"Blow by" gases measure using VAG-COM?

Hello,

first: by 'blow by gases' I mean the exhaust gases that creep between the cylinder wall and the piston rings in the crankcase.

That's normal, it also happens with new engines, but the higher the wear and tear/lifespan, the higher this flow rate. A crack in the cylinder head can also lead to exhaust gases leaking into the camshaft chamber.

From the blow-by, the oil is expelled (cyclone/filter). These gases are then introduced into the intake duct, behind the air mass flow meter, and before the turbocharger (a little oil remains, so the entire intake path is oiled).

So, das bedeutet: Volumetric input to the mass flow meter => potential power loss.

I disconnected the hose, and the intake pipe is blocked (to prevent air leaks). Even at idle, there's an immense volume of air coming out from the engine side! If you seal the outlet with your thumb (at the top of the valve cover), a rapid overpressure develops, which causes the oil level indicator to pop out of its place...

Okay, it would be great to know what the 'blow by' flow rate is. It could be a real alternative to the unreliable compression test. And even more impactful.

We could potentially measure this: Use a VAG-COM, and have the engine run at idle. Then detach the fuel line from the valve cover, and IMMEDIATELY tighten it by hand.

Now, the 'blow by' gases are exiting into the open, and not into the intake manifold, and the mass airflow sensor should show a difference (more air, as the now missing blow-by current is now detected by the mass airflow sensor)

Okay, I'll only have the equipment in two weeks, and I'll post the results (hopefully at multiple speeds).

If you still have any ideas, then let's go! If it's truly getting, then you need so many comparative measurements from you as possible...

Greetings
Perwollf

_____________________________

The reason is that my vehicle (A4 B6 1.9TDI, AVB, all original) is not reaching its top speed. Even according to the speedometer, it is 10kmh lower. Because every possible error has been ruled out, such bold theories remain, and natural tolerance as the cause.

Specifically, full load and high RPM increase the blow-by volume.

Hello Perwollf,
"Should I use "Equipment" instead? Perhaps you should measure the boost pressure. It might be fluctuating." And, the final speed is dependent on several factors (tires, weight-equipment!, environmental influences, etc.).

lg robert

Why don't you just open the oil filler cap while the engine is running and check if there's a middle-sized storm coming out? I'm already claiming that the missing 10 kmh isn't due to a lack of compression. If that were the case, you might also experience other problems, such as poor starting behavior.

Hello.
The lack of engine performance almost certainly does not come from the escaping combustion pressure as you suspect. As long as the vehicle starts well when cold, the compression is also correct, and therefore, no performance loss is to be expected. Even vehicles that have cold starting problems due to too low compression usually still have their full engine performance. Simply perform a performance test and see how much power you need or how much RPM you are missing. The maximum power should be around 4000 1/min, I believe, for your vehicles. Has the cat already been checked? - This could be an error on their part???
Best regards - Rumpi.

Hello, thank you for the responses!

@LZ: The loading pressure is OK, I have already checked with LDA. The -10km/h speed reduction is unfortunately always reproducible on a flat road, regardless of whether it is winter or summer tires, temperature, etc.

@Marco: Removing the fuel cap (or oil level indicator) is only half the truth. A large portion of the gas is still being sucked through the crankcase ventilation into the turbocharger.

@Rumpi: ja, ich habe auch meine Kat misstrauisch gemacht. Aber ich weiß nicht, wie ich es überprüfen könnte, außer ohne die Kat eine Probefahrt zu machen... However, he doesn't actually use real tools, and the sight check is also okay.
I would prefer not to invest money in performance tests, as long as the problem is only -10km/h. That's just a theoretical problem...

In general, I didn't necessarily think about my performance issue, but rather purely technically about the blow-by volume. If I have something new, I will get in touch.

Wishing you a wonderful weekend!

Hello,

I'm not quite understanding your concern. KG Druck also measures the oil level using the dipstick. What's wrong with that? Just go there, throw a 5 Euro bill in the tip jar, and borrow the tool, or have the mechanic measure it. It only takes about 5 minutes. However, I would rather focus on finding the reason for the missing 10kmh...

Hello Marco,

If everything in the ventilation section between the KG (Katalysator) and the intake pipe is verschandeln and unobstructed (e.g., oil separator, hoses, etc.), then a significant KG (Katalysator) overpressure is unlikely, because the gases are immediately sucked into the turbocharger. Or?

Therefore, I would prefer to look for other methods that measure the flow of volume.

Greetings
Perwollf

Hi,

I was talking about the oil dipstick and not the KG ventilation!
Assuming you are attempting your aforementioned method, how or according to which conversion do you create the corresponding mBar value for the KG pressure from the LMM values? One should not rely on experience values in this method either, as each LMM reacts slightly differently. In my opinion, this is not a viable approach. But I am always happy to learn.

What could be wrong with Marcos method? It's the simplest way. Believe him. What you're trying to calculate and convert involves an enormous number of influencing variables, which would only provide a rough estimate. If you let the motor run and carefully turn off the filling nozzle, you'll know immediately. The pressure always takes the path of least resistance. Therefore, compare the KWG ventilation diameter with that of the oil filler opening.
This, in itself, provides a fairly conclusive result.

Hello everyone!

