI engine sucks in at idle is approximately 450 - 500mg/h. If the air mass value in the measurement block is lower, then some exhaust gases are likely being sucked in. This statement, of course, only applies if nothing is defective.

Best regards, Rainer

Hello Rainer,

and how can I use this for verification? "Normally" means that the AGR is functioning normally, i.e. exhaust gases are always sucked/pushed in at idle, or?

Furthermore, the O2 sensor is located quite far in front of the AGR, namely in the fresh air intake between the air filter and the turbo. Its values are therefore completely independent of the AGR... or am I misunderstanding something?

... or can I really check if the AGR is closed based on the mass airflow (MAF) IST value, even though it would actually be open - under otherwise identical conditions (oil temperature, air pressure, throttle position, ...)?

To put it another way: Suppose I could switch between original software and tuning software at any time (~10 minutes to flash) - how would I recognize a deactivated AGR in the tuning software (idle or "test drive")?

The value I mentioned is the air mass without AGR.

I advise against turning anything here. A complete shutdown is relatively pointless for normal operation, and I also doubt that the usual suspects would be able to come up with anything useful.

Best regards, Rainer

kossmann hat folgendes geschrieben:

Are there any other options here, or could I definitely check the tuner's work while driving by verifying the valve's current state with VCDS?

A disabled AGR significantly extends the engine's idle time at low load.

Therefore, if you measure the time until the engine warms up with a known driving profile and ambient temperature, this time should be noticeably longer after the AGR modification.

This was also the main reason why I didn't repeat my AGR experiments from the previous vehicle on the current one (although the auxiliary heater would have at least significantly compensated for the time below +5°C AT).

I completely agree with Rainer and would not recommend installing an AGR (Exhaust Gas Recirculation) system today. It costs money and time, is illegal, harms the environment, causes the engine to run longer and cooler, and provides only very minimal benefits. (Modern intake systems no longer become as clogged as they did in older vehicles, as the amount of exhaust fumes produced has also been significantly reduced (otherwise the DPF would clog too quickly). In short: The disadvantages far outweigh the benefits.

Best regards,
Guste

To return to the original question:

kossmann hat folgendes geschrieben:

I would now assume that he has programmed the AGR valve's "target" characteristic for continuous operation (are "continuous" (i.e., only "fresh air") actually 0 or 100 percent?). Are there any other possibilities here, or could I definitely check the tuner's work on the valve's actual position via VCDS while driving?

To the last point: Yes.
First, log the AGR valve's MWB (for VEP and PD-TDIs, it would be MWB 3): A few seconds of idle at a warm engine, then accelerate briskly into 4th gear from the rev range. During the accelerations, the TV shows the AGR closed value.
If this value is also constantly visible during idle and partial load, the AGR is deactivated by software.
The AGR control operation reveals itself through a constant slight oscillation/trembling of the TV.

kossmann hat folgendes geschrieben:

Hello Rainer, and how can I use this for verification? "Normally," the AGR should always be functioning normally, meaning that exhaust gases are always sucked/pushed in at idle, or?

No, not always. After a certain period of idling, the valve closes. On a 1.9 ASZ (EU3), the air mass at idle always fluctuated between 250 (AGR on) and 450mg/H (AGR off).

Zitat:

Furthermore, the LMM is located quite far from the AGR, specifically in the fresh air duct between the air filter and the turbocharger. Its values are therefore completely independent of the AGR... or am I misunderstanding something?

Misunderstanding. The volume of the exhaust gas prevents the intake of the same volume of fresh air, which is why the above-mentioned 250mg/h was given as an example.

With the specified MKB, a potentiometer for EGR (Exhaust Gas Recirculation) G212 should already be integrated in the AGR valve, which electronically transmits the valve travel and provides you with the desired information directly and at your doorstep.

Thank you for all the helpful tips and notes.

Roger hat folgendes geschrieben:

In this case, a potentiometer for the EGR valve (G212) should already be integrated in the AGR valve, which electronically transmits the valve travel and provides you with the information you are looking for directly and at your doorstep.

Could you give me a quick rundown on how to access those extended measurement blocks of the MSG via VCDS? I've already found the AGR IST value (I don't have the exact name/position number in mind, but it was position 157 on the long list),

kossmann hat folgendes geschrieben:

Could you briefly help me understand how to access the relevant data using VCDS? I've already found the AGR IST value (I don't have the exact name in mind, but it was position 157 on the long list) through the extended measuring block of the MSG.

Then did you find the value? Select and observe/log.

If it is this, yes. I was just wondering why, after the "tuning," the value still fluctuated around the same range as before. I would expect it to be permanently 0% (or 100% ???) when the AGR is disabled. Probably, nothing was actually changed in this case.

You can probably rely on that.