Sprinkler Start Time Optimization: Software or Hardware?

Hi! In times of constant increased workload, the engine displacement tax, which is particularly discriminatory for Euro3 naturally aspirated diesel engines, really hurts, as SDI engines require a particularly large displacement to achieve the same power output. But even TDI and similar models with Euro3 or lower have to pay significantly, as they generally have no less displacement, but rather more horsepower, except for the 3L Lupo and Smart CDI.

The angry mechanic is inclined to go beyond simply fixing a faulty EGR valve, and instead, regardless of increased NOx emissions, adjust the injection timing from its compromise setting to an optimal point for fuel efficiency.

If I haven't missed anything, a diagnostic adapter for the admin can only be purchased for approximately €250 or more with the full VAG-COM version; the cheaper kit is only available with the shareware version, which is not suitable for adaptation. Since I don't know anyone who would want to share the adapter with me, the aforementioned price is simply astronomical for me.

Question: Are there any workshops that can adjust the injection timing for a 'five' (presumably referring to a specific engine setting) after an early adaptation?

Here's the translation:

Then there's the hardware-based intervention. In the simplest case, it involves an RC circuit connected in parallel with the NHG (negative hydrogen generator). In a more sophisticated approach, it uses a monostable flip-flop circuit with a constant delay. This offers an unlimited adjustment range and could even allow for experimentation with the injection start timing while driving (using a temporary potentiometer to adjust the time constant). The disadvantage is that a constant delay time results in a speed-dependent advance of the injection start angle, because the crank angle covered during that fixed time interval increases with increasing engine speed. At low and medium speeds, where fuel efficiency is most important, this hardware modification might have too little effect, or it could result in excessive advance at high speeds. Unless the delay time is made dependent on engine speed using a correction signal derived from the speed sensor, things become very empirical and complex.

That's precisely why I find the software-based intervention via an adaptation channel to be more elegant.

Question for you: What kind of potential savings can one realistically expect? I believe 'TDI industrial motors' mentions figures of 5 or 10%.

Is anyone in the Stuttgart area who has a full version of VAGCOM software?

Best regards,
Holger.

SeatArosa1.7SDI wrote:

Question for you: What kind of potential savings can one realistically expect? With "TDI industrial engines," I believe they mention figures of 5 or 10%.

Hi,

At the AFN (presumably a medical device or system), I did not achieve a clear reduction in [something] with a moderately advanced injection start time (10 seconds initially, and later adjusted).

AFAIK, the engines "suffer" (in terms of fuel consumption) the most due to injection timing in the lower load range. If you compensate for this by shifting the injection start time earlier, you may get excessively high peak pressures in the high load range -> a risk for the cylinder head gasket.

With a variable pump (VP), there's another way to achieve this by setting the pump to activate "too early."
This prevents the start of injection in the "high consumption" range from being adjusted to a later target value; instead, it remains at the earlier setpoint for more efficient operation. However, in the upper load range, the normal injection start values are still used.

You shouldn't overdo it, because if you do, the starter motor might stall or kick back when starting the engine, and there's a risk of the emergency mode activating during operation...

Hello,

I can only agree with Ulf here and would like to add something from my own experience.

The fuel-saving effect of a moderate early injection timing is present, but it will not be measurable in practice, meaning it's significantly smaller than 0.1 liters per 100 km. The engines are always optimized for emissions only within a very limited load range; beyond that, all engines are designed for fuel consumption/noise optimization. Therefore, only an early injection timing that is dependent on the operating point makes sense in this context.

By the way, consistently deactivating the EGR system is not always beneficial. Moderate EGR rates can provide up to a 3% fuel savings depending on the operating point. However, the negative impact on fuel consumption due to very high EGR rates (NOx emissions) often outweighs the benefits in many operating points, so that completely deactivating it can still result in a net fuel saving. Nevertheless, the environmental damage caused is significant and, in my opinion, does not justify the 2.50 Euro savings. But this is just my personal opinion.

Hi!

This prevents the start of injection in the 'filling range' from being adjusted to the later target value; instead, it remains 'more consumption-friendly' and stops at the control limit.

I've read that from you before. But does the EDC then switch to emergency mode due to the rule violation? If not, why not?

Moderate EGR rates can provide up to a 3% fuel consumption benefit, depending on the operating point.

