Deactivate AGR with Switch? Possible? | Posts 16+

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Okay, and now there's the AGR (Abgasrückführung) system. When the engine is cold... "If it works, it should keep the hot exhaust gases within the engine." allow. When it's hot, I would prefer to switch back to the AGR (automatic climate control). disable. to prevent the intake passages from becoming clogged.

Let me dust off this old thread because I've been giving it some thought.
I liked it or had something similar before.

Keep the AGR valve active until the engine reaches operating temperature (to help it warm up faster and protect the engine in winter), then deactivate it to prevent excessive buildup of deposits inside.
I'm not really a fan of connecting to any glow plug signals.
because the engine is not yet warm.
A simple manual switch would suffice, allowing me to activate the EGR system with a button press.
could be deactivated (e.g., if the engine finally warms up in winter).

I have only read about mechanical deactivation solutions so far.
That is, disconnect the vacuum hose and seal it off, or install a metal plate.

The question is how to electrically control the EGR valve – that would be beneficial for...
A solution that also relies on the glow plug signal is required.

I have a plug-in hybrid electric vehicle (PHEV - EU3 standard) and I always alternate between driving approximately 6 km in short distances and 60 km in long distances.
"My primary concern is protecting the engine. If deactivating the EGR system via a switch isn't possible, would it be more gentle on the engine to keep the EGR active, especially during winter when there's frost?"

Best regards,
gromit

Hello.

Since the AGR (Abgasrückführung) is controlled by vacuum, one could implement the switching using a solenoid valve. How to best wire that up, I have no idea. The simplest solution would be a switch, but it could also be time-controlled or temperature-controlled.

Best regards!

My primary goal is to protect the engine.

I keep wondering what exactly is supposed to be saved here. The warm-up phase is the period when the EGR system is completely pointless and even harmful. At this time, the exhaust gases contain particularly high levels of particulate matter due to incomplete combustion, and the intake passages are especially prone to being clogged with soot deposits. A large amount of sludge condenses on the extremely cold surfaces of the intake manifold, which is abundantly supplied.
Increasing the compression end temperature with hot exhaust gases doesn't necessarily improve combustion. In fact, the exhaust gases reduce the oxygen content of the intake air, which hinders complete combustion. Furthermore, the glow plug serves as the ignition source, unless the compression end temperature is already high enough for spontaneous ignition. As far as I recall, the EGR system is even deactivated by default during cold starts to prevent this, until a certain operating temperature is reached (because NOx tends to form more in engines that are at operating temperature and have a correspondingly high compression end temperature and short spark advance).

Therefore, I would advise against it because it's not effective. There are many methods to actually support combustion during the cold start phase:

- Electric engine heater controlled by a timer (a very cheap solution).
- Auxiliary heater (more expensive, but doesn't require a power outlet).
- 'Fan' for the intake air, which, when powered by a 300W alternator load, warms the intake air by a few degrees and also increases the engine's base load.
- Inject oxygen from the Torinister welding machine into the intake air. This should also be very helpful for the cold start process.
- Before a cold start, inject a generous amount of oxygen into the intake manifold using a device consisting of an oxygen tank, propane burner, and heat exchanger. This way, starting the engine even in Novosibirsk at -60°C will not be a problem.
- and of course: use high-quality motor oil with a wide viscosity range, such as 0W or 5W oils, preferably fully synthetic.

Okay, and finally: Don't do a gradual warm-up; instead, start with a relatively high load and low to medium RPMs to quickly warm up the engine. Ideally, you would have a long stretch with a slight incline for the first few kilometers. Or a route with a constant speed of 90 km/h. Unfortunately, you can't always choose your route.

And one more thing: Apparently, Shell V-Power has a higher cetane number, although I haven't tested it myself. So, if you're really concerned, you could try it in very cold weather, provided it's financially feasible.

Okay, I think the package of measures is sufficiently comprehensive .

