AGR for AXR EU4: How to Implement It

Hi,

There are countless threads in the forum about exhaust gas recirculation (EGR). However, information regarding EGR for the AXR engine with EU4 emissions standards is quite scarce. Therefore, I am starting a new thread where I invite active discussions about this engine and its EGR system, taking into account the emission regulations. The topics of 'combustion chamber temperature' and 'soot formation' have already been discussed extensively elsewhere.

My questions/requests are:

1) In the event of an EGR valve failure, does a careless installation of a metal plate 'instead of' a gasket result in an error code being logged in the engine control unit (ECU)?
If so, is there a solution?

2) Can anyone post real or schematic images showing where a misinstalled metal plate might be found in an AXR engine?

'To my knowledge, disconnecting the EGR valve connector will create a permanent entry in the error memory. Is it possible to prevent this by connecting a resistor?'

4.) Who actually detected a 'defect' in the EGR system of the engine mentioned above? What are the consequences of this during the vehicle inspection (AU)?


Regards,
Sure, here is the translation of the text from German to English:

'Micha'

Regarding point 1: Of course, it will result in an error message if it's a Euro 4 D4 vehicle. It doesn't matter whether you disconnect the connector or install a metal plate; the indicator light on the instrument cluster will illuminate.

Here's the translation:

"If you've read all the posts, you know where the metal piece goes; it's essentially the same for all engines, whether they have water-cooled EGR or not. The order is likely something like this: EGR pipe gasket, metal plate gasket, intake manifold."

Here's the translation:

"Regarding point 3, you can probably only bypass the issue by implementing a very intelligent circuit that calculates the air mass as if the EGR valve were open, despite the actual EGR setting. A simple resistor won't solve the problem."

to 1a: YES.

to 1b: NO.

As for me, definitely not.

3: Yes.

'Regarding the emissions technician (Abgasmessmann): Depending on their intelligence and motivation... If the check engine light (MIL) is illuminated, there will be no emissions test (AU)!'


CU Gremlin.

Hi,

Just as an additional note: My technician examined the area in question very carefully with a flashlight, and it was clearly visible that he was looking for something that was either too thick or looked unusual.

At least he didn't seem disappointed when he realized that the car was absolutely fine.

Best regards,

January.

Bee wrote:

1.) Does a fault code appear in the engine control unit if, due to careless installation of a metal plate "instead of" a gasket, there is a defect in the EGR system? If so: Is there a solution?

You could try the high-adaptation of the air mass target value (see relevant articles on EGR systems).

With ASZ + ARL, it may be sufficient (with a bit of luck) that the remaining error does not result in any further errors being recorded.

While I'm skeptical about using an AXR (air-fuel ratio sensor) with a modified throttle to achieve higher EGR (exhaust gas recirculation) rates, it doesn't cost anything to try it myself...

ulf wrote:

You could try the high-adaptation of the air mass target value (see relevant articles on EGR systems). With ASZ + ARL, it may be sufficient (with a bit of luck) that the remaining error does not result in any further errors being recorded. While I'm skeptical about using an AXR with a throttle valve to achieve higher EGR rates, trying it out myself won't cost anything.

My AXR isn't enough.
However, this can vary from car to car and doesn't necessarily apply in general. The best approach is really to experiment and see what works.

By the way, there are now AXR Golfs (G4 station wagon) with OBD2 systems (mine doesn't have one yet), and it is absolutely impossible to disable the EGR valve on those vehicles. The emissions test is performed onboard these vehicles, and the system monitors the EGR rate within extremely narrow limits.
Since I don't yet have knowledge of the exact measurement method, I unfortunately can't provide any more information. How exactly exhaust emissions are monitored in OBD2 diesel vehicles is beyond my current understanding.

Bertil wrote:

By the way, there are now AXR Golfs (G4 station wagon) with OBD2 systems available (mine doesn't have one yet), and in those vehicles, it is absolutely impossible to disable the EGR system. The emissions test is performed onboard these vehicles, and it monitors the EGR rate within extremely narrow limits.

Hmm, here it is again, the dreaded OBD issue... on my registration document, item number 5 says: "D-D/OBD".
Is that something different than OBD2?