I'm hearing this statement for the first time. Is there a logically sound, technical/physical explanation for it? Doesn't low-oxygen air generally reduce combustion efficiency?

However, the damage you are causing to your environment with that is significant, and in my opinion, it does not justify the savings of two euros and fifty cents.

It seems you're forgetting that an EGR system isn't a global emissions reduction device, but rather an emissions-shifting device. Without EGR, CO, HC, particulate matter, soot, and CO2 (due to fuel consumption benefits) would actually be reduced. The EGR is only necessary to force the overall ratio of pollutants to fit within the standardized emission regulations. But does that really help the environment?

I generally consider exhaust treatment methods that prevent fuel consumption optimization in engines, merely postpone the release of harmful substances, and have long-term side effects that increase fuel consumption to be unintelligent. This includes technologies like EGR (Exhaust Gas Recirculation) and diesel particulate filters.
I believe the three-way catalytic converter for gasoline engines is a success, despite a slight increase in fuel consumption, because it effectively reduces ALL pollutants at once. However, this is only possible with a homogeneous air-fuel mixture and a specific lambda value.

I believe that the SCR catalytic converter, which uses a reducing agent (urea solution) to remove any amount of NOx from the exhaust gas, is the right approach. This allows the engine to be optimized for fuel efficiency, which in turn reduces other pollutants, making a particulate filter unnecessary.
Unfortunately, Selective Catalytic Reduction (SCR) technology is only being introduced in commercial vehicles at this time.

Best regards,

I haven't been able to achieve any fuel savings from the various optimization attempts I've made on my Audi A4 (AFN). My A4 has a 42-liter auxiliary tank for biodiesel. During the week, I drive almost exactly 700 km round trip from home to work. At 6 liters per 100 km, it gets tight towards the end of the journey, especially on hills. Initially, I tried software adjustments, but the effect was negligible, less than 0.1 liters. Adjusting the injection start time earlier (which is already necessary when using biodiesel) didn't make a significant difference either. However, more anticipatory driving and optimizing my acceleration have helped me reduce fuel consumption by half a liter. I may never reach Ulf's claimed fuel economy of under 5 liters per 100 km, but at least I still enjoy driving, and I don't need to top up the biodiesel tank with another 5 or 10 liters in the middle of nowhere anymore.

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Moderate EGR rates can provide up to a 3% fuel consumption benefit, depending on the operating point.

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I am hearing this statement for the first time. Is there a logically comprehensible technical/physical explanation for it? Doesn't low-oxygen air generally reduce combustion efficiency?

Okay, here are just two key points: In AGR (Augmented Gas Recycling) systems, the efficiency of the high-pressure process is higher due to a higher average combustion temperature (which should not be confused with local peak temperatures, which decrease; this is why there's an NOx advantage), and there are low charge exchange losses. This topic is very interesting but also quite complex and cannot be fully answered in just a few lines. If you're interested, I can provide you with some sources from the technical literature.

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However, the damage you are causing to your environment with that is significant, and in my opinion, it does not justify the savings of two euros and fifty cents.

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You seem to forget that an EGR (Exhaust Gas Recirculation) system is not a global emissions reduction device, but rather an emissions-shifting device. Without EGR, CO, HC, particulate matter, soot, and CO2 (due to fuel consumption advantages) are actually reduced. The EGR system is only necessary so that the overall ratio of pollutants can be forced into the standardized emission regulations. Whether this really helps the environment? I generally consider exhaust treatment methods that prevent fuel consumption optimization in engines, merely postpone the release of harmful substances, and have long-term side effects that increase fuel consumption to be unintelligent. This includes technologies like EGR (Exhaust Gas Recirculation) and diesel particulate filters. I believe the three-way catalytic converter is a successful innovation for gasoline engines, despite a slight increase in fuel consumption, because it effectively reduces ALL pollutants at once. However, this is only possible with a homogeneous air-fuel mixture and a specific lambda value. I believe that the SCR catalytic converter, which uses a reducing agent (urea solution) to remove any amount of NOx from the exhaust gas, is the right approach. This allows the engine to be optimized for fuel efficiency, which in turn reduces other pollutants, making a particulate filter unnecessary. Unfortunately, the SCR technology is only being introduced in commercial vehicles at this time.