@SeatArosa1.7SDI

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I keep wondering what exactly is supposed to be saved or preserved here. The cold start phase is the phase during which the EGR system... sinnlosesten und schädlichsten überhaupt ist. DThe exhaust fumes. they then contain a particularly large number of particles because of the... incomplete combustion, and the intake passages are currently being... dann besonders heftig mit der Rußpampe zugeschlonzt. To: Condensation occurs particularly heavily on the cold intake manifold walls. Sludge, which is produced in abundance. The compression end temperature can be influenced by hot exhaust gases. increased, it doesn't necessarily mean that you are increasing the combustion. improved, because the exhaust fumes contaminate the intake air. oxygen-deficient, which hinders complete combustion. and it's detrimental. And the glow plug serves as the ignition source anyway. provided that the compression end temperature is not yet sufficient for... Self-ignition.

To the best of my knowledge:
Cold engine - increased wear and tear.
Warm engine operation - minimal wear.
That is to say, the faster the engine warms up, the less wear and tear it experiences.

According to your considerations:
Better verschandeln combustion but longer warm-up phase - reduced wear and tear.

I don't quite understand that. While cleaner combustion is definitely better, it's not...
that the engine takes significantly longer to warm up.

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If I remember correctly, that is why... AGR is even deactivated as standard by the EDC during cold start, until... "There is a certain amount of heat generated (and NOx is produced)." tendentially occurs more often with a warm engine, and accordingly... high compression ratio, high exhaust gas temperature, and short ignition delay).

A disadvantage is that it takes significantly longer for the engine to reach operating temperature when the EGR system is deactivated.
If the EDC were to deactivate the AGR (Abgasrückführung) during cold starts, the engine would always warm up at the same rate.
Whether it's with or without a metal plate in the EGR system, it's effectively not the case.

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I would therefore advise against it, because it's pointless.

In other words, from your perspective, it's better to completely disable the EGR system (even in winter), correct?

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It. There are many methods to improve combustion. How can we truly support the initial phase? - Electric immersion heater controlled by a timer (very inexpensive). Solution)

Unfortunately, I don't have a power outlet at my parking spot for the lamp post .

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- Auxiliary heater (more expensive, but doesn't require a power outlet).

"€1500 including installation is too much for me; I had already obtained a cost estimate before."

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- "Fan" for the intake air, which, when loaded with a 300W alternator, ... The intake air is warmed by a few degrees, and as a side benefit... Base load of the engine increased. - Inject oxygen from the Torinister welding machine into the intake air. It could also be very helpful for the cold start process. - enrich the air intake with a large amount of oxygen before cold starting. Seal the intake manifold using a device connected to an oxygen tank. Propane burner and heat exchanger. Then the start sequence will also begin. Minus 60 degrees Celsius in Novosibirsk? No problem.

MacGyver and Dr. Snuggles send their regards... if you have any installation instructions for it, please share them!

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- and of course: high-quality motor oil with a high... Use a viscosity range suitable for the vehicle, such as 0W or 5W oil. fully synthetic

I agree with that, although it's probably also a matter of personal belief.
whether to use Longlife II (0W-30), Longlife III (5W-30), or something else.
"Using fully synthetic 0W-40 oil and changing it every 15,000 km."

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Okay, I think the package of measures is comprehensive enough.

Thanks, even though I don't think everything was meant to be taken *that* seriously...


Best regards,
gromit

One argument against deactivating the EGR system is that it takes significantly longer for the engine to reach operating temperature when the EGR is disabled.

What is the logical explanation for this claim, particularly in accordance with the first law of thermodynamics and the Carnot process?

In order for a motor to heat up its block faster at a given power output, it must have a lower thermal efficiency, meaning it must dissipate more waste heat.

While the overall efficiency decreases with EGR, this is less due to a poorer thermal efficiency and more due to a lower combustion efficiency, meaning more soot and hydrocarbons. Therefore, the engine with EGR does not produce more waste heat!

