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Discussion Starter · #1 ·
Hello,

I have a Subaru Forester MY13, 2.0 diesel (EE20) with a mileage just at 175000 km. It's always been served at an authorized Subaru workshop, but the day after the last service some weeks ago, the DPF light came on for the first time since I bought the car two years ago.

So I started reading up a bit on the DPF and plugged in an ELM327 OBD2 adapter and started to log the trips. I always drive >20 km and during the trips, the DPF regen gets activated pretty much each trip, as soot value reaches 69 %. Soot then further increases to about 85-95 % before it decreases, and at 19 % (typically 12 minutes), DPF regen deactivates.

The oil dilution counter kept increasing until it reached 10 % and then the DPF light started blinking. I spoke with the workshop and they scheduled a time a couple of days later, and during this time the oil dilution increased to 12 %. The dealer changed oil and filter and zeroed the counter. That was all they did, no further troubleshooting, and they told me they must have forgotten to zero the counter on the last service (so I didn't have to pay).

OK, so now the DPF light didn't flash anymore, but it still came on and went off during each trip just as before, and the oil dilution counter kept increasing. One day upon acceleration when I had the trailer hooked on, the DPF started to blink, check engine light came on, cruise control indicator started to blink and an alarm text told me something was wrong with the exhaust cleaning system.

Since I read out an ash ratio of 67 %, I decided to remove the DPF and send it away for cleaning. It came back with a test protocol that seemed very promising. Pressure went down from 93 mbar to 24 after cleaning, and flow went up from 103 m3/h to 515.

Now the DPF is reinstalled and fault code reset (P2463: Diesel Particulate Filter Restriction - Soot Accumulation); soot, ash and oil dilution are zeroed; this was done by the authorized workshop. But on the first trip, DPF light came on and went off twice. I have not yet connected the OBD2, but my gut feeling tells me something else is wrong. I also experience low power when accelerating. It just feels a bit weak. Idle is good though.

Yesterday, I began dismounting the EGR valve to see if it's clogged. I've came so far that it's free, but it can't get pass the EGR cooler... I have searched the forums and studied the diagrams of the euro4 version, but apparently it differs from the euro5 that I have. Any tips on how to proceed?

However, I found another thing. The air duct hose that connects the intercooler to the throttle body is cracked. Could this explain the sooting up!?

Do you any other ideas on what could be clogging the DPF? I'd rather not clog it again, now that it's clean... Should I remove the intake manifold to see it that is clogged with soot?

Here's some pictures!

Log data on a trip before oil dilution counter was reset:
dpfsub1.png
Log data on a trip after oil dilution counter was reset:
dpfsub2.png
Cracked hose - EGR valve - Throttle body - EGR cooler blocking the passage
IMG_0329.JPEG IMG_0314.jpeg IMG_0323.JPEG IMG_0308.jpeg
Thank you for listening!
 

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2012 Forester 2.0D 6MT
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The answer is yes, the split intercooler pipe was causing excessive soot production and clogging your DPF. It's extremely common on these engines, I'd say it's the number one cause of DPF issues. At least now you have a clean and free-flowing DPF since you had it cleaned.

Also I would recommend cleaning out your intake manifold. It's unlikely to have contributed to the DPF issues, but they do get extremely full of soot at this mileage, which can eventually lead to a cylinder being starved of air. This will cause a very high EGT in that cylinder and potential piston failure. I think this is true of most modern CR diesels. The combination of soot from the EGR and oil vapour from the crank breather are the source of the sludge that you will find in your intake. You can eliminate the oil vapour by fitting a catch can (Mann-Hummel Pro Vent is a popular one).

I personally have only blocked off my EGR with a blanking plate, and I recommend it. I rarely get the error code (mine is also Euro 5). But it improved my economy and increased the DPF regen intervals significantly.

You can see some photos and get some pointers from my intake cleaning here:
('09-'13) - 2011 - Intake manifold removal for...
 

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Discussion Starter · #3 ·
Sound very promising, thank you!

poop! That was way pooptier than I thought physically possible. :-D
I will take you advice and clean mine. I'll read through the thread you linked to.

