WIV und die (unvorhersebaren) Folgen | Posts 16+

Okay, you've definitely piqued my curiosity now!

My AWX has a maintenance interval of 90,000 km for the air filter. The original one is still in there. I let my colleague, who's known for his heavy foot, try it out with some short bursts of acceleration. I couldn't notice any excessive soot. Okay, it's also just a Euro3 engine.

'I'll take on the diesel fuel consumption logging next week, comparing it to a 1Z. However, I think I'll be comparing apples and oranges here, as my old 1Z only had 90 horsepower without a turbo, while my beloved AWX has almost twice that power!'

Hi Jörg,


The cloud of black smoke was clearly visible in the rearview mirror. I didn't need to look outside to see it. I never experienced that with my previous car (a 1Z).
The Euro3 standard allows for higher levels of particulate matter (PM) emissions than the Euro4 standard.

Let's specify a "drive test," then we can compare the results (AXR - 1Z).

so, there was no smoke cloud. I didn't see anything in the rearview mirror, which is why it was from the outside!!!!

Please suggest something regarding the test drive!

Bertil wrote:

By the way, yesterday, for once , the AXR stopped working – no error codes stored! – The relay for power supply had bad solder joints. Somehow, I can't shake the feeling of a Monday morning, but perhaps the lawyers should deal with that now.

Relay 109 sends its greetings.

I hardly know any TDI drivers with cars from the years 1996-1999 whose relay doesn't fail sooner or later due to faulty solder joints. And what's great about it is that the power supply relay also provides power to the error memory. Therefore, there are no error entries. If you then go to the wrong workshop, they will search for the problem endlessly.
What drives me crazy is that there was no recall in this case.
That would have saved me the trouble of breaking down on the highway bridge.

I hope you can achieve something through your lawyer.
Keep us updated.

Let's talk about the air filter again. Do you actually clean (if present) the screen that is located in the intake duct on some VEP models (i.e., the part connecting the air filter to the headlight housing/air intake opening)? On my TDI VEP, this screen gets clogged after a few thousand kilometers, which causes a flap to open towards the engine compartment and draw in 'pre-filtered' warm air instead of cool air. This screen isn't even mentioned in the maintenance schedule, although it clogs up very quickly. Or have you removed it altogether, if it's present?

Just a quick note about the air filter. Do you actually clean (if available) the screen that is located on some VEP models in the intake channel (i.e., the part that connects the air filter to the headlight (intake opening))? In my TDI VEP, this screen gets clogged after just a few thousand kilometers, which causes a flap to open towards the engine compartment and draw in 'pre-filtered' warm air instead. This screen isn't even mentioned in the maintenance schedule, although it clogs up very quickly. Or have you removed it completely, if it exists?

If you remove the filter, all the dirt will end up in the airbox. That's probably not good for the mass airflow sensor (MAF).
And you can figure out the rest yourself, right? If it sucks in warm air from under the hood, it loses power, and the back pressure of the air in front of the car isn't being used to force air into the engine.

verschandeln it at the latest after 10,000 km... it always made my car happy!

Hi Tagessuppe,

Tagessuppe wrote:

Relay 109 sends greetings.

I would be more cautious with that label!
"On mine, the relay is unmarked (so it doesn't have anything printed on it like '109')! That's why I didn't refer to it that way."
At relay 109, the VAG workshop usually doesn't recognize it (most of the time).

@joergs

Quote:

make a suggestion regarding the test drive!!!!

Well, that's not so simple. How are you going to standardize the approach procedure?
My suggestion:
Find a flat stretch of road. Start in first gear without pressing the accelerator and let the vehicle roll for 2-3 seconds. This ensures that the electronics correctly readjust to idle speed. Then, abruptly accelerate to full throttle, reaching approximately 2000 or 2500 RPM. While logging data with VAG Com, record the fuel injection amounts, pedal position, and engine speed. The recording from the moment of full acceleration is important.
I've always done this test, and it produces a lot of smoke.

Does anyone have any other ideas?