While a portion of the hot exhaust gases (which, at best, are only lukewarm when mixed with the cold intake air) flows over the engine's intake passages, briefly utilizing a tiny amount of exhaust energy to warm them, it is questionable whether this actually mitigates the actual cold start wear of the engine.

Because cold start wear (apart from incomplete combustion) is related to the lubrication system, with oil that is still too viscous, with the engine not yet fully lubricated, and with changes in the lubricating clearance geometry due to thermal contraction caused by different coefficients of expansion of various materials.

And is a lukewarm exhaust vent in the intake manifold supposed to seriously provide a solution?

EDIT: By the way, the lubrication system warms up partly independently of the waste heat from combustion, due to friction at the lubrication points and due to circulation. Therefore, a quick warm-up with moderate speed and load is more efficient in this case.
Therefore, for the EGR system, only the pre-heating of the intake passages to improve combustion would remain a possibility. However, this is rendered absurd by the fundamental problem of the EGR system, which inherently worsens combustion.

Point 1: There was already a thread about the heating topic before.
We can disregard Carnot & Co. here; the issue isn't the amount of waste heat produced, but rather the overall temperature level, which is significantly increased by the EGR system. Especially at low loads, the engine would otherwise cool down due to the intake of cold air, but this only appears to be the case with an uncalibrated display. The efficiency alone doesn't tell the whole story because it doesn't differentiate between exhaust and coolant losses.
The increased wear during cold starts in diesel engines is mainly caused by the thermal expansion of engine components, which do not have the exact same shape when cold as they do at operating temperature.

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Point 1: There was already a thread about the topic of heating.

Hi Christian,
Do you perhaps still have the link to that thread? (I've already searched for it).

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Especially at low loads, the engine would otherwise cool down due to... "It sucks in cold air, but this is only noticeable in one case." uncensored advertisement.

Several people have reported that an engine without an EGR system takes significantly longer to reach operating temperature.
to reach.
"By the way, I have a Volkswagen Golf 4 (with the ASZ engine). Does that mean my temperature gauge is an 'uncut' version?"

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Increased wear during cold starts has been a problem with diesel engines. The main cause is the thermal expansion of the... Engine components that, when cold, do not have exactly the same shape. have the same temperature as when they are in operation.

Since it's best to warm up the engine for wear-related reasons, there might be...
a non-electric auxiliary heater or a "minimal" parking heater that only...
which warms up the engine (not the interior) and which is slightly easier to install than a [something].
conventional parking heater?

Best regards,
gromit

gromit wrote:

by the way: I have a Volkswagen Golf 4 (ASZ), do I have an "uncut" temperature gauge?

Any advertisement that shows a device remaining at a perfect 90-degree angle is a lie. It should actually be "constantly" fluctuating.

Without knowing your specific vehicle, I highly doubt you have an un-dampened version. Only some of the early G3 models had a "non-dampened" version; I've only seen it in the VR6 (and only there). Later, around 1994-1995, a dampened version was installed (in the VR6), and my friend has an older TD (also a G3) that already had the dampened version. So, from '96 onwards, every Golf 3 definitely has a dampened display.

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Jede Anzeige wo auf 90° verharrt, ist ein Lügeisen. DHe has to. actually, they "constantly" fluctuate. Without knowing your vehicle, I highly doubt that you... You have the un阉ed version. Only some of the early G3 models had this feature. an "unmuffled" version, I have one in my VR6 (and also...). "I only know that from there." Later, I believe it was in the years 1994-1995, a... "A muffled version was installed (in the VR6 engine), my friend has one." older TD (also G3), which already has the muted sound. I had a version of that. So, definitely since '96, it has been... Every Volkswagen Golf 3 has a muffled advertisement.

I can confirm that, based on my experience with my G3 from '97, and of course, also with my...
The temperature gauge on the current G4 model remains stuck at 90° and doesn't change.
(once the engine has reached its operating temperature).

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Especially at low load, the engine would otherwise cool down. the "It sucks in cold air, but this is only noticeable in one case." uncensored advertisement.