Dear SeatArosa1.7SDI,
Unfortunately, you've fallen for some rumors that I don't want to perpetuate here. Otherwise, every reader might feel compelled to remove or disable all emission-reducing components from their vehicle.
If you imagine how the EGR system works in a simple way, you can see that it only recirculates exhaust gases from the combustion air. This means that the burnt air and fuel are burned again. The most important effect of this is a reduction in the mass flow of exhaust gases; for example, with a 50% EGR rate, the amount of exhaust gases leaving the engine is reduced by half. This automatically leads to a drastic reduction in all components of pollutants, including soot. While it is undeniable that a "shift effect" occurs between NOx and soot/CO/HC at very high EGR rates, you have already significantly reduced most of the pollutant components due to the previously mentioned effect before reaching that limit.
Furthermore, only the dependence on NOx and particulate matter is discussed because increased levels of hydrocarbons (HC) and carbon monoxide (CO) resulting from EGR are completely converted by the oxidation catalyst in diesel engines.
I wouldn't dismiss the diesel particulate filter as being pointless. The carcinogenic effect of fine particles in diesel exhaust unfortunately has to be considered a reality, and that can't simply be brushed aside.
Of course, the conflict between fuel consumption, emissions, and engine noise remains, and one should really consider where they prioritize their focus.
Cutting-edge technologies like SCR systems are not a universal solution either, as they also come with drawbacks such as increased fuel consumption, and the potential for NOx reduction may not be significant enough to eliminate the need for EGR (Exhaust Gas Recirculation) and particulate filters.
In my opinion, we should largely abandon exhaust gas aftertreatment (i.e., modifying the exhaust gases after they are produced) and instead focus on internal engine modifications that prevent exhaust gases from being generated in the first place during combustion. However, this would move us further away from diesel engines and closer to FSI technology, which will take time.
I would also be happy to recommend some further reading material here.[/quote]

bafische wrote:

If you imagine how the EGR system works in a simple way, you can see that only exhaust gases from the combustion air are recirculated. This means that the burnt air and fuel are burned again. The most important effect of this is a reduction in the mass flow of exhaust gases; for example, if the EGR rate is 50%, the amount of exhaust gases leaving the engine is reduced by half. This automatically causes a drastic reduction in all components of pollutants, including soot. It is undeniable that a "shift effect" occurs between NOx and soot/CO/HC at very high EGR rates, but before you reach this limit, you have already significantly reduced most of the pollutant components due to the previously mentioned effect.

Hi Bavarian,

An interesting perspective.

Regarding the "automatic drastic reduction of all pollutant components," I must ask how this aligns with the practically unchanged fuel consumption in everyday use (with or without EGR).
Because if the mass flow rate of the diesel fuel – that is, the amount of diesel entering the engine as "raw exhaust material" – remains practically unchanged, then, in my opinion, the resulting mass flow rate of combustion products cannot be different either.

While the increased airflow without exhaust gas recirculation (EGR) increases the mass flow of exhaust gases, the mass fraction of (harmful) combustion products within it should remain unchanged due to the same fuel consumption; this means that the combustion products are discharged from the exhaust system in a more "diluted" state.

In my non-expert opinion, the AGR (Advanced Gas Recirculation) likely only has the effect of increasing the concentration of combustion products in the exhaust gas volume flow - in addition to the shift in individual pollutant fractions and the risk of carbon buildup in the intake manifold, which, I believe, is also not beneficial for the emission values.


Could you please comment on these thoughts?

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Regarding the "automatic drastic reduction of all pollutant components," I must ask how this aligns with the practically unchanged fuel consumption in everyday use (with or without EGR). Because if the consumption - that is, the mass flow of diesel fuel entering the engine as "raw material for exhaust gases" - doesn't practically change, then, in my opinion, the resulting mass flow of combustion products also cannot be anything other than what it is.

This leads us quite far afield. The mass fraction of regulated pollutants such as NOx/HC/CO/PM totals approximately 1% of the total exhaust mass flow, therefore there is no correlation between exhaust mass flow and fuel consumption with respect to EGR (Exhaust Gas Recirculation).

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While the increased airflow without EGR increases the mass flow of exhaust gases, the mass fraction of (harmful) combustion products contained within it should remain unchanged due to the same fuel consumption; that is, the combustion products exit the exhaust pipe more "diluted." With this, the AGR (from my non-expert perspective) can likely only have the effect of an increased concentration of combustion products in the exhaust gas volume flow - in addition to the shift in individual pollutant fractions and the risk of carbon buildup in the intake manifold, where the latter is probably not beneficial for the emission values, IMO.

