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The great DPF myth

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  • this is a view of front, back and cross section of catalyst

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    • front and back of actual particulate filter

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      • As you can see it is just a physical trap.
        Made up of porous square tube that has every second square section blocked on opposite end.

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        • dandin
          dandin commented
          Editing a comment
          I'm surprised the engine makes any power having a restrictor like that in the exhaust. Great informative post as always.

        • Spook1205
          Spook1205 commented
          Editing a comment
          Thanks Dandin 🙂
          It’s really a strange construction and material type. Almost like a crushed glass substance.
          Initially I thought how the hell does exhaust flow through this, but you can blow through section with ease.
          So it’s realy quite porouse and a huge surface area.

          To me it shows most blockage failure is really due to lack of heat from catalyst, which can be numerous reasons but that’s another discussion.

      • ok , so are the gases are forced to do a 180deg turn back on themselves before going through the porous walls or are they forced through the porous walls under pressure?
        2016 GX , in White

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        • Spook1205
          Spook1205 commented
          Editing a comment
          Forced through porous walls down the length of the square tube into adjoining sections. No 180 turn around.
          I was surprised how easily it was to blow through a section of it.

        • Silverfox1111
          Silverfox1111 commented
          Editing a comment
          So spook1205, do you think the dpf is a performance limiter in the exhaust or does it flow enough to get power gains if a ecu tune is done?
          Silverfox

        • Spook1205
          Spook1205 commented
          Editing a comment
          That’s a tough one Silverfox because it depends on what type of power gains you are after.
          Any restrictions that reduce its ability to breath is a performance limiter.
          If I was after a tweak of extra power without affecting reliability that much I would leave it in. If after decent power gains it would be gone.

      • Always good to get pics & info explained in simple language, so non mechanical types like me can get an idea of these things.

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        • I just had my first DPF burn since getting the latest DPF campaign ECU reflash. The dealer at Werribee Toyota failed at enabling Custom Mode... but that's another story.

          The biggest difference I noticed, it was over within a 10km drive in suburbia (lots of stop start in 50-60km zones). The DPF% got to as low as 4% after the burn. It would normally take much longer than this and generally DPF% only got as low as 8%.

          I didn't see much difference in temps but I'd been keen to see what the temps would be like during a burn on a freeway. I think it would also result in lower DPF%.

          I didn't monitor what the 5th injector was doing during the burn, I forgot to do it in the excitement lol.

          I think the new programming is a good thing. +1 for Toyota for releasing this update.



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          • Spook1205
            Spook1205 commented
            Editing a comment
            Burning out to 4% would have to be a good thing plus getting it over with by 10km means it doesn’t have to re heat again. I have read that lots of unfinished burns isn’t good.
            Good to hear you think Toyota have done a good job on this, let’s hope they have finally nailed it.
            Did you have issues before? Or need to force a burn?

          • dandin
            dandin commented
            Editing a comment
            No issues before the update and I've never forced a burn (except for the few times to test the manual DPF burn button in Torque Pro). I noticed if the DPF burn has just started and I've been stopped at a set of lights for a while I would get some white smoke out of the exhaust. It would immediately go away once I got up to speed so it was never anything of concern.

          • Spook1205
            Spook1205 commented
            Editing a comment
            Nice one!
            Hopefully I’ll get around to getting the newest update soon

            Cheers

        • Just returned from a 5000 km trip to the NT via western Qld. ECU update carried out before trip so plenty of time to observe its performance on the scangauge.

          Basically:
          1. Around 250 km between regens however this varied around fuel use. ( at highway speed)
          2. Regens took around 25 km to complete at highway speed.
          3. Peak burn temp around 750 degrees cent.
          4. Noticed that 5th injector working when stopped, not sure when travelling at speed though.
          5. Can notice a slight increase in fuel use during the burn on the Toyota Eco app.
          6. Travelling at 105km/hr, fuel use consistently around 8.3 ltr/ 100 km, under ideal conditions.
          7. Pushing into a headwind increases the fuel use and engine cannot hold 6th gear.

