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2010 Forester Diesel 6sp Manual
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1) auch..
2) i have seen such distances on mine during summer when my original DPF was in place. Didn't had any leaks back then
4) i did home DPF flushing ritual with muriatic acid. after 100km cyclic regen kicked in and I was at 50% soot. Second regen was at 600km, now I am close to 600km and with 56% soot again. And that's with used DPF with unknown history and condition.
5) maybe try monitoring expected and real intake air mass. Not air flow(maf) i recently had maf problems (at least I hope it was MAF sensor), where real air mass was reading 3x more than expected and results were lots of EGR angle to keep fresh air mass low and running rich since - hey "theres lots of air, lets dump fuel accordingly"
 

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Discussion Starter · #402 ·
Dieselforry,

2) Thanks. Yes always was a reduced distance in summer, but usually around 300km.
4) I had something similar after a forced regen. A good distance a couple of times then suddenly a 100km or so distance with a constantly increasing soot reading no matter what type of driving or differential pressure followed by better regen distances again... I wonder if that was a cyclic regen, or some sort of other calibration regen.
5) MAF was cleaned at/before forced regen, checked with a Subaru diesel specialist and it was returning the correct reading at idle. May need to check again.
 

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Rescuing an Overfull (limp mode) DPF
I've recently managed to drag back an overfull DPF (>135%, the cutoff for a forced regen and activation of limp mode) to a workable state. Whether the DPF has been permanently damaged or is otherwise not reasonable workable I'm not sure yet as haven't put enough klms on it. The following is a brief synopsis of the situation, items required, techniques/theory used and the results/resolution.

If I get a chance I'll firstly post some screen grabs. After that if I really get a chance I'll write up a separate thread outlining a particular situation, what is required and how to proceed to 'rescue' the DPF.

Situation:
Overfull DPF (>135%) causing limp mode and preventing forced regens.
  • Situation caused by interminable peak-hour city driving with no relief for the poor vehicle
  • Soot level at one stage read 255%. I didn't believe it at fitrst- the believed it was likely higher but 255 is the max value for an 8-bit integer (!)
  • Car was still running OK though
Note Oil dilution and Ash levels were 0%- caused (I assume) by repeated dealer DPF resets when they previously executed forced regens (may have had to 'simulate' a new DPF to force the regen).

Items Used
  • Penrite Enviro+ DPF cleaner (fuel additive)
  • OBD-II Bluetooth dongle and Torque Pro on Android (for easy logging/display)
  • ECUTEK ProECU Tool (on Win 10 laptop)
  • Freeway with some extended/consistent hill climbs and suitable (hot) weather
  • Some loading for the car (in this case, approx 6 x 25kg sand bags) + electrical accessory loading
Techniques/theory
  • Utilise passive regen to get the soot <135% to allow a forced regen
  • Passive regen occurs/starts around 400C esp. when assisted by a DPF cleaner additive. DPF Temps >400C (under normal running) in the Forester require some load and uphill running in warm/hot conditions
  • The soot levels can be cross-checked against the DPF differential pressure
  • Once soot <135%, use ECUTEK tool to initiate forced regen
  • Once forced regen finished, check running of the car.
  • If soot cannot be brought <135% to initiate a forced regen, 'install a new' DPF (i.e. tell the car a new one's been installed) and then force the regen
  • Another alternative is to disconnect the DPF pressure pipes at the differential pressure sensor to allow the computer to rescale the soot itself (based on 0 differential pressure) before forcing a regen.
Results/Outcomes
Basically, the (pretty well) terminal soot loading was reduced to zero. All error codes cleared, car returned to 'normal' driving.
  • Soot started at 255+% in Sydney.
  • Drive to Canberra using the DPF cleaner additive reduced soot level to ~192%.
  • Note soot level firstly rose rapidly on the drive out of Canberra to the freeway hills, touching ~240%. Unloaded Forester driven up & down hills on the freeway. Before cooler weather intervened (and the DPF temp wouldn't get to 400C) the soot briefly touched a min of 130%. Returned home, soot at ~162%. Note car in limp mode limiting fuel, boost, revs but also soot production. DPF pressures ~3-4 kPa at idle, ~14-18 kPa whilst cruising and ~50+kPa worst-case accel.
  • Some extra DPF cleaner additive added plus some fuel (to bring to additive to 'cleaning' concentration) Forester loaded with sandbags (approx 150kg) and then driven in hot weather (36C) up & down hills on freeway. Extra load added through max A/C, max fan, rear demist and headlights. Again rapid soot increase to ~225% on way out. After that, at one point soot reduced to ~70%. Toilet break with soot at 90% resulted in car restarting out of limp mode- and soot back to 152% by time freeway speed was reached! Back into limp mode, more uphill runs and eventually returned home with soot starting at 90% and not climbing above ~96%. DPF pressures ~2-3 kPa at idle, 10-14 kPa whilst cruising and ~20+kPa worst-case accel.
  • Forced regen initiated in driveway using ECUTEK ProScan. Extra cooling provided through small industrial fan placed at front of car. Forced regen completes in only about 15 min. Shows minimal oil dilution (<0.5%) and soot reading showing 0%. at the end. Cool car by idling for 4-5 mins, soot then shows ~5%.
  • Drive a bit next day (e.g. to return sand bags, go to work). Driving mostly suburban and gentle highway cruising. Soot rises to 30% over approx 100km (max). DPF pressures ~0 kPa at idle, 2-3 kPa whilst cruising and ~20+kPa worst-case accel (no limp mode).
  • (Additional info) No DPF reinstall/reset/reinitialise needed, nor manipulation of DPF pressure has been required...yet! :)
You are right! The fact that I did read the whole sorry story of how to run a car...I feel your pain as i have problems with OB 2014. I have become literate in DPF issues. I am off driving around 200 km highway + or - tomorrow. Wish me luck!