But let's get something straight:
"Dimmed display" simply means that the display is slow to respond, i.e.,...
"Short-term changes are not visible; only the average value is displayed."
If you drive for a while with low load during the winter, why do you observe cooling?
Not with some delay?
Or is the temperature control system so good that it can compensate for different loads effectively?

Can the actual cooling water temperature be displayed via the air conditioning system?
A better metric would be the oil temperature, but to measure that, you need a sensor, as far as I know.
retrofit.

Best regards,
Gromit.

Hello!

gromit wrote:

But let's get something straight: "Dimmed display" simply means that the display is slow to respond, i.e.,... "Short-term changes are not visible; only the average value is displayed." If you drive for a while with low load during the winter, why do you observe cooling? not with some delay?

The display does not have a logarithmic response; instead, it operates with a step function.

Within the range of 72° to 112°, the needle points to 90°.
Within the range of 50° to 72°, the needle traverses the area from 50° to 90°.
Above 112°, the needle jumps directly to 112°.

During winter driving in low outdoor temperatures, the waste heat from the engine is often not sufficient to warm the coolant to 70°C. Therefore, the temperature gauge needle then drops back below the 90° mark.


Regarding the AGR (Abgasrückführung) system, it is important to refer once again to the exhaust emission regulations.
No engine manufacturer would voluntarily do things like that.
If manufacturers were allowed to build their engines according to their own discretion, TDI engines would still be rough and noisy, but they would consume approximately 15% less fuel and wouldn't have the same problem with low-speed acceleration.


BYE
TDI mechanics.

gromit wrote:

But let's get something straight: "Dimmed display" simply means that the display is slow to respond, i.e.,... "Short-term changes are not visible; only the average value is displayed." If you drive for a while with low load during the winter, why do you observe cooling? Not with some delay? Or is the temperature control system so good that it can compensate for different loads effectively?

Well, whether you call it "calibrated," "dampened," or something else, it essentially means that the display has a "plateau characteristic" (I can't describe it any better). For example, it will consistently show 90° from 75° to 100°. Therefore, temperature fluctuations caused by overheating or cooling won't be registered.

The control isn't good enough to keep the temperature at exactly 90°. Take a look at my engine. The fan turns on (first stage) at 90° and off at approximately 80°. The thermostat opens at 87°. This means that if it were actually staying at 90°, the fan would never turn off. However, what's very good (especially compared to a gasoline engine, my VR6 has about 15° difference) is that this range is already quite small. It probably has to do with the fact that the TDI produces less waste heat compared to a gasoline engine.

Here's an explanation: The engine warms up to 87°, and then it struggles to go much lower because a running engine always produces waste heat, and in a small circuit, it can only dissipate that heat to a limited extent. Since the engine is already warm, the interior of the car also becomes warm. The fan switch is located in the radiator, which means it doesn't activate until the engine has cooled down enough for the thermostat to close. Then, all it needs to do is cool the engine through the radiator, which allows those last 7° to be reached quickly.

Sometimes the first fan speed isn't enough, and you have to turn on the second one. At that point, the motor would already be at 97°C.

I'd say that, aside from extreme temperatures (and defects), the coolant temperature stays within a range of approximately 80 to 100 degrees. The fluctuations (87-80 and 100-97) are due to the system's delay. It takes time for the temperature to warm up and cool down.

The gauge has been showing 90° the whole time. Even before the thermostat opens (less than 87°, about 75° in mine) it goes up to the second level and slightly above. The values mentioned above correspond to the readings from VAG-COM (not just pulled out of thin air ), all related to my AKN engine.

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

"@tdi-schrauber"
You were faster and provided more accurate information .

tdi-schrauber wrote:

1) Within the range of 72° to 112°, the needle points to 90°. 2) Above 112°, the needle jumps directly to 112°. "3) During winter driving in low outside temperatures, the waste heat from the engine is often not sufficient to warm the coolant to 70°C. Therefore, the temperature gauge needle then drops back below the 90° mark."

