Leistungsmangel / Rauchbegrenzung AVF | Posts 48+

You probably mean the software within the MSG, right?
I can't tell whether it's the original, but definitely nothing was changed during my time.
Is there a way to find this out, or do I need to install a different MSG module?

I need to replace the EGR valve because it's no longer working.
When idling, the air mass reading is 450 mg/H, which should be around 250 mg/H.
The EGR valve control setting is at 84%, which to me suggests that the EGR valve is closed.
But I took the metal plate out again and connected the wires.
Therefore, the valve is not working; the pressure transducer is defective.
So, I need a new one before the next technical inspection, right? Or do you think it will pass without it?

Regarding the legend:
If you hover the mouse cursor slightly above a line, it will display the name, value, and time. I usually remove this feature to make the chart a bit clearer and larger. But if you want to leave it on next time, that's no problem!


If you're also surprised by these values, what could be the cause? Could it be a leak in the pressure equalization device (PDE), faulty valves, or an excessively large nozzle opening?
Because, in my opinion (IMHO), a negative value indicates that the cylinder is producing too much power and is therefore being restricted, right?
So, the amount of fuel injected into that cylinder must be higher than in the other cylinders in order for it to achieve that performance.

Gilliearnie wrote:

You probably mean the software in the MSG, right? I can't tell whether it's the original, but definitely nothing was changed during my time. Can I find this out somehow, or do I need to install a different MSG?

This cannot be done with common household methods. If you have access to a (tuner) flashing tool, you could read out the software and send it to me, for example, so that I can compare it with the OEM factory software.
Otherwise, you would need to use a different MSG (WFS!), and try it out, or obtain log data from another vehicle with the same MSG.

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I need to replace the EGR valve because it is no longer working. When idling, the air mass reading is 450 mg/H, which should be around 250 mg/H. The EGR valve control setting is at 84%, which to me suggests that the EGR valve is closed. But I took the metal plate out again and connected the wires. Therefore -> The valve is not switching, the pressure transducer is defective.

Okay, I didn't review the logs for that.
It's possible that something is just stuck. With the angled hose removed, you could try gripping the valve stem with a pair of pliers and lifting it upwards against the closing force; perhaps you'll hear a click, and then it will start working normally again.
Is the exhaust path from the manifold to the EGR valve clear? We don't want a carbon buildup blocking it, because even an expensive new EGR valve won't work if there's an obstruction.

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So, I need a new one before the next TÜV inspection, right? Or do you think it will pass like that?

As long as there are no errors in the error memory and the "readiness" status is set to OK (if this is already checked on your car / depending on the year of manufacture), you might even be able to pass with a closed AGR valve.

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If these values also surprise you: What could it be then? A leaking PDE element or valves? Or is the nozzle opening too large? Because, IMHO, a negative value indicates that this cylinder is producing too much power and is therefore being throttled, right?

In principle, yes. However, if 3 cylinders are weak, they essentially force the one functioning cylinder into a negative state for no reason, because the sum of all cylinder data is always zero.

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Therefore, the amount of fuel injected into that cylinder would have to be higher than for other cylinders in order for it to achieve that performance.

Not necessarily, see above.

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It's not possible to do this with common household tools. If you have access to a (tuner) flashing tool, you could extract the software and send it to me, for example, so I can compare it with the original OEM software. Otherwise, you would need to use a different MSG (WFS!) and test it, or obtain log data from another vehicle with the same MSG.

Okay, so I unfortunately don't have access to a flashing tool...
Unfortunately, I don't have any measurement data from a comparable engine available right now. Also, I don't know anyone in my network who has the same engine.

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Okay, I haven't reviewed the logs yet. It's possible that something is just stuck. With the angle tube removed, you could try gripping the valve stem with a pair of pliers and lifting it upwards against the closing force; perhaps you'll hear a click, and then it will start working normally again. Is the exhaust path from the manifold to the EGR unit clear?

We don't want a carbon buildup blocking it, because even an expensive new EGR valve won't help if there is.

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When I removed the EGR valve to verschandeln it, I tried pushing it from underneath with a screwdriver. It wasn't that easy; it was quite stuck. The spring force made it difficult to push the valve down. But I will definitely look into the soot plug suggestion again.

As long as there are no error codes stored and the readiness status is set to OK (if this is already checked on your vehicle / depending on the year of manufacture), you should be able to pass with a closed EGR valve.

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I have one manufactured in October 2001, so it's one of the early models. It's not being monitored yet. Maybe I'll just try it and see what happens. The TÜV (German technical inspection) will be done at my friend's workshop anyway. If it doesn't work out, he can just replace it right away. I think that's the best option.

In principle, yes. However, if 3 cylinders are weak, they essentially force the one functioning cylinder into a negative state for no reason, because the sum of all cylinder data is always zero.}

Oh, but I thought it was more likely that a single cylinder would have a problem than that three cylinders (not necessarily related) would be leaking, for example.