..get a new car!!!
 

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2010 Forester Diesel 6MT
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Discussion Starter · #404 ·
Just for your entertainment, if not mine, the "hill holder" lamp came on the other day- vanished again after a couple of restarts. I did pump the brake pedal in between just in case there was an issue there (I beleive the hill holder works with the brake system) so not sure if that had anything to do with it. Maybe there's a loose connector, maybe it's starting to need recalibration, maybe a component's failing, maybe it was unhappy no other lights were on, I don't know.
 

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Hello! New in this forum! Thank you very much for all the comments and excellent discussion.
I bought a second hand forester 2016 CVT with 90.000km, ash was at 30%. The previous owner had around 140 successful regens and 240 attemps (60% success roughly)

I have done 6.000km
with it and it is doing what you described, regens occur very often when driving on the motorway. I am able to do 70-110 km (at maximum) between regen cycles under regular driving (CVT in D mode, 2300-2400 rpm, 130-135 km/h). Yesterday, on a 480km non-stop trip I was able to get 180km between 2 regens by driving the CVT in 6th "gear" most of the time between 2600-2800rpm.
If I drive above 3000-3200rpm in 5th gear, soot increases. I guess the increase in fuel outweights the ability of the car to burn the soot.

Things I did last month:
  • Took the car to subaru (30% ash) with 93.000km because I was noticing too frequent regens. They forced a DPF regen and added a liquid to the tank. I had NO lights/errors in the dash but they thought that doing that was a good idea. They reset the ECU so ash and soot displayed 0% (after 3.000km ash has risen to 1%). It did not improve and they suggest to replace DPF (but that is my last option).
  • Took the car afterwards to a private garage. They dismounted the DPF and cleaned it by using water pressure systems and some decarbonizer. This was 1600 km ago but I have not seen any difference. Of note, they did NOT reset the ECU, it was only 100km after subaru cleaned the DPF and reset it. Not sure if this is relevant.

Things I did last week:
I changed oil 1000 km ago. Then, I cleaned the MAF sensor, the differential pressure sensor and checked the intercooler hose. I previously added a liqui moly injector cleaner but did not improve.

My next steps after reading you guys:
  • Do a throttle relearn
  • Check air filter, though it was changed 6.000km ago.
  • Check the MAP sensor. I tried last week but could not dismount it due to the reduced space to work with the tool.
  • Buy Xenum in/out which is much stronger than liqui moly (and expensive) and see if the car improves with it.
  • Clean EGR? I don´t have the knowledge/tools to do that. Any liquid that you recommend, or taking the car to a garage?

