AGR Off Tuning: How to Check & Verify

Hello everyone,

Let's assume a chip tuner promises to disable the EGR system by modifying the engine control unit. I would then assume that he programs the desired characteristic curve of the EGR valve to be permanently open (does "open" actually correspond to 0 or 100 percent fresh air?). Are there any other possibilities here, or can I definitely check the tuner's work by monitoring the actual position of the valve using VCDS while driving?

By the way, 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 draws in at idle is approximately 450-500 mg/hour. If the measured air mass value is lower, it's likely that some exhaust gases are being drawn in. Of course, this statement only applies if nothing is defective.

Best regards, Rainer.

Hello Rainer,

"And how can I use this for testing? 'Normally' means that the EGR system is functioning correctly, which means that exhaust gases are always being drawn in/pushed in at idle, right?"

Furthermore, the mass airflow sensor (MAF) is located well before the EGR valve, specifically in the fresh air intake path between the air filter and the turbocharger. Its readings are completely independent of the EGR system... or am I misunderstanding something?

...or can I really determine whether the EGR valve is closed based on the actual air mass value, even though it should be open under otherwise identical conditions (oil temperature, air pressure, throttle position, etc.)?

Assuming I could switch between the original software and tuning software at any time (taking about 10 minutes to reflash), how would I identify a deactivated EGR system in the tuning software, specifically during idle or a "test drive"?

The value I mentioned is the air mass without EGR.

I would advise against doing anything here. A complete shutdown is relatively pointless for normal operation, and I also doubt that the usual suspects would put together something sensible for such a thing.

Best regards, Rainer.

kossmann wrote:

Are there any other options here, or could I definitely check the tuner's work by examining the actual valve position using VCDS while driving?

A deactivated EGR system significantly increases the engine's cold start time under low load conditions.

Therefore, if you measure the time it takes for the engine to warm up under known driving conditions and with a known ambient temperature, this time should be noticeably longer after the EGR modification.

For me, that was also the main reason why I didn't repeat my EGR experiments from my previous car in this one (although the auxiliary heater would have at least mitigated the time spent below +5°C ambient temperature).

I completely agree with Rainer and would not install an AGR system today. It costs money and time, it's a form of tax evasion, it harms the environment, causes the engine to run longer before reaching operating temperature, and has only very limited benefits (the intake passages don't clog up as much as they used to in older vehicles, because the amount of soot produced has been significantly reduced – otherwise, the DPF would also become clogged too quickly). In short: The disadvantages clearly outweigh the advantages.

Greetings.
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

To go back to the original question:

kossmann wrote:

I would now assume that he programmed the desired characteristic curve of the EGR valve to be permanently "closed" (are "closed" settings, meaning only "fresh air," actually 0 or 100 percent?). Are there any other possibilities here, or could I definitely check the tuner's work by examining the actual position of the valve using VCDS while driving?

Regarding the latter: Yes.
First, log the AGR using the appropriate diagnostic tool (for VEP and PD-TDI engines, it would be MWB 3). Let the engine idle for a few seconds when warm, then accelerate briskly from low RPM in each gear up to 4th. During acceleration, the TV display should show the "AGR closed" value.
If this value is constantly visible even at idle and during partial load cruising, it indicates that the EGR system has been deactivated by software.
The AGR (Automatic Gearbox Regulation) system's improper operation can be revealed by a constant, slight swaying or trembling of the television screen.

kossmann wrote:

Hello Rainer, and how can I use this for checking? Doesn't "normally" mean that with a properly functioning EGR system, exhaust gases are always being drawn in/pushed in at idle?

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

Quote:

Furthermore, the mass airflow sensor (MAF) is located quite far upstream of the EGR valve, specifically in the fresh air intake between the air filter and the turbocharger. Its readings are completely independent of the EGR system... or am I misunderstanding something?

Misunderstanding. The volume of exhaust gas being expelled prevents the intake of an equal volume of fresh air, which is why the example of 250 mg/h was given above.

For the specified engine code (MKB), a potentiometer for exhaust gas recirculation (EGR) – part number G212 – should already be integrated into the EGR valve. This potentiometer electronically reports the control range of the EGR and provides you with the information you're looking for directly and readily available.

Thank you very much for all the suggestions and comments.

Roger wrote:

For the mentioned engine control unit (ECU), a potentiometer for exhaust gas recirculation (EGR) G212 should already be integrated into the EGR valve, which electronically reports the control range of the EGR and provides you with the information you are looking for directly and without any extra effort.

Could you give me a quick hint on how to access that information using VCDS? I've already managed to get to the "AGR actual position" through the advanced measurement blocks of the MSG (I don't remember the exact name right now, but it was position 157 in the long list).

kossmann wrote:

Could you give me a quick hint on how to access that using VCDS? I've already accessed the AGR actual position (I don't have the exact name right now, but it was position 157 in the long list) through the advanced measurement blocks of the MSG.

Then you've found the measurement value, haven't you?
Select and observe, or log.

If that's the case, yes. I was just surprised that after the "tuning," the value still fluctuates around the area like it did before. I would expect to see a permanent 0% (or 100%???) reading here with the EGR deactivated. It's likely that in this case, nothing actually changed regarding the EGR.

You can probably assume that.