Intake Valve & EGR: Function & Repair

Hi,

I temporarily disabled the AGR (selective catalytic reduction) system in my Mazda6. Now I've noticed that there's still an intake control valve located in the intake path, between the intercooler and the engine.
Depending on the condition of the engine, it may be partially or completely closed.
I suspect this valve is located in the intake path to create a certain vacuum, so that when the EGR valve is open, exhaust gases are drawn into the engine?

If things are as I suspect, wouldn't it also be logical to close off this valve in the intake path?
Is there any potential for further optimization here, or am I completely wrong?

Here's the schematic structure:


Part number 33 shows the location of the inlet valve.

Here it is again, but bigger: http://www.freepatentsonline.com/6962140-0-large.jpg

To understand this better, you need to know more about the engine. Models with ASZ (EURO3) engines have a valve in the intake area behind the EGR system. This is a shut-off valve to allow the engine to "comfortably" shut down. EURO4 engines must influence the EGR rate more strongly, so a valve is placed before the EGR system to reduce the amount of fresh air entering. If your engine is like the one in the picture and the valve control is still working, blocking the EGR system could cause problems.

First of all, thank you for your reply.

I properly sealed the AGR. Otherwise, the AGR valve is functioning as usual.
The engine seems to be responding very well to it. It definitely feels better to drive, especially in the partial load range.

The inlet control valve can be adjusted in two stages: partially closed and fully closed.

There is another valve located in the intake path. It is labeled as number 38 on the diagram. It's called a "swirl generator" (or something similar).
From the perspective of the air filter, it is located BEHIND the EGR valve.
The intake shut-off valve is located there. It appears to be blocking the intake path, so that the engine is drawing in exhaust gases instead of air.

The diagram above is exactly from my engine, so you can use it as a precise reference.

Could it be that the swirl flap (3 is intended to prevent what is known as "after-diesel"? What other function could the intake closing valve (33) have? Should I disconnect it to see what happens?

Good morning, everyone.

What does the 27 mean? To me, it looks like the aforementioned "whirligig...flap" is located in a bypass to the actual intake manifold, perhaps a type of regulated swirl channel. However, it would be unsuitable for shutting off the engine, due to the bypass. Your other flap before the EGR? Is this flap open in its resting position? If so, I would simply try it, but! Of course, it's possible that your MSG (Motor Steuergerät - Engine Control Unit) will store an error because the amount of fresh air being drawn in increases in different operating conditions, and in order to meet the Euro standard, the MSG would naturally try to compensate, which would then fail without a functioning flap.

Best regards,
sebastian

Yes, I didn't see that about the bypass.
I'll try that out later and let you know how it goes.

I'm having the same problem.
It's questionable whether simply blocking it off will actually work and whether the control valve will remain open or stay open.
Alternatively, I think it might be possible to remove the flap wings as well, if that proves to be less problematic.

Okay!
I'm just wondering if this valve is part of the EGR system or if it actually performs other functions.
I checked it out earlier and went for a drive. I didn't notice any difference. The 0-100 km/h acceleration is still 10.3 seconds.
However, this valve is probably not functional under full load conditions anyway.
The warning light did not come on. According to the documentation, it only illuminates when the control valve signal voltage is implausible during two consecutive trips.

Hmmm .
How did you do it? Did you simply disconnect the vacuum hoses from the canister, or did you remove the connectors from the control valves? The latter might cause an error on the second run.
but just on the side, I don't really think that the modification with the valve will achieve anything, because even if more air gets through, there's already an excess of air in the cylinders, and the amount of fuel would first have to be adjusted or increased?!!

best regards
sebastian

Okay, so I simply deactivated the two solenoid valves by disconnecting their power supply. After the test, of course, I plugged the connectors back in. I didn't have the option to clear the error memory.
You are right, the excess air is more than sufficient, especially in the partial load range. I am only hoping for a small optimization in the partial load range, through less restricted intake paths.
Something like: Even small things can cause problems.

It is also possible that the valve closes completely when the engine is turned off, but only closes halfway in the partial load range. The valves and the diaphragm are designed to handle these two states.
Otherwise, it could simply be controlled using a duty cycle.

Hello, when I was working on the SDI, I removed the air filter so I could see the valve directly.
It's open when the engine is off, and it should also stay mechanically open due to a spring mechanism. When I start the engine, it remains open. When I give it gas while the engine is idling, it also stays open. When I turn off the engine, it closes briefly, then opens halfway, then fully opens, and remains open. So, the shut-off valve function is working.
The question is:
Does it possibly close halfway when the engine is warm and while driving (as part of the AGR system)?
The electrical control (4-pin connector) can be disconnected and it remains open, but this results in an error entry in the MSTG. Is there a way to avoid this error, even when the control is disconnected? }

Okay, you're right again. However, I assume that if you were driving without the valve control, you also turned off the engine (without stalling it, of course). Therefore, according to my understanding, the exhaust valve control function would be disabled, and the valve is actually just a component of the EGR control system. My suggestion would be to simply disconnect the vacuum hoses and, instead of sealing them, equip them with small filters from the motorcycle fuel system to prevent contamination of the vacuum system!
This method prevents at least one type of error because the voltage signals from the valves remain plausible, and there is no further query about the position of the valve, for example.

ps. Regarding your question from above, I personally often only experience the "afterglow" with gasoline engines .
This is caused by deposits in the combustion chamber, where the accumulated fuel residues spontaneously combust in a kind of glow process within the engine!

Best regards,
sebastian

Unfortunately, I can't see my intake shut-off valve. It's located quite a ways behind the intercooler.
I will take another look at it tomorrow.
I didn't notice any "afterglow" during my testing. Therefore, I'll focus on the valve that only partially closes the flap. This would leave the "afterglow function" unaffected.
It would be worthwhile to investigate how the engine behaves under partial load conditions with the valve deactivated. Are there any standard tests for this?
At first glance, I didn't notice anything.

And one more thing: What exactly does the second flap do? This swirling thing?

"The 'whirligig' reminds me of the swirl intake manifold or throttle intake manifold in a gasoline engine, where a special air intake system optimizes the fuel filling level and atomization for more complete combustion. *whoosh* "
I would leave the bypass valve function enabled on the turbocharger. My Audi A6 C4 2.5 TDI doesn't have this function, and if the turbo leaks oil without it, it acts like a jet turbine and can tear your engine apart. This way, you can still cut off the airflow with the ignition off, and you won't end up looking like a V2 rocket.

Okay... the turbocharger won't be used for an aircraft turbine. Instead, it forces oil through, which the piston engine then uses as fuel for self-ignition. Since you can't control this process with a key and accelerator anymore, you shouldn't have a shut-off valve. Instead, it's recommended to downshift the engine to a high gear. Nothing will break in the process; beyond 6000 RPM, the pistons will start closing the valves because the valve springs can't keep up. At that point, it's essentially over because the engine won't have enough compression for self-ignition anymore.

Okay, the outcome remains the same: engine failure --> a shut-off valve makes sense.