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Not everyone can hear this, especially with radio blasting. Maybe bad batch of EGR valves ended up on CT assembly line at some point. This is why I got used one, as no one seems to be complaining on EGR valves in 2017 - 2019 MY. Even 2.0L CT has the same ERG valve.
 

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Not everyone can hear this, especially with radio blasting. Maybe bad batch of EGR valves ended up on CT assembly line at some point. This is why I got used one, as no one seems to be complaining on EGR valves in 2017 - 2019 MY. Even 2.0L CT has the same ERG valve.
The EGR you bought, does it have the same part number I listed in this thread?
 

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The EGR you bought, does it have the same part number I listed in this thread?
Yes, PN: 14710AA830 is widely used in Subarus for years, and appears to be made by Mitsubishi.

Mine looks like the one you posted in the picture, so it the used one from Impreza 2017 with 15K miles.

I found good thread about it: EGR Valve, how to test it? & what causes the carbon

Possibly weak spring, deposits or manufacturing defect may cause the valve not to be fully closed and there is no way for ECU to figure this out when leak is small, really stuck valve will be flagged by EGR test, but it is done by ECU at 5 C degrees ambient temperature.
 

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Unlike the dealer, I could inspect the "bad" EGR valve, disassemble it and possibly find why it was not operating correctly.
 

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I need the procedure, torque specs for EGR valve replacement and this is available on Subaru tech info website with subscription. EU site is up, but US is offline for some reason. This 2.5L is very new for 2021, so not very many alternative sources are available for this info.
 

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I need the procedure, torque for replacement and this is available on Subaru tech info website with subscription. UE site is up, but US is offline for some reason.
Probably down for general maintenance.
 

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Not sure why they needed:
14035AA690 - Gasket intake manifold - Quantity: 4
The EGR valve removal/installation does not require Intake Manifold removal. Only Intake Boot, Throttle Body and Purge Control Solenoid Valve are removed.

Anyway, I am in the process of testing a solution that does not involve EGR valve replacement or SP rated oil or even talking to the dealer. If successful, I will post the info soon. I think what we are observing is a result of known issue in gasoline engines, babying engine and class of gas used, CT 2.5L engine is just very sensitive. Anybody should be able to fix it by doing simple operations while driving and changing a few habits to keep it healthy.
 

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Not sure why they needed:
14035AA690 - Gasket intake manifold - Quantity: 4
The EGR valve removal/installation does not require Intake Manifold removal. Only Intake Boot, Throttle Body and Purge Control Solenoid Valve are removed.

Anyway, I am in the process of testing a solution that does not involve EGR valve replacement or SP rated oil or even talking to the dealer. If successful, I will post the info soon. I think what we are observing is a result of known issue in gasoline engines, babying engine and class of gas used, CT 2.5L engine is just very sensitive. Anybody should be able to fix it by doing simple operations while driving and changing a few habits to keep it healthy.
What are you even saying? You NEED to remove the intake in order to remove the EGR pipe because it’s connected to the intake. You want new gaskets so you don’t have any leaks...

If you’re referring to “top-tier” fuel, other members have tried with no fix. It may reduce the problem but it will ping once the oil temp is achieved in order to duplicate the sound.
 

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Not the intake manifold, according to service manual for Crosstrek 2021 2.5L. Please, do not argue - I am not a dealer after all. “top-tier” fuel is part of the upkeep, but it would never fix the mess created in the first place.
 

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Not the intake manifold, according to service manual for Crosstrek 2021 2.5L. Please, do not argue - I am not a dealer after all. “top-tier” fuel is part of the upkeep, but it would never fix the mess created in the first place.
I have the 2.0L engine. The 2.0 & 2.5 are literally the same engine, only difference is one engine has a bigger displacement, that’s it. I think you have to remove the intake because you’re replacing the entire system, not just the valve. But do what you want.
 

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2.0L is even simpler as it does not need purge valve removal (not present or located somewhere else). In any case, I do engine rebuilds and repairs by myself, so even whatever is written in service manual I will avoid/skip half of the steps they prescribed as it is written by people who never disassembled or assembled anything. A two pipes that are part of the EGR have no effect on EGR valve operation and only top one connected to intake manifold is removed to help with removal of the EGR valve. Who knows, may be dealer did not read it and just went with it on their own to get EGR valve removed, making a few extra disassemblies. Yes, a few metal gaskets on the top are needed as those are compression type and could not be reused, although those are very cheap - $2.50 a piece.
 

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Today I was able to verify the knock is gone on 87 octane at oil temperature well above 196F. I filled it with 93 octane by mistake to start the cleaning/burning cycle, so I have to drive a while until the tank became empty to reach my final conclusion. Also, I hooked up my OBDLink App and MX+ adapter and created custom dashboard screen to monitor EGR Valve operation alone with other important metrics. What a surprise to learn the fact - it is completely closed with pedal to the floor or off the pedal situations. And when would it be open at its max value (70.2%)? Any guess? It is when we are operating vehicle in exact way the engine starts to knock. What a surprise, indeed. Also, ECU knows where EGR Valve is by calculating MAF sensor input. So when it wants to open or close it - valve is mechanical and it has a small delay, so it would post errors while EGR valve adjusts to specific value set by ECU - it only takes fraction of a second to adjust.