This leads us further to the products of complete combustion, which are only CO2 and water. The exhaust gases we are considering here, such as NOx/HC, are products of incomplete combustion, which can be oxidized back into products of complete combustion during a secondary combustion process. This means that the undesirable components in the exhaust gas mass flow are oxidized into beneficial constituents. Therefore, while there may be an increased concentration in extreme cases, the overall emission is reduced.

I hope I was able to help you a little, but with this topic, it's often a matter of piecing things together bit by bit. At the latest when you start delving into the basics of diesel engine combustion, the connections become increasingly complex and can usually not be adequately explained in just two sentences.

By the way, a significant portion of the carbon buildup in the intake manifold is also caused by blow-by gases. While the EGR system also contributes to this, the disadvantages are truly negligible in practice because any deposited substances are burned again once they dissolve.
The excessive protrusion of the suction pipe is often a consequence of excessively high EGR rates at low ambient temperatures, which is usually caused by gradual failures (e.g., faulty sensors), inadequate maintenance (e.g., air filter), or improper calibration by the manufacturer.
Trotz allem: Die NOx Schadstoffbelastung liegt teilweise um den Faktor 50 !! höher wenn die AGR abgeschaltet wird, das ist ein Niveau von vor 30 Jahren - und da sollten wir uns sicher sein, das wir das nicht fördern sollten.

bafische wrote:

The mass fraction of regulated pollutants such as NOx/HC/CO/PM is a total of approximately 1% of the total exhaust mass flow, therefore there is no correlation between exhaust mass flow and consumption with respect to EGR (Exhaust Gas Recirculation). . . . "Our" exhaust gases, such as NOx/HC, are products of incomplete combustion and can be re-oxidized into products of complete combustion during a secondary combustion process. This means that the undesirable components in the exhaust gas mass flow are oxidized into more desirable constituents. Therefore, while the concentration may increase in extreme cases, the overall emission is reduced. I hope I was able to help you a little bit, but with this topic, it's all about building from the basics. At the very least, when you start dealing with the fundamentals of diesel engine combustion, the connections become increasingly complex and can usually not be adequately explained in just two sentences.

OK, trotzdem danke für Deine Erklärung, die mir sogar (auf meinem Niveau) verständlich ist

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By the way, the sludge buildup in the intake manifold is also largely caused by blow-by gases.

Logically, soot and oil mist combine to form this wonderful mixture .

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Die AGR hat zwar auch hier einen gehörigen Anteil, doch sind die Nachteile in der Praxis wirklich zu vernachlässigen, da angelagerte Stoffe wieder verbrannt werden, sobald sie sich gelöst haben.

If you replace "as soon as..." with "if they ever come loose again," that more accurately reflects the dilemma in practice.

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The NOx pollutant emissions can be up to 50 times higher when the EGR system is deactivated; this is a level from 30 years ago, and we should be certain that we are not promoting such practices.

Schön gesagt - aber wenn man sich die einschlägigen Problemberichte und Fotos über Saugrohrverschlammungen anschaut, denke ich, daß viele Fahrer das auch nicht fördern wollen, weil ihnen der störungsfreie Betrieb ihres Wagens wichtiger ist als die Zusammensetzung von 1% seiner Abgase . . .

The build-up of sludge in the intake passages after more than 150,000 kilometers and many years of operation is significant, and as far as I know from the industry, this has not been taken into account in the development process.
Sure, there are test benches and long-distance runners. But which manufacturer subjects its engines to a realistic testing process for years before they go into series production?

In my opinion, there's a significant difference between running a new engine for 'x' hours on a test stand and accumulating those 'x' hours over multiple winters with frequent cold starts.

