AGR Valve Stuck? Reasons & Solutions

Hello,

I'm really curious why, in many posts, closing the AGR valve is already being done or recommended as the first step.

Sometimes, you get the feeling that you're starting at a disadvantage, even with a fully functional AGR system.

To my knowledge, the EGR system is designed to prevent nitrogen, an otherwise inert gas, from reacting with excess oxygen in excessively hot zones of the combustion process to form NOx.

(NOx refers here to all possible compounds of nitrogen N and oxygen O.)

Therefore, the EGR system only removes the excess air that is not necessary for the combustion of the injected amount of fuel.

Therefore, we can't even expect an increase in performance!

Best regards,
Hardy disc.

Hi.

You are right; it is prohibited and unnecessary to restrict "vehicles that are designed for optimal performance" to low speeds, especially when they are often driven at full throttle.
"However, especially in engines that are frequently used in areas with high EGR activity, are driven mostly on short trips, are older, or produce a lot of soot, the EGR system, intake manifold, etc., can become clogged. This restricts airflow to the engine, and the EGR system then produces even more soot."
"Disabling the EGR valve in newer engines is no longer possible without generating an error code, and it is often only used for troubleshooting when the EGR valve is constantly open or stuck, or when the valve itself is defective."
Due to the legal and environmental policy aspects (classification of exhaust emissions into a category), this measure cannot be permanently installed.
However, even the TÜV (German technical inspection agency) doesn't notice it.
Hopefully, I've contributed to the formation of opinions.

teileklaus wrote:

Due to the legal and environmental policy component (classification of exhaust emissions into a category), this measure cannot remain permanently

installed. }That's not entirely correct, Klausi. In fact, the car is no longer allowed to travel even a single meter on public roads. The registration (BE) expires immediately upon deactivation!

Yes, yes, I understand, but clever workshops also use this method of temporarily sealing something to rule out potential problems, right?
And I wouldn't criminalize that.

As you already mentioned, a portion of the exhaust gas will be mixed with fresh air.
(between the turbocharger and the intercooler).
The required amount of air is therefore regulated by a defined mechanism when the EGR valve is open.
Exhaust manifold replaced.
This reduces the amount of fresh air controlled by the mass airflow sensor.
This is a measurement used to calculate the injection quantity.
<edit>Further research: There are LMM signal compensation mechanisms in various control units.</edit>

Furthermore, the back pressure of the exhaust gases before the turbocharger is reduced.
This results in a slower rate of change or increase in the speed.
Turbos, often referred to as 'throttle response.'

Empirically proven to be successful.

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

'lg.'
'Best regards.'

hardyscheibe wrote:

Hello, I'm really curious why, in many posts, closing the AGR valve is already being done or recommended as the first step. Sometimes, you get the feeling that you're at a disadvantage from the start, even with a functional EGR system.

The owners of the engines, whose supposedly beneficial EGR systems show effects like those in the photos here,https://community.dieselschrauber.org/en/viewtopic.php?t=3095 are actually at a disadvantage from the beginning if they ever need to use the maximum paper-based power output of their engine...

Quote:

Not quite, Klausi. Actually, the car is no longer allowed to travel even a single meter on public roads. The operating permit (BE) expires immediately upon deactivation!

That shouldn't happen even with exhaust-related errors, but what can you do? Load it onto a truck and take it to the workshop's air-conditioned roller test bench so that a brainlessly defined law is satisfied?!

For many older vehicles, the average exhaust emissions reading, when measured with a closed ARF (Abgasrückführung - Exhaust Gas Recirculation), will appear better across all pollutant components.

Hello,

Thank you for the comprehensive answers. The misunderstanding has now been cleared up!

I've also seen carbon buildup in the intake manifold many times, but I believe it has become significantly less frequent with better (more modern) engine oils (currently using Agip Formula Future 5W30).

In my opinion, temporarily disabling the AGR (Abgasrückführung) for diagnostic purposes is completely harmless. After all, you are allowed (should) to drive to the workshop even with a burning MIL (Malfunction Indicator Lamp) immediately!

Anything that goes beyond that will become obsolete anyway with the introduction of the blue environmental sticker!

Hi hardyscheibe.

hardyscheibe wrote:

Temporarily disabling the EGR for diagnostic purposes is, in my opinion, completely harmless; after all, you are allowed (should) to drive to the workshop even with a burning MIL (immediately)!