Other things I have noticed:
My coolant temperature is around 82-85 celsius degrees most of the times when driving on the motorway (not towing). When iddle, or driving uphill at low speeds can get above 90. Is this normal?
My soot levels behave as long as the estimated DPF temperature moves above 320 degrees or so.
When my car does a regen soot drops to 0%, but now it drops more slowly than before the cleaning.

Thanks!
 

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Hi and welcome!
You did a very good job formating your post, it was a pleasure to read :)
For us to judge whats normal and whats not it would be good if you'd mention your mileage, ASH % and regen count, so we could compare that to different cases and compare how is (or isn't) yours different. Also is your engine Euro5 or Euro6?

as for driving 6th and 5th gears, I have noticed that higher rpm in the same speed increases soot %, I am not sure that engine really generates more soot thus clogging the dpf, or its just how it calculates soot buildup (more rpm - more air mass, more fuel)
Yesterday, on a 480km non-stop trip I was able to get 180km between 2 regens by driving the CVT in 6th "gear" most of the time between 2600-2800rpm.
Thats probably because EGR starts to close from 2600rpm and is closed above 2800rpm so you were right on the edge of its operation. Myself and other members can confirm that EGR has a huge impact on DPF behaviour.
I previously added a liqui moly injector cleaner but did not improve.
I have done it too wothout results.
Do a throttle relearn
dont know what you think of that, but doubt that will make a difference.
Check the MAP sensor. I tried last week but could not dismount it due to the reduced space to work with the tool.
I did mine with this tool:
550742

Buy Xenum in/out which is much stronger than liqui moly (and expensive) and see if the car improves with it.
dont, won't do anything. Maybe try adding some DPF additives in fuel tank. Liqui moly have them.
Clean EGR?
Do this instead of injector cleaning. nothing too complicated.
My coolant temperature is around 82-85 celsius degrees
If im not mistaking, OEM thermostat is 82*C, so your temps are good.

The best thing would be taking your DPF to DPF cleaners to flush out all the soot and ash, then reinstall it, reset its parameters and forget about it for a while.
 

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Thanks DieselForry. I have EDITED my previous comment and added important information that you mentioned (ash, mileage, things I did last month - DPF cleaning), etc. I have underlined the new information.

I tried with that tool to clean the MAP but I have no space, maybe mine is larger?
I read that throttle relearn helps the response to be better pressing less the pedal. I have to press the throttle quite a lot and thought that it could help.
Will clean EGR, thank you!
A colleague with a Suvaru XV has his coolant temperature at 90 degrees. That´s why I asked. I just wanted to make sure that 82 was fine and that was not the problem of the DPF regens.

Thank you!!
 

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Id say your Subaru behaves like any other Subaru in summertime. Why summer? many have reported that warm weather has a negative impact on soot behaviour(different fuel, more EGR). When I bought mine in winter I got around 500km between regens and in the summer it dropped down to like 100km and thats when I decided it is time to remove it, since I thought somethings wrong, turns out, it is considered ''normal'' in Subaru diesel world. I also tried injector cleaning, intake cleaning, sensor cleaning. Blocking EGR resulted in doubling distance between regens, but threw a check engine light from time to time. Now I know it can be closed by a ECU remap. Drove around like that (without DPF) for a while and last november I reinstalled a used DPF that I flushed at home. since then my average regens are back to 500km (i had distances between regens from 200km to 1000km). Now warm weather comes and I'll see how it behaves now.
 

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Thanks DieselForry. Well, I live south Spain and we have around 20-24 degrees now during the day. I saw yesterday 27 degrees on the road. Not sure what will happen when it reaches 40 degrees then...
I am going to check air filter and try to clean the MAP and EGR. I don´t know of people in Spain remapping the EGR so it stays closed. I have seen they sell the EGR blanking plate, but I need to read more about it and learn where it has to be installed and if it is safe or needs ECU remapping too.
Another thing I have seen when comparing my forester with the XV of a colleague is that in my case, 4 to 5 regens increase oil dilution by 1%. In his case, 1 regen increases it by 0,7-0,8%. My car regens so many times that I don´t see oil dilution dropping, but he does.
 