So basically, Subaru engineers tuned EGR valve operation for very clean engine that has no carbon deposit buildup. When small amount of carbon is accumulated - those hot exhaust gases + hot carbon specs will cause LSPI that eventually leads to engine knocking.

The easiest solution would be for Subaru to make EGR valve opening less aggressive, so it allows the engine to operate with moderate carbon deposit amount, ergo as most of the car engines are tuned.

Or we can just maintain our engines pretty clean by using Top Tier Gas or using Fuel/Upper Cylinder cleaners regularly. I used this one: "BG 44K Fuel System Cleaner Funnel" https://www.amazon.com/BG44K-BG-44k...em+Cleaner&qid=1614193631&s=automotive&sr=1-2

What to do if you already in this knocking dudu? Just add reputable Fuel/Upper Cylinder cleaner and fill tank with Top Tier Gas. Then you will need to rip it with accelerator to the floor to max allowed speed. may be a bit more depending on situation and your knowledge of the road and police habits. It needs to be done with load - means you need to go moderate uphill to load your engine to the max, so it will burn the carbon inside your engine when operating in this conditions naturally. And in general drive your car while tank is empty in spirited way to get rid of deposits as much as possible.

The easiest way to get oil temperature up is to drive with engine around 5000 RPM in manual mode - it usually takes less than 30 secs to boost oil temp to > 200F. So you can verify if knock is gone at temp above 196 F.

Here is screenshot of the EGR Valve at max open position:
 

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Today I was able to verify the knock is gone on 87 octane at oil temperature well above 196F. I filled it with 93 octane by mistake to start the cleaning/burning cycle, so I have to drive a while until the tank became empty to reach my final conclusion. Also, I hooked up my OBDLink App and MX+ adapter and created custom dashboard screen to monitor EGR Valve operation alone with other important metrics. What a surprise to learn the fact - it is completely closed with pedal to the floor or off the pedal situations. And when would it be open at its max value (70.2%)? Any guess? It is when we operating vehicle in exact way the engine starts to knock. What a surprise, indeed.

So basically, Subaru engineers tuned EGR valve operation for very clean engine that has no carbon deposit buildup. When small amount of carbon is accumulated - those hot exhaust gases + hot carbon specs will cause LSPI that eventually leads to engine knocking.

The easiest solution would be for Subaru to make EGR valve opening less aggressive, so it allows the engine to operate with moderate carbon deposit amount, ergo as most of the car engines are tuned.

Or we can just maintain our engines pretty clean by using Top Tier Gas or using Fuel/Upper Cylinder cleaners regularly.

What to do if you already in this knocking dudu? Just add reputable Fuel/Upper Cylinder cleaner and fill tank with Top Tier Gas. Then you will need to rip it with accelerator to the floor to max allowed speed. may be a bit more depending on situation and your knowledge of the road and police habits. It needs to be done with load - means you need to go moderate uphill to load your engine to the max, so it will burn the carbon inside your engine when operating in this conditions naturally. And in general drive your car while tank is empty in spirited way to get rid of deposits as much as possible.

The easiest way to get oil temperature up is to drive with engine around 5000 RPM in manual mode - it usually takes less than 30 secs to boost oil temp to > 200F. So you can verify if knock is gone at temp above 196 F.

Here is screenshot of the EGR Valve at max open position:
You do know that the Crosstrek is direct injection? Therefore, any fuel additives you put in your tank will NOT reach the intake valves. You'll either have to pull the intake off and blast it with walnuts or run the Subaru Upper Engine Cleaner/Carbon Cleaner solution.
 

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You do know that the Crosstrek is direct injection? Therefore, any fuel additives you put in your tank will NOT reach the intake valves. You'll either have to pull the intake off and blast it with walnuts or run the Subaru Upper Engine Cleaner/Carbon Cleaner solution.
Yes I know and I did not care about intake valves at all. It is what is inside the cylinder that matters. Did I mention intake valves? or any valves?
 

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Yes I know and I did not care about intake valves at all. It is what is inside the cylinder that matters.
How can you have carbon build-up? Your car only has 6,000 miles! Unless your driving habits are 99% city and 1% highway...
 

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How can you have carbon build-up? Your car only has 6,000 miles! Unless your driving habits are 99% city and 1% highway...
Because of I know what I did with my car and why and when knocking started. It started at ~3000 miles after I switched from Exxon Mobil to the cheapest gas I could find Lukoil/Speedway and etc. and my car has > 13K already. It is not like a crust covering the inside - it is black powder like substance you can easily wipe with your finger, the only problem you can not get there when assembled.

And by examining the used EGR Valve from Impreza with 15K. Unless you use Top Tier Gas - it will keep building up little by little. Unless you burn it by driving it like you stole it or with engine load (do not even need any cleaner) or use cleaner or ...
 
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