Gilliearnie wrote:

Okay, so I unfortunately don't have access to a flashing tool... And I don't currently have any measurement data from a comparable engine either, unfortunately.

Also, I don't know anyone around me who has the same engine.

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Well, it's not a critical issue as long as the engine doesn't revert to that state of instability after the point indicated in the log data.

When I removed the EGR valve to verschandeln it, I tried pushing it from below with a screwdriver. It wasn't that easy; it was quite stuck, so overcoming the spring force made it difficult to push the valve.

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Yes, the spring has some considerable force. However, as long as the valve stem is reasonably smooth after overcoming the spring force, you don't have to forcefully break the closed valve every time, and the EGR cooler doesn't leak, I think there's no reason to replace the entire EGR unit.

Oh, but I thought it was more likely that a single cylinder would have a problem than that three cylinders (not necessarily adjacent) would be leaking, for example. } For instance, if the PDE of the strong cylinder was replaced by the previous owner, then 3 old ones and 1 new one are working together, presumably with better atomization. That could already provide an explanation.

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For example, if the PDE of the strong cylinder was replaced by the previous owner, then 3 old ones and 1 new one are working together, presumably with better atomization. This could already provide an explanation.

Yes, that's certainly a good question.
Is there a way to check this and find out?
Or can I rather disregard this for now and check again in six months to see if the values have changed?

PDE elements weren't necessarily the cheapest either...


When the car was at the workshop, the mechanic used a vacuum pump to apply suction to the AGR valve and said that it wasn't moving.
Therefore, I initially assumed that the AGR (Abgasrückführungssystem - exhaust gas recirculation system) was defective. (It just occurred to me while I was eating...).
I knew it was broken, but I also don't exactly remember why I know that anymore.

Gilliearnie wrote:

Quote: For example, if the PDE of the strong cylinder was replaced by the previous owner, then 3 old and 1 new one are working together, presumably with better atomization. This could already provide an explanation. Yes, that is certainly a good question. Is there a way to check this and find out? Or can you rather ignore that and check again in six months to see if the values have changed?

That's how I would do it.

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When the car was at the workshop, the mechanic used a pump to create vacuum pressure on the EGR valve and said that it didn't move. That's why I assumed the AGR valve was defective. (It just occurred to me while I was eating...). I knew it was broken, but I don't exactly remember why I know that anymore...

It's better not to trust any workshop for defect diagnoses if you can check the thing yourself.

Okay, then I'll leave it as it is for now.
I have saved values so that I can always find them again...

I've now sealed the AGR again with a plate.
And the two hoses from the EGR valve and the АК (presumably a Russian abbreviation for something like "automatic transmission") were disconnected and sealed.
I'm going to continue like this for now and see if I experience the loss of power again at some point.

But it's highly likely that it was the AK [likely referring to a specific person or organization].


Thank you all for your help, and I will let you know as soon as the error occurs again.

Hi there,
The AGR valve should be checkable with VCDS in idle mode (if the engine control unit supports it).
- Perform actuator diagnostics up to and including the EGR valve.
- Exit actuator diagnostics;
- Access measurement data blocks;
- In mode MWB 3, observe the switching of the duty cycle and the target and actual values of the air mass. The duty cycle and air mass should oscillate between their minimum and maximum values.
- then select "actuator diagnosis" again;
- Complete the actuator diagnosis (that's what the control module requires).
This is already a basic functional test of the AGR valve. Of course, it doesn't guarantee that the valve will close completely at higher engine speeds.
hg
Herbert.

Herbert wrote:

- Perform actuator diagnostics up to and including the EGR valve step. - Exit actuator diagnostics; - Access measurement data blocks; - In MWB 3, observe the switching of the duty cycle and the target and actual values of the air mass; the duty cycle and air mass should switch back and forth between min/max values.

Is it really possible to exit the actuator diagnosis without the MSG ending the back-and-forth switching?
I haven't specifically tried this yet, but it seems somewhat exotic: if you were to do something like this from the VTG actuator diagnostics and then try to start driving quickly, you would experience an extremely aggressive "camel driver" acceleration .

To observe the AGR function, I would normally access the diagnostic menu (MWB) number 3 and then select the basic settings. This will also open and close the AGR, and you can log the data.

You need to re-enter the actuator diagnosis mode, and continue and complete it.
The MSG remembers the status of the actuator diagnosis and resumes where it was previously interrupted. You cannot simply start the process without any prior setup.
It works with the fuel injector control unit; it's even described in the repair manual. I specifically tested it with the EGR valve, and I'm sure it also works with other actuators (although my Audi doesn't have any).
Best regards.
Herbert.

I'm experiencing the same symptoms and have tried everything.