Und zu Abgastechnischen Zulassung einer neuen Motor-Karossen KOmbination zaehlt bestimmt auch nicht deren Verhalten in 10 Jahren.

m;

Hmm, yes.

diese Kondensatbildung im Saugrohr ist wirklich ein Problem, aber bitte Leute - das ist kein genereller Zusammenhang wie AGR aktiv = Probleme, da Ölschlamm im Saugrohr, sonst würden ja alle Diesel PKW der letzten 10 Jahre, die nicht die AGR abgeklemmt haben irgendwann nicht mehr laufen - und das ist nicht so.
Here's the translation:

"For example, taxi services operate under the most demanding conditions for condensation formation (short distances, only city driving, a lot of idling), and they experienced problems with this for a long time. However, manufacturers learned from this and redesigned their intake systems."
(Regular driver long-distance tests are also part of the normal development process), and most taxis (including VW models) can reach 300,000 km without experiencing excessive carbon buildup in the intake manifolds.
Ausnahmen werden aber auch weiterhin die Regel bleiben und mir ist wohl bewusst, das gerade einige VAG-Motoren erhebliche Probleme damit haben. Deswegen kann ich "gebrannte Kinder" verstehen.
But what am I saying? Disconnecting the EGR valve is no longer possible with the very latest and upcoming engine designs because the OBDII monitoring system will trigger an error, and there's not much you can do about it, except through chip tuning. However, that's extremely difficult, expensive, and risky with EDC16 systems.
Unfortunately, I seem to be standing here with my opinion on lost ground, but I hope that I was still able to instill a small amount of "guilt" in you.

Übrigens, dieses mickrige 1% böses Abgas auf das die AGR Einfluss nimmt, ist das gleiche mickrige 1% böses Abgas, das ein ein Ottomotor ohne 3-Wege-Kat in die Umwelt entlässt. - nur mal um das Grössenverhältnis der Schadstofferhöhung zu verdeutlichen.

lieber Bafische,

If you imagine the way the EGR system works in a simple way, you can see that only exhaust gases from the combustion air are recirculated. This means that the burnt air and fuel are burned again. The most important effect of this is the reduction of the mass flow of exhaust gases; i.e., if the EGR rate is 50%, the amount of exhaust gases leaving the engine is only half as large.

I think there's a fundamental flaw in your thinking here.

Um eine bestimmte Motorleistung zu halten, muß eine bestimmte Menge an Kraftstoff verbrannt werden. Dies erfordert eine bestimmte Mindestmenge an Sauerstoff in der Ansaugluft-> Stöchiometrie.
The diesel engine operates with an excess of air. The engine power can only be maintained as the EGR rate increases, provided that...
The oxygen content theoretically corresponds to at least the amount necessary for the complete combustion of all injected fuel molecules. (I will not consider here that the combustion efficiency decreases with increasingly oxygen-poor air, and thus also the soot limit.)

wenn 50% AGR-Rate, ist die Masse an Abgasen die den Motor verlassen nur noch halb so gross

Du vergißt, daß die Menge an Abgas, die dem Auspuffvolumenstrom zunächst entzogen wird, nicht einfach verschwindet. Denn das

The burnt air and fuel are burned again.

is utter nonsense. The exhaust gas consists of a mixture of gases that, as a reaction partner for renewed oxidation, is essentially no longer available (approximately 3/4 N2, 1/4 CO2 plus residual O2, traces of CO, HC, NOx). This means that practically the entire recirculated exhaust gas leaves the engine without accomplishing anything and goes towards the exhaust system, where it either permanently leaves the engine or repeats the same process. In other words: EGR constantly pumps a portion of the exhaust gases in a loop}.

Now, let's get to the actual fallacy:

If the EGR rate is 50%, the amount of exhaust gases leaving the engine is only half as much. This automatically causes a drastic reduction in all pollutant components, including soot.

With a 50% EGR rate, the intake volume flow of fresh air would be reduced to half, which is initially correct. However, it is absurd to conclude that the volume flow of fuel-oxygen reaction products in the exhaust would also halve, because the same amount of fuel must be burned to achieve the same engine power, regardless of whether or not EGR is used. The difference is: with a 50% EGR rate, the remaining oxygen content in the resulting intake air must be utilized much more strongly to completely burn the same amount of fuel -> the residual oxygen content in the exhaust decreases (theoretically down to zero, practically impossible due to the lack of a homogeneous fuel-air mixture). To compensate for the decrease in the EGR rate, all other uninvolved atmospheric gases in the exhaust volume flow, which are simply pumped through the engine (apart from the fraction of N2 that is oxidized to NOx), such as N2, CO2, Argon, etc., decrease. The total volume flow through the engine decreases due to the EGR, but not the volume flow of exhaust gases in terms of reaction products of the fuel+oxygen reaction (CO2, H2O, CO, HC, soot). What decreases is only the volume flow of uninvolved gas, which has nothing to do with the absolute amount of reaction products in the exhaust (except for NOx).