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So welcome in Subaru diesel summer hell. I sent my DPF for cleaning to specialized company last autumn. But as the weather here is still quite cold, Slovakia, so I had only 3 regeneration till today. And 1st was forced after DPF cleaning. For now I have more than 2800km from last regeneration. But this will dramatically change when temperatures go up, for sure. So actually I can't say if DPF cleaning made any difference at warm temperatures. Most probably not, but I will see. For example 2 years ago I made a road trip from Slovakia to Corsica. When I started it wasn't hot outside and regeneration distancewas was more or less ok, but in Italy was quite hot and regeneration distance shorten to 80-100km. So hot air means less oxygen in the same volume so burning is getting worse and that is probably the reason of shortening the regeneration distances... or at least one of them... I think that there is nothing wrong with your car. Other car makers has similar problems, but maybe not that obvious as Subaru. Subaru diesel likes winter

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Thanks svkforester!
I should not be worried then, but I have colleagues with subaru in Madrid and they do 400km between regens now, less during summer time.
I just took out the MAP sensor and looked very dirty. I attach pictures of before and after cleaning.
I also checked the air filter and it looks a bit dirty but no so much I think (pics attached too). It has 6,000km on it. Will use compressed air later on as I don´t think it should be changed.

Do you think that if I use another type of air filter (more breathable) could improve the FAP´s way of working?
Thanks!
 

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Welcome @Subnotsuv , nice car . About DPF is already confirmed by others that it doesn't like the summer. I have the same engine, not the same car , but is Outback bought from Madrid at 143k km and had like 350 attempts of regen and more than 250 succeded so also like 400km between . I have now almost 180k km but did a clean and resset the values and have now like 60 with 50 succeeded, so again more or less than 500km. Here in Romania is more colder than Spain but also in the summer i rarely see over 250km between regenerations. The only viable solution i have seen was presented by @ptr123 by blocking the EGR from software. Now he had like 3k km between DPF regen .... Good luck!
 

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Thank you @Sorin003 . Yes, I think that seems the best solution too. I just want to clean it before and see how it works, since a high proportion of my annual driving is long trips on the motorway.
How do you guys block the EGR from software? Is this detectable when going through the annual/national test/check mandatory in each country?
Thanks!
 

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I found video about throttle relearn/calibration. I guess it was made on dodge but works on subaru either.
I tried on my subaru outback 2012 diesel, and car felt different. Acceleration was much better. Mine is mechanical but acceleration became better from low revs.
It is simple you just have to turn the ignition on (dont start the car) then press acceleration pedal way to the floor and wait 15-20 seconds, then turn the ignition off and release the pedal. Sometimes I do it twice in a row, wait for two minutes and give it a try.
Of note, I tried this in my forester 2016 and did not work. Tried twice.
 

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Blocking EGR with a remap won't be detected by any inspection unless they measure NOx content in exhaust (I'm 99% sure they don't).
EGR is used during regens, so blocking it a blanking plate could somehow interfere with the result, but I had mine blocked for a while, didn't see any problems.
I think any remap, chip-tuning shop could do it.
If you have obd reader and you can erase codes and clear check engine light,get yourself a blanking plate and try it out.
 

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Thanks DieselForry. Yes that can be a starting solution. I have obd scan which allows me to clear codes. I will try and buy a blanking plate, will check on google. Can you recommend one?
I attach a picture with some graphs after cleaning the MAP sensor. It is just a 5 min drive around the village today (iddling and also at low speeds, up to 75 km/h or so). Can you see any wrong data?
Thank you so much guys, you are so helpful!!
 

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Can you recommend one?
I made mine out of random peace of steel plate laying around. I removed egr gasket, traced around and marked holes and cut it with angle grinder, installed and boom, done.
Can you see any wrong data?
I think everything is fine. But do you really monitor target manifold pressure? Target pressure without compared to actual is pretty much useless. Or you should just monitor actual intake pressure.
 

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I made mine out of random peace of steel plate laying around. I removed egr gasket, traced around and marked holes and cut it with angle grinder, installed and boom, done.

I think everything is fine. But do you really monitor target manifold pressure? Target pressure without compared to actual is pretty much useless. Or you should just monitor actual intake pressure.
So you cover the whole of the EGR completely, right? Will try that. My guess is: if the EGR is completely blocked and therefore I understand the readings are 0, will the DPF know when to regenerate?

Regarding the manifold pressure, yes you are right, my fault. I have now chosen in the app the one I believe reflects the MAP reading, and not the target.
Thanks!
 

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EGR will operate as usual, but because it will be blocked by the plate ECU will detect a missing portion of air from EGR and you will get error from time to time.

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