I must say, I don't think the idea of Perwoll is that bad.
However, I would like to point out that the difference (LMM value) must definitely be measured with the EGR system deactivated (mechanically closed), because otherwise you will not be able to detect any difference. The AGR is a control loop that regulates the programmed air mass value, and the disturbance variable of the blow-by volume is regulated

Okay, for measurement purposes, first temporarily disable the AGR (Air-Gas Ratio sensor) and then determine the air mass values for specific operating points. Subsequently, temporarily move the KGE outdoors (this is prohibited during operation, only for measurement purposes!) and ensure a good seal of the opening in the intake pipe.
Now, one should possibly be able to distinguish between a clamped KGE and a deactivated KGE.
I'm really looking forward to the results!

It only makes sense to discuss this once we have results here, to determine whether this measurement method is meaningful or not.
In a standard 1.9 TDI engine, the amount of fresh air entering the intake without the EGR system is approximately 470 mg/h. The key factor is the relationship between the amount of air bypassing and the amount of fresh air.

Greetings
Alex

Aha, und dann baut man bei jedem Fahrzeug den LMM ein, mit denen die Referenzwerte entstanden sind? Ich behaupte immer noch, dass diese Methode absolut ungenau und vor allem umständlich ist. But let's wait and see what happens.

EDIT: I also have to admit that an LMM also ages, which further distorts the results.

Marco wrote:

I acknowledge that an LMM also ages, which further distorts the results.

Yes, but differences between KGE series and KGR outdoor can also be measured :wink:even with aging LMMs.

Hello everyone,

I really don't want to offend anyone, and I appreciate every response. But I get the impression that donalexo was the first person to actually read and think about what I wrote. His objection regarding AGR is completely correct. The AGR isn't causing me any problems anymore (it has caused quite a mess in the intake manifold)

Many only focus on one point, and without thinking deeply. Then comes a short, simplified answer, see /viewtopic.php?t=6230
I am not a genius, and even if I may seem incomprehensible, the probability that the basic idea is completely nonsensical is not particularly high.

Marco asks:
'How or according to which conversion do you create the corresponding mBar value for the KG pressure from the LMM values?'

I would prefer not to create KG (Key Group) pressure values from LLM (Large Language Model) values. Instead, I hope to directly obtain the blowby volume from the differences in LLM values. There isn't a significant relative difference, or 'spuckt' anything else, then, as donalexo also writes, one can simply forget the whole thing.

Again: KG (Kaiser-Werke) documentation says very little about 'blow by' as long as the de-escalation in the ZK (Zentrale Krankenversicherung) system functions correctly. To accurately calculate the flow velocity from pressure, one needs to know the exact dimensions of the suction pipe on the KG-ZK-Oil Separator.

@Matthias says:
'If you start the motor and carefully turn off the filling nozzle while the wind is blowing against you, you'll know. The pressure always takes the path of least resistance. 'Therefore, compare the KWG ventilation diameter with that of the oil filler opening.'

Comparing diameters is quite rough. On the one hand, the ventilation benefits from the vacuum created before the compressor, behind the air filter, etc. On the other hand, the oil separator also acts as a restriction.

But let's assume that everything is coming out of the oil fuel nozzle. Estimating this flow rate is very subjective.


Greetings
Perwollf

Hello,


So, das bedeutet: Volumetric input to the mass flow meter => potential power loss.


And that is exactly what can be measured using the KGE pressure.
Furthermore, a diagnostic scan using VAG-COM also provides clarity regarding the aforementioned point. That's how you can see if the LMM values are within the tolerance range.

EDIT: I admit that I haven't yet recognized the practical benefits in this matter.

Hi!

Perlwolf's thoughts have given me another idea: BlowBy gas contains a relatively high proportion of exhaust gas. This exhaust gas is added to the intake air and therefore displaces some oxygen. BlowBy is essentially a mini-AGR.

To further increase the cylinder's fill level, one could directly direct the KGE into the open while under full load, thereby further raising the soot limit.

Okay, hier ist die Übersetzung:

'Please provide the following information: {NAME}, {EMAIL}, {PHONE_NUMBER}, {ADDRESS}, {PRODUCT_NAME}, {QUANTITY}, {PURCHASE_DATE}, {PAYMENT_METHOD}, {ORDER_ID}, {NOTES}.' And only for motorsport purposes, of course.

@perwollf

I'm not denying that your project will yield an interesting result, especially since you're clearly putting a lot of thought into it. I actually think it's a good idea. However, I read that you won't have the necessary equipment until two weeks from now, so I thought I'd offer my help. Normally, with a new engine (even one with less than 50,000 km), you can remove the oil filler cap and just need to be careful that the oil mist doesn't ruin everything. The escaping airflow is very minimal. I know that measuring this way is only subjective. I also know that this method won't lead to any specific numerical values. Also.
Personally, I have closed the AGR in my engine, and since I still had "too much oil mist" in the intake tract even after that, I installed a ProVent (a filter that separates the blow-by gases from the oil mist as much as possible by using the KWG ventilation). This modification allowed me to clearly see that there was likely a slight positive pressure there even in its original state. Of course, I know that a negative pressure will occur on the intake side, and I also believe that this will more than compensate for the resistance created in the pipe. However, if I were to open up a larger opening, it could potentially use this larger opening to vent. Also, man könnte auch einfach die KWG-Belüftung abstellen.

Well, what can I say, I thought I could suggest a quick, relatively simple method that wouldn't involve numbers.

I now fully understand the benefits of your project and consider it interesting, safe, and useful.

For my misunderstanding, I apologize.