Only the 1 Vol% of CO and hydrocarbons can theoretically be beneficially oxidized 'in a second attempt,' but even this consideration is highly questionable. 1% of flammable gases are far from forming a combustible mixture, as in a gasoline engine, together with the intake air, which, once locally ignited, would spontaneously ignite. Since the mixture is practically homogeneous, only the portions of the 1% gas have the chance to oxidize if they are directly adjacent to local ignition sources (the igniting fuel injectors) during the injection process. A large portion of the gases are in 'colder' air layers of the combustion chamber and will never ignite. So much for the myth of CO and HC being 'post-combusted.' (Soot does not ignite anyway).


low charge exchange losses.

Why are the charge exchange losses lower? The volumetric flow of exhaust gas remains constant with the external EGR system used by VAG-TDI (only the chemical composition of the exhaust gas varies). Only the suction losses caused by the air filter are reduced, because the EGR reduces the volumetric flow of unreacted gases (N2 and excess O2) that pass through the engine. However, this is negligible if the system is in good condition.

If you are interested, I can send you some sources from the professional literature.

Yes, I would be interested in seeing sources that support the arguments you put forward, which I find to be quite absurd.

Furthermore, one only speaks of the NOx and particulate matter dependence because increased HC and CO from EGR are completely converted by the oxidation catalyst in diesel engines.

Again wrong. The catalytic converter can oxidize a large portion of the HC and CO, but not everything. The effectiveness of the catalytic converter is directly linked to the amount of residual oxygen in the exhaust gas, and this amount is reduced by the EGR system.

The lower combustion efficiency due to the EGR (the same amount of fuel is burned in a gas mixture with a lower oxygen density -> however, unlike gasoline engines, diesel engines do not have a homogeneous mixture, but only a local one during the injection process -> therefore, a lower oxygen density has an even more negative effect) results in that the absolute amount of unburned or partially oxidized exhaust components (HC, CO, soot) is actually higher compared to operation without EGR. This is exacerbated by the fact that, to compensate for the power loss due to the lower combustion efficiency with EGR, even more fuel must be injected.
This doesn't change the fact that a portion of the exhaust gases is recirculated within the system. The un- and partially oxidized components in the exhaust remain largely unaffected by being recirculated through the engine for the reasons mentioned above. Due to the lower oxygen density, there is less oxygen available for the undesirable oxidation of nitrogen, and also lower local temperature peaks – this is the only advantage, and ultimately the sole purpose, of Exhaust Gas Recirculation (EGR).

Forward-looking technologies, such as the SCR system, are not a panacea either, as they also involve consumption disadvantages.

'How did you arrive at that statement? Unlike the EGR system, diesel particulate filter, and three-way catalytic converter, the SCR catalyst does not interfere with the operation of the gasoline engine at all. That is, the engine parameters and the SCR catalyst are completely independent processes. How do you then claim that the SCR system increases fuel consumption?'
If you look at the matter purely from a financial perspective and not in terms of engine efficiency, you might be right. The urea solution is an auxiliary fluid, and its consumption should account for approximately 10% of fuel consumption. However, it's roughly as cheap as a saline solution. If you add the costs of electricity and auxiliary fluids to the operating fuel costs, you probably have about 1% higher costs per 100 km.


The potential for NOx reduction is not so great that one could do without EGR and particulate filters.

We are talking about NOx reduction rates of over 70% and a significant decrease in CO, HC, and particulate matter. To additionally use EGR (Exhaust Gas Recirculation) plus a diesel particulate filter would be a foolish idea. Not without reason, engine developers are now finally able to drastically increase the compression ratio, which was previously limited by NOx emissions. (The oxidation of nitrogen increases significantly with increasing compression pressure). Therefore: Precisely because one wants to avoid EGR and DPF, one resorts to SCR (Selective Catalytic Reduction).

In my opinion, we should largely refrain from exhaust gas aftertreatment (i.e., influencing the exhaust gases after they are produced), and instead focus on internal engine measures that prevent exhaust gases from being generated in the first place during combustion - but then we would move further away from diesel engines.

Finally, I can agree with you! And I would like to add: If we're already talking about exhaust aftertreatment systems, they shouldn't negatively impact the engine's efficiency.