@bertil

If no other suggestions come up, then I'll proceed with it like this!
However, it will be available at the earliest on Monday, as I have a long weekend starting tomorrow!

Hi there,

If I do a similar test with my wife's car (in first gear at idle and then full throttle), it will definitely cause the tires to spin. It also happens in second gear, depending on the road surface.

I've noticed that the car occasionally produces a lot of black smoke when starting, especially if it has been turned off for a while.
Could it be that the regulation of the PD elements doesn't function correctly at very low rotational speeds?

Regards,

Eike.

... some time ago, there was a discussion in this forum about Volkswagen discontinuing its use of particulate diesel (PD) technology because it would be difficult to meet future emission regulations with it.
I recently read in a specialist magazine that VW and Siemens have jointly founded a limited liability company (GmbH) to develop new PD (piezoelectric direct injection) elements, which are a combination of PD and piezo elements. The PD technology is used for high pressures, while the piezo element provides more precise fuel injection control. This technology is likely to be implemented starting in 2005.
Wait...

Regards,

Eike.

Hi,

eike wrote:

If I do a similar test with my wife's car (in first gear at idle and then full throttle), it will definitely cause the tires to spin. It also happens in second gear, depending on the road surface.

Does it not have ASR? I haven't tried it yet (the car is already back in the workshop ).

Quote:

I've noticed that the car occasionally emits a lot of black smoke when starting, especially if it has been turned off for a while. Could it be that the regulation of the PD elements doesn't function correctly at very low rotational speeds?

Why would the engine produce soot right after being turned off?
That's the same effect as I experienced with mine. After changing the filter, it got better.

@eike:
As far as I understand, these so-called "new" proportional valves are not a real innovation. It appears that the current solenoid valve has simply been replaced with a piezo valve. However, the mechanical and hydraulic design is practically identical.
The fundamental problem with direct injection (PD), namely that the injection pressure and pressure build-up rate are highly dependent on engine speed, certainly cannot be solved with this innovation.
A truly innovative solution would have been a piezo actuator functioning as a pumping element. This could achieve complete decoupling of the injection system from the crankshaft/camshaft, allowing for arbitrary control over pressure profiles and pressure build-up.

"In my opinion, the new piezo-valve controlled pressure divider elements are only a half-hearted solution born out of necessity to technically differentiate themselves from Bosch's pressure divider element (and avoid being seen as a copy)."

Regards,
Alex.

Hi,

donalexo wrote:

As far as I understand, these so-called "new" proportional valves are not a real innovation. It appears that the current solenoid valve has simply been replaced with a piezo valve. However, the mechanical and hydraulic design is practically identical.

Don't mix too many things up here!
"The piezo injectors are not yet used in the current 8V TDI engines, so you really can't form an opinion about this innovation."
"The piezo technology switches with significantly lower losses and even faster speeds, which should enable the realization of multiple injections, similar to what is achieved with common rail systems."

Quote:

The fundamental problem with direct injection (PD), namely that the injection pressure and pressure build-up rate are highly dependent on engine speed, certainly cannot be solved with this innovation.

"Two years ago, Bosch already implemented changes that allowed for a 40% increase in partial load pressure while simultaneously reducing driving forces by 25% (PD 1.1, used in the AXR engine)."

Quote:

A truly innovative solution would have been a piezo actuator used as a pumping element. This could achieve complete decoupling of the injection system from the crankshaft/camshaft, allowing for arbitrary control of pressure profiles and pressure build-up.

That's something even CR hasn't managed to do yet!

Quote:

"In my opinion, the new piezo-valve controlled pressure divider elements are only a half-hearted solution born out of necessity to technically differentiate themselves from Bosch's pressure divider element (and avoid being seen as a copy)."

Okay, I see it differently. I've seen the PD elements, and they are really tiny. This means they are less dependent on their installation position compared to the Bosch PD elements.

Hello Bertil,

The statement I provided simply represents my opinion regarding the "innovation level" of the piezo-polymer actuators. If you have a different opinion on that matter, please feel free to express it; I have no problem with that.