If not, I'm a little surprised that it's possible to prevent AGR (Active Grille Control) error messages with the adaptation trick in my ASZ engine (although it's an EU3 compliant one).
Or could it be that because the only control parameter is "valve opening" (instead of valve opening and throttle position as in the AXR), only relatively coarse exhaust gas dosages are possible, and therefore the error tolerance must be "huge" to prevent constant error messages during normal operation?

The vehicle registration document for my AXR (9N) with EU4 standard, dated April 2004, states 'D-D/OBD | 15'.

cu,
Curtis.

Hi,

'So, using a metal plate doesn't work with the AXR engine. I always get a MIL (Malfunction Indicator Lamp) error. However, increasing the mass airflow sensor value in adaptation channel 3 of the engine control unit, as described in the technical article, works perfectly. I don't know exactly how much it ultimately helps, but it's definitely better than before. Also, the intermittent idling fluctuations are completely gone.'

Best regards, Christian.

ulf wrote:

Bertil wrote: By the way, there are now AXR Golfs (G4 station wagon) with OBD2 systems available (mine doesn't have one yet), and in those cars, it is absolutely impossible to disable the AGR. The emissions test is performed onboard these vehicles, and it monitors the AGR rate within extremely narrow limits. Hmm, here it is again, the dreaded OBD issue... on my registration document, item number 5 says: "D-D/OBD". Is that something different than OBD2?

No!
That's exactly the problem.
"The entry "D-D/OBD" is missing from my vehicle's documentation, which means I only have a D4 classification instead of an EU4 one. However, in terms of emissions and taxes, they are essentially the same."
I need to perform a standard emissions test. With the EU4 vehicles, the measurement process now simply involves firing a shot at the engine and measuring the exhaust gases. No external equipment is needed anymore. Also, there's no need for excessive engine speeds.
In the future, authorities should be able to check emission limits during every vehicle inspection.

Quote:

If not, I'm a little surprised that it's possible to prevent AGR (Active Grille Regulation) error messages with the adaptation trick in my ASZ (though it's an EU3 engine). Or could it be that because the only control parameter is the "valve opening" (instead of valve opening and throttle position as in the AXR), only relatively coarse exhaust gas dosages are possible, and therefore the error tolerance must be "huge" to prevent constant error messages during normal operation?

I think the tolerance for errors is extremely low when it comes to EU4 vehicles. Therefore, a faulty DPF (Diesel Particulate Filter) will likely be noticed quite quickly.
The EGR system on the AXR engine is quite complex. It's controlled via the throttle valve, the EGR valve itself, and additionally through a controllable water cooling system. Previously, the EGR valve only had an open/close function; there were no other settings.

Hi,

My sticker says: 'EU4 / OBD II'.

How about that persistent error code? While it's resistant to being triggered repeatedly, can it be cleared using a VAG-Com device?
What could cause my EGR valve to fail in a way that wouldn't be detected during the next inspection?
Does the annual technical inspection (AU) for EU4 diesel vehicles still work without the vehicle being present?

Regards,
Sure, here is the translation of the text from German to English:

'Micha'

Bee wrote:

Hi, My sticker says: "EU4 / OBD II". How about that persistent error code? While it's resistant to being triggered repeatedly, can it be cleared using a VAG-Com device?

The error entry can be deleted.

Quote:

What could cause my EGR valve to fail in a way that wouldn't be detected during the next inspection?

Nochmal zu mitschreiben: .... NOTHING!
At least not that easily (see a few posts above).

Quote:

Does the annual technical inspection (AU) for EU4 diesel vehicles still work without the vehicle being present?

I don't want to waste any more words on this illegal method of "gaining AU."
Just to clarify: For EU 4 OBD2 vehicles (whether diesel or gasoline), the emissions test is generated with a complete data log extracted from the vehicle. This ensures that the emissions test is only compatible with the vehicle identified by the read-out chassis number.

Hi,

Here's the translation:

'Just as an additional note: My mechanic examined the area in question very carefully with a flashlight, and it was clearly visible that he was looking for something that was either too thick or looked unusual.'


My EGR valve is also broken. The pipe that connects the manifold to the intake manifold is cracked in my case. Even with a flexible part, you shouldn't move it too much. So I removed the part and sealed the manifold directly to the EGR component. Therefore, I should get a replacement pipe within 2 years...
So, be careful when decommissioning the EGR system: The pipe isn't very flexible.