Closing it will be attributed to you as intentional wrongdoing! Therefore, you are knowingly committing a crime. If the MIL comes on during the drive, you are not responsible for that and can clearly drive to the workshop in that state.

Hello everyone,
Just a quick note, and it's related to trips I've taken in/with various new cars.
Do the newer (larger) engines, which often have a 7-speed automatic transmission or a long-geared 6th gear, and which typically run at around 2,000 RPM at 150 km/h (approximately 93 mph) on the highway, essentially operate as long-distance vehicles, constantly experiencing noticeable engine braking (AGR) rates? Is there a graph available showing the partial load and AGR behavior for these engines?
haithamina

"If you have a lot of time, you can create a dataset without using the AGR (Abgasrückführung) system. You can use VCDS to log the amount of air the engine is drawing in under different load conditions, and then compare that air mass to the air mass readings obtained with the stock AGR system."

Then you can see which AGR (AdBlue) rate is being used in which operating modes. However, without any further options for adjustment, this information is likely to be of limited interest. Ultimately, the only thing that matters to the interested user is the right foot.
Generally, as the load increases, the AGR (Abgasrückführung) rate decreases. Therefore, if you want to minimize carbon buildup, you should always maintain a constant speed on the highway. In particular, truck drivers who drive just 2 km/h above the speed limit and block all lanes for kilometers to allow a truck to pass are operating in an extremely active AGR range, which over time can cause the car to malfunction if the driver ever wants it to.

Best regards, Rainer.

Is there really no way anymore to influence the AGR (Abgasrückführung - exhaust gas recirculation) on the newer models? The 'verstopfen' (clogging) issue has been addressed for a while, but 'runteradaptieren' (reducing adaptation) isn't working on our BMN engine either... (incorrect login...)

dieselschrauber wrote:

If you have a lot of time, you can create a dataset without AGR (Abgasrückführung) by logging the amount of air the engine draws in at different load conditions using VCDS, and then comparing that air mass to the air mass with the standard AGR system.

Hi Rainer,
Okay, I understand. My concern is that I'm familiar with how the 1.9 TDI engine behaves in this regard. Especially when driving on the highway at speeds above 140 km/h, the exhaust gas temperature (EGT) rises so high that the EGR system becomes irrelevant.
If I look at other, modern engines with corresponding transmissions, they operate at around 2,000 RPM at the average speed on German highways, and therefore have correspondingly high AGR (Abgasrückführung) rates when "cruising." They should also be able to provide sufficient power, as seen in the V (vehicle) + 2 km/h driving profile.
haithamina

Hello,

I wanted to disable the AGR valve in an Opel Zafira to make sure that this valve, which occasionally gets stuck, is really responsible for the cold start problems (in addition to the occasional loss of power), since the valve costs €648!

Due to its modern, water-cooled design, this valve is an integral part of the intake manifold/AGR system and cannot be sealed with gaskets or plates.

Similarly, both mechanical locking and blocking, as well as unplugging the device, will immediately trigger emergency mode.

The two remaining options would be to separate the valve from the actuator (using a flexible connection).
or to connect a second, working valve (haha) to the wiring harness during the test.

Fortunately, the valve is already available online for €220, and I explained to the customer that no one wants to start their day by having to deal with their own problems, so the issue is resolved.

The conclusion from all of this is: the newer the cars, the more deeply integrated the electronics are! Experimenting is no longer an option!

On the other hand, history also shows that the legislator has achieved its goal: a vehicle that exceeds its emission limits at the time of registration or otherwise does not meet the requirements will be detected and taken out of service at the latest during the next vehicle inspection (HU) or emissions test (AU).

best regards, hardy disc

Quote:

They should also work quite well,

Not necessarily.
And the Golf reached its first 122,000 km (approximately 76,000 miles) at that very steady pace -> the EGR system was only vaguely related to Russian technology. And that was after another 8,000 km (approximately 5,000 miles) of city driving.

Quote:

Due to its modern, water-cooled design, this valve is an integral part of the intake manifold/AGR system and cannot be sealed with gaskets or plates.

One has nothing to do with the other.
In VW vehicles, the cooled EGR valves are also lockable, but the engine control unit (ECU) detects the locking.

m;

dieselmartin wrote:

One thing has nothing to do with the other. At VW, the cooled EGR valves can also be locked - however, the engine control unit (ECU) detects the lock.

You're right, Martin, I know what he means. I recently had a 2.2 DTI with EGR problems. The problem there is that there is no separate pipe for the EGR; the exhaust gases go through the cylinder head to the valve.