I just managed to pull out the EGR valve. I found a 12mm bolt just above the lower hose on the EGR colder. With that loosen a bit, I could jiggle the valve out. It doesn't look very bad, or what do you say?
IMG_0337.JPEG IMG_0338.JPEG
I took the lid off and rotated the plastic gear by hand, and the valve plate turned easily, and turned back to closed position by spring when I let go. I will of course clean it before putting it back.

Oh, another thing: What gaskets need to be replaced when taking down and remounting the inlet manifold?
 

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2012 SH Manual Diesel
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The air duct hose that connects the intercooler to the throttle body is cracked.
Could probably start a Class Action against Subaru, for those dodgy Intercooler hoses. 😂

Its such a common failure, and many have led to issues with DPF, EGR, or Intake manifold. Many of which, have been very expensive and frustrating for the owners; and/or have required multiple trips to workshop, or having the car off the road.
 

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Discussion Starter · #5 ·
OK, that's it for tonight - it's dark and the mosquitos are all over me.
Instead of trying to interpret what's up and down on the sketches from the service manual, I went for a more hands-on approach and got rid of everything that was obviously in the way, and then I took off the eight M12 bolts holding the intake manifold (four on each side). I thought that by doing so, I would find out what's still in the way when trying to remove it. However, the manifold is stuck, and instead of using violence I end it for today and continue tomorrow... Are there any risky caveats or can I keep on going?
 

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2010 Forester Diesel 6sp Manual
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Hi, you have a platic manifold, right?
It wont come out easily, there is still stuff in the way but it is possible to wiggle it out.
Have you separated the 2 parts from the intake manifold? The lower, metal one and top plastic one. Metal one is where throttle body and egr is mounted.
As for gaskets, they are not gaskets, but o-rings, i reused mines once with no issues, but bought new set for next cleaning.
 

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Discussion Starter · #7 ·
Hi!
Yes, it's plastic and here's what it looks like just now:
I have loosen the two parts, yes.
Do I need to pry it off or should it loosen easily?
 

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Discussion Starter · #8 ·
OK, baby's out!
I had to remove two brackets holding the manifold in place on each side.
I'm glad I took your advice and removed it - there's lots of soot here. Not quite as much as @notnothing but still, it looks like she's been smoking a pack of Gauloises unfiltered a day for a hundred years. Now the fun part begins. I intend to get it "spark joy"-clean.
Pictures to come.
 

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2012 Forester 2.0D 6MT
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Nice work. How does it look down inside the aluminium plenum? Mine was by far the worst in the bottom of that.

Here is a diagram for reference, from Partsouq (it would've been more helpful before now, sorry):

554134
 

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Discussion Starter · #11 ·
Thanks for the diagram!

The aluminium plenum was even dirtier. The sensor (temp? labelled A on the diagram above) in the throttle body house was so full of soot and oil that you couldn't even see it. And the channel between the EGR valve and the other end of the manifold had plenty of poop in it.

Now it's shining clean though (almost), but apparently so am not I. :)
I took everything apart and cleaned it with engine cleaner, sponges, brushes, rags, water and finished off with a citric degreaser I use on the bike (it smells good, like orange).

I guess I need a new gasket for the throttle body (16175 on the diagram). The 14035*B and #2 look good and I might just clean them and reuse. Or would that be stupid?

Now the biggest question mark is what to do with the soot in the intake canals in the engine?! Can I just leave it?

(Pictures will come later).
 

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I reused all of the gaskets and had no problems. As long as they're not torn/damaged, you should be fine.

I personally did nothing with the soot inside the heads. It was only a really thin layer, so I just let it be.
 

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Discussion Starter · #13 ·
Now it's clean and back together again. I reused the gaskets and only replaced the cracked hose. After assembly, annoyingly one bolt never found it's way home... it's an M8 (I think) with 12 mm head, the same size as the two on the intercooler.
Anyway, the car runs much better now! The engine is quieter, and before I had a hissing sound when accelerating, which must have been the air escaping through the crack.

Here's some pictures:

554181

A spoonful of this a day...!


554182

Can you spot the sensor...?

554183

Clean as cutlery?

554184
 

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Discussion Starter · #14 ·
I looked at the logs and I'm a bit confused.