Quote:

Don't mix too many things up here!

That's why I haven't mixed things up at all; I was simply expressing my opinion!

Quote:

1. The piezo injectors are not yet used in the current 8V TDI engines, so you certainly cannot form an opinion about this innovation.

I am also aware of that. However, as a pre-development engineer, I have access to quite good and reliable sources of information, often long before the technology is ready for mass production.
Furthermore, I have already experimented with piezoelectric valves and actuators in other application areas.

Quote:

2. The piezo technology switches with significantly lower losses and even faster, which should make it possible to achieve multiple injections, similar to what is achieved with common rail (CR) systems.

There must be some advantages to switching to piezoelectric valves; otherwise, it wouldn't be worth the change.
Multiple injection serves primarily the following purposes:
1. Pre-injection to reduce noise by creating a gentler pressure increase.
2. Reduction of NOx emissions.
3. Post-injection for reducing particulate emissions.

However, it has a significant drawback: its efficiency decreases and fuel consumption increases! The process, through multiple injections, increasingly resembles the homogeneous charge compression ignition (HCCI) process and thus moves away from the more ideal stratified charge combustion process.

The combination of a 4-cylinder head and direct injection (DI) elements was likely only possible through a significant reduction in the size of the DI components. This alone might justify what I consider to be a relatively small innovation.

Quote:

Two years ago, there were already changes at Bosch, where the partial load pressure could be increased by 40%, while simultaneously reducing the driving forces by 25%.

Due to the system design, there is a mechanical coupling between the camshaft and the PD (positive displacement) elements. The system can certainly be well-tuned within a wide range by adjusting the cam geometry and the diameter/stroke ratio of the pump piston. However, there is a strong speed dependency of the injection pressure, which is much more significant compared to VP (variable pre-injection) systems. This could also explain the soot cloud I have often observed in vehicles with PD systems when they accelerate sharply from very low engine speeds.

Please don't misunderstand me. I don't think the PD technique is bad at all; in fact, quite the opposite. However, I believe people should also be aware of its "weaknesses."
And, in my opinion, a truly innovative feature starts exactly at this point. While reducing the structural space required and enabling multiple injections are certainly advancements, I consider the degree of innovation to be relatively low.

Regards,
Alex.

Hi,

Quote:

However, it has a significant drawback: its efficiency decreases and fuel consumption increases! The process, through multiple injections, increasingly resembles the homogeneous charge compression ignition (HCCI) process and thus moves away from the more ideal stratified charge combustion process.

All diesel engine developers, whether working with common rail (CR) or pump-injector (PD) systems, face the same problem: they must choose between a quiet engine operation and good fuel efficiency. To make matters worse, they also have to meet strict emission standards.

Quote:

Due to the system design, there is a mechanical coupling between the camshaft and the PD (piezoelectric direct injection) elements. The system can certainly be well-tuned within a wide range by adjusting the cam geometry and the diameter/stroke ratio of the pump piston. However, there is a strong speed dependence of the injection pressure, which is much more significant compared to conventional injectors. This could also explain the soot cloud that I have often observed in vehicles with PD systems when they accelerate strongly from very low engine speeds.

Absolutely! However, I've noticed that it also depends heavily on the condition of the air filter.

Quote:

Please don't misunderstand me. I don't think the PD technique is bad at all; in fact, quite the opposite. However, I believe people should also be aware of its "weaknesses." And, in my opinion, a truly innovative feature starts exactly at this point. While reducing the structural space required and enabling multiple injections are certainly advancements, I consider the degree of innovation to be relatively low.

I also view the PD (Plasma Direct) technology with great skepticism. In my opinion, CR (Cathode Ray) technology has just as many problems, but it can be implemented more cheaply. Even small improvements in technology advance research.

@Donalexo

Quote:

I am also aware of that. However, as a pre-development engineer, I have quite good and reliable sources of information, often long before the technology is ready for mass production.

Where do you work in the preliminary development phase, if I may ask? Or, which company do you work for in the early stages of product development?

Best regards,

Albrecht.