1) 72 is close to my measured value of 75. I've never seen a reading of 112 before, so I estimate it to be closer to 100.
"Then you have a real problem. If the second stage and the viscous fan can't control the temperature, there must be a defect... Based on my measured temperatures and my engine."
3) In my specific case, I'm not entirely sure about that. Where mine decreased, the thermostat was broken. Even with extremely low temperatures and over 10 km of almost exclusively coasting (no acceleration), mine didn't get colder than 80°C, despite the heater being on (not at full load, as the interior was already warm). The engine can only dissipate its waste heat to a limited extent through the internal heat exchanger. In my vehicle, the heat generated by the engine during coasting is higher than the heat exchanger's capacity to absorb it. Perhaps it wouldn't happen at -20°C with full heating, but that's rare. However, to initially warm up the engine, you need to use the accelerator pedal, which obviously isn't possible during coasting.

EDIT:
I do believe that the operating temperature tends to decrease with newer and smaller engines. A small 3- or 4-cylinder engine with higher efficiency and the same heat exchanger for the interior could naturally experience more significant issues in this regard.

'Take a look at the coolant temperature reading using VCDS. On newer VW TDI engines, it fluctuates by approximately ±1°C – at least, that's what I see on mine – which indicates pretty good control.'

Devilseye503 wrote:

"Take a look at the coolant temperature reading in VCDS." 2) It fluctuates by approximately ±1°C in new VW TDI engines - at least in my case - which indicates quite good control accuracy.

Herr Antje wrote:

1) The values mentioned above, by the way, correspond to the values from VAG-COM (not pulled out of thin air ), and all are related to my AKN. "The control is definitely not good enough to keep the temperature at 90°. Take a look at my engine. The fan turns on (first stage) at 90°, and off (approximately) at 80°. The thermostat opens at 87°. This means that if it were actually staying at 90°, the fan would never turn off."

Okay, I admit it, I don't have a new VAG engine. However, some of the newer ones still drop to lower temperatures in winter (as reported here). Therefore, a 1-degree difference is already quite small. Additionally, we could check the temperature settings for the radiator fan; they should turn on at 91°C and off again at 89°C.

I could maybe create a log if I have time .

I haven't observed how the temperature behaves during the coldest part of winter yet, but in my normal driving cycle – meaning sometimes coasting and sometimes accelerating with full throttle – the temperature fluctuates around 90°C plus or minus 1°C.

I once had an old Passat diesel, and I was very surprised by how much the engine temperature fluctuated – a variation of plus or minus 10°C was the minimum.

Hello Robertf,

I've also been wondering about the ARL 1.9PD 110kW, as you asked.
It's lost somewhere in between the lines.

My thought was that mechanical wear could affect the positiveness of the dead zone.
AGR + higher combustion chamber temperature need to be considered together. Back then, as a novice with my cooled EGR system, I assumed that when the valve was closed, the coolant would still exchange heat, but only in the very last section of the exhaust manifold leading to the AGR. My reasoning was that if the AGR is functioning correctly, there's airflow in that area, meaning the dead end is sometimes open, and the heat transfer to the coolant is more efficient because there's a constant supply of hot exhaust gases.

Conversely, if it were closed, the higher combustion chamber temperatures would be a concern.
'These [additives] help to bring the engine block, cylinder head, and thus the oil, up to operating temperature more quickly. However, I have not achieved any scientifically proven results that have been measured and thoroughly verified.'
arrived.

Only one!!!! If it was -20°C, my engine wouldn't run smoothly. The first two minutes with AGR active were horrible!! A choking and sputtering sound, a wave of RPM fluctuations, an inconsistent gas pedal response. So forget about it, and thank the seller and the people here for this 'insider knowledge' that your engine has such an asthmatic condition, and that it's harmful*period*.

Take a look at this and the extensively illustrated package insert should definitely deter you from taking an antioxant, such as an AGR.

While some people say you should drink your morning urine, that's something you just don't get used to in Siberia.


Have a nice weekend!