Today, I drove two trips: a short of 18 km and a longer of 65 km.

On the first trip, soot level started at 48 % and increased to 69, then DPF regeneration got activated but without DPF light turning on. Soot decreased to 10 % and then DPF regeneration turned off.

On the other other trip, soot level increased rather quick to 45 percent, then at a slower rate to about 59 where it stayed for a while until it started to increase slowly to 69 %, when DPF regeneration turned on and soot level quickly fell. Still no DPF light.

Oil dilution increased from 1 to 2 %.

The car runs very well and there's no sign of the sluggishness I felt before.

Is this normal? Should I expect soot level to become more stable over time?

554185
 

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2010 Forester Diesel 6sp Manual
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Nice work. On mine also soot % is all over the place. Only time I see it increasing "in a normal manner" is on highway doing steady speed. As soon you start to decelerate and accelerate, soot can change +10% rather quick. On mine I have seen 50% on first 50km after regen, next morning starting the car it can quickly drop to like 30%. I had a chance to do faster driving (130kmh) not long ago and that's the speed where soot actually decreases, because of high exhaust temp. I think towing a trailer would do the same.
Soot is calculated by ECU from fuel amount burned, air mass, differential pressure and EGT. On slow stop and go traffic these parameters are all over the place and thats why soot % fluctuates also. Atleast thats what I think.
I made a tool to monitor what's happening with the DPF
('09-'13) - 2010 - DIY ► DPF Monitor!
 

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2012 Forester 2.0D 6MT
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Good job! Sounds like you've got it sorted. I agree with DieselForry, the soot figures rise and fall a lot, so your DPF stats seem normal. Regen is normally triggered at 65% soot accumulation, from memory, and does not activate the DPF light. The light should only come on if there's a problem, such as oil dilution exceeding 10% or if the soot/ash numbers get very high.
 

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Nice work, at 170k service the mechanic did that too - clean EGR, intake, replace 3 gaskets . DPF behaivour still the same : 500km+ on highway, 100-250km mixed driving . What is bothering me the most is that i drive 500km with no regeneration, and next day when i need to drive in town...boom , regen active and sometime i need to stop it. Next day..same.another regen..another miss..:( I am really thinking to delete from ECU the EGR ..but not really convinced about the consequences .
 

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Discussion Starter · #18 ·
Soot is calculated by ECU from fuel amount burned, air mass, differential pressure and EGT. On slow stop and go traffic these parameters are all over the place and thats why soot % fluctuates also. Atleast thats what I think.
Do you have any more details on this? Also, is it possible to retrieve burned fuel amount via OBD, either as a single parameter or if it's possible to calculate it based on injector flow and time open?

Your Arduino project looks nice! Mind sharing the sketch? I looked quickly into building an OBD logger based on an ESP32 and a wired ELM327 (RS232 over USB), but found a Python library and thought it would be easier to use a raspberry pi. I've just played a bit with the library but have successfully read out ash ratio (PID 221149). Until I've more free time to play around, I'm using an android tablet with the pro version av Torque, and then I export the csv file and analyze it with python (pandas).

Tomorrow I'll be going on a longer trip (200+ km) and I'm eager to see how it goes.
 

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Also, is it possible to retrieve burned fuel amount via OBD, either as a single parameter or if it's possible to calculate it based on injector flow and time open
There is a parameter "injection ammount" that is fuel injected in one stroke in mm³ i think. Then there was a PID for instant fuel consumption, I have it written somewhere.
As for air mass there is air mass pid which was grams per second, if I am not wrong, but there also are target air mass and actual air mass in mg per stroke.
Do you have any more details on this?
Not anything very specific or useful, I think.
Mind sharing the sketch?
I can, but looks like next week only, since I am on holidays.
OBD logger
Logger is nice, but I wanted something that shows data real time.

ESP32 and Pi are unknown territory for me since Arduino can do everything I need for now.
I've just played a bit with the library but have successfully read out ash ratio (PID 221149).
Then you are on the right track.
 

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Is this normal? Should I expect soot level to become more stable over time?
I imagine your fuel trim(s) will slowly adjust to the change in airflow (after cleaning). So its possible the soot accumulation will become more consistent.
 
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