FSI und GDI haben übrigens ähnliche NOx-Probleme wie Diesel, da man hier bei bestimmten Betriebszuständen kein homogenes Gemisch mehr hat (Luftüberschuß!), wodurch die Lamdaregelung des 3-Wege-Kats nicht mehr funktioniert (zu wenig CO und HC und zu viel Rest-O2 zur Reduktion des NOx), daher auch hier AGR.

und: ich wollt Dich jetzt nicht persönlich angreifen, auch wenn ich Deine Thesen förmlich in der Luft zerissen habe

Gruß
Holger.

SeatArosa1.7SDI wrote:

ich wollt Dich jetzt nicht persönlich angreifen, auch wenn ich Deine Thesen förmlich in der Luft zerissen habe

Hi Holger,

Du bist aber schon haarscharf an der Grenze zu persönlichen Tiefschlägen, wenn Du sowas schreibst:

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Your theses, which I find absurd

.
Instead of "abstrus," something milder like "questionable" would have sufficed .

Bafische als AGR-Befürworter steht hier wohl tatsächlich auf verlorenem Posten, aber er argumentiert bisher insgesamt sachlich(er). Daher bitte ich Dich "vorsichtshaber", Dich seinem Stil anzupassen.

Deinen Frust kann ich verstehen, denn auch mir sind Fotos von zugeschlammten Ansaugkrümmern ein Greuel, wenn ich mir vorstelle, daß sowas auch in meinem Wagen wachsen könnte, solange die AGR nicht völlig plattgemacht ist.

However, personal attacks (which seem likely to happen soon) will certainly not solve the problem, but at best will lead to the abrupt termination of a discussion that I find very interesting, and whose technical level is quite rare here.
Und das wäre schade . . .

I didn't want to personally attack you right now, even though I essentially tore your arguments apart .
Hi Holger,

Du bist aber schon haarscharf an der Grenze zu persönlichen Tiefschlägen, wenn Du sowas schreibst:
Your theses, which I find absurd.
Instead of 'abstrus,' something milder like 'questionable' would have sufficed .

Aber persönliche Angriffe (bis dahin scheint es mir nicht mehr weit) lösen das Problem garantiert nicht, sondern führen höchstens zum 'heißen Abbruch' einer IMO sehr interessanten Diskussion, deren fachliches Niveau hier durchaus Seltenheitswert hat.
And that would be a shame...

I completely agree with Ulf.

Wäre zu schade, wenn diese interessante und fachliche Diskussion wegen eventueller persönlicher Angriffe ins Stocken gerät.

Bafische soll seine Meinung vertreten können, im Alleingang ist es nicht besonders leicht, aber er bleibt trotzdem höflich, deshalb Respekt, weiter so...

Hello,

If I have the chance, I'll share an interesting chart about the topic of agricultural subsidies.

Please remind me.

Best regards, Rainer.

Hello everyone,

It's great that this topic is resonating with so many people. Besides good performance, torque, and fuel consumption figures, the development of diesel engines has increasingly focused on acoustics and emissions – and that's just as interesting to me as the power curve. And if others are interested in that too, I think I'm in the right forum.

As you've all probably noticed, the issue of exhaust emissions is incredibly complex – it touches upon natural sciences like chemistry, physics, and mathematics, as well as the traditional fields of mechanical engineering and electrical engineering.

To explain fundamental relationships in a simple and understandable way, even for those without a scientific background, I have simplified some mechanisms related to AGR (Abgasrückführung) systems. Consequently, SEATArosa1/TDI was right to find many quotes that do not withstand scientific scrutiny. However, the conclusions drawn from this need to be re-examined, at least in relation to diesel engines for passenger cars.
You can see, by the rapidly increasing number of contributions, that the discussion has reached a depth that goes beyond the scope of this forum. Due to time constraints (I'm leaving early tomorrow morning, but "postponed" doesn't mean "canceled"), I won't be able to provide a comprehensive technical response to SEATArosa. However, if there is sufficient interest, I would be willing to comment on some sections in smaller pieces next week.
I'll try to find some literature on the topic. However, I need your help with this, as I'm not yet able to create a website myself. Perhaps one of your moderators could receive something from me via email and then post it here.
There's definitely still something for all of us to learn from that.

By the way, thank you for the encouragement.