          Hope this is useful. I'm quite pleased with the ecu update.

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          • Well I glad that most people are pleased with this update, as a Prado owner I have to wait until an update is announced for our vehicles and I am looking forward to comparing before and after with Techstream recordings.
            I know that I am a miserable old cynic but I still wonder what this update does, for instance the two posts above seem to contradict each other, if the burn is over in 10 Km in suburbia then that must be considered a big improvement but as Snapper has reported burns every 250 km lasting around 25 km at highway speeds then the frequency has increased, (mine is 300-350 Km pre update) yet the distance covered during a burn hasn't changed much at all. Surely this would cause increased fuel consumption overall?
            Anyway I hope you Fortuner owners don't mind me making comments about the DPF on here but there is much more discussion on this forum about the DPF than on the Prado one.

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            • dandin
              dandin commented
              Editing a comment
              Of course you're welcome here.

              Regards your statement of contradicting posts, I found (even before the DPF update) that freeway burns have always taken longer than suburbia burns.

            • Spook1205
              Spook1205 commented
              Editing a comment
              I have the newest old update from a few months ago and it definitely burns hotter. Get about 330 to 350 between regens but every few it chucks in 1 or 2 regens after 100 odd kms.
              I would think less fuel would be used to go hotter for shorter period of time. Especially if you are taking away 30km of highway regen.
              Keen to see more of the newest one and of the Prado changes

            • dandin
              dandin commented
              Editing a comment
              Just another thing to add, it took 330km to do the first burn since the ECU update. Like you, mine normally does a burn every 300-350km

          • I’ve been to Melbourne and back (from Sydney) after the latest update.

            I noticed on the last burn that the DPF% got down to 0%, which I assume is a very good thing.

            Regarding Custom Mode, I was expecting a flashing symbol on my GX during regens as per the information sheet, but what I get is a message on the MID saying DPF REGENERATION IN PROCESS. The message appears briefly at the start of each burn and then disappears. It would be easy to miss if you weren’t monitoring with a ScanGauge or the like.
            2015 GX auto / Genuine steel bull bar, snorkel and tow package / Ultimate suspension / Rhino sliders / BFG KO2s / ORS drawers ...

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            • With the above info from Dandin and mrh460 I am wondering if the newest update has same regen parameters as the last one.
              difference being newest
              - is a planned rollout
              - has option for custom dash display
              ​​​​​​- has superburn forced regen for the mechanics to run it through after update to make sure it’s clean.

              does this sound feasible?
              Would they again change regen parameters so quickly after last update came out after a lot of R&D and testing?

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              • I managed to catch the DPF ratio go from some random high value to it's correct value yesterday. I know several members have reported this before and I've seen it several times during my ~3 years of ownership but it's the first time I managed to catch it whilst logging the outputs from Torque.

                I've had the latest DPF recall done (campaign ID LGG71) and just finished one of it's burns from the previous drive. The next time I drive it I see that DPF ratio is over 60%. I knew it wasn't right because it just did a burn about 30-50km ago. So, I started logging and eventually it corrected itself.

                I've attached the log output and a chart for the nerds.
                Attached Files

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                • JohnLynn
                  JohnLynn commented
                  Editing a comment
                  Thanks for posting the chart of the recalculation happening, although I like to think that I have an enquiring mind and wont be fobbed off rather than being a nerd!
                  Anyway I am pleased that others report the "recalculation" happening which my service manager says does not.
                  It is interesting that your graph shows a sharp drop initially as I have only ever seen a gradual fall. The mystery (to me) remains, why does this occur? is the ECU plotting the rise in % blockage from an algorithm then re-assessing what has actually happened from the current driving conditions and re-adjusting accordingly? or am I just reading too much into it? to sum up WTF lol

                • dandin
                  dandin commented
                  Editing a comment
                  The two "nerds" I thought who'd reply, have replied. My day is complete :-)

                  I've had 2 DPF burn cycles and about just over 1000km since the DPF update. My fuel economy has improved, it's currently sitting at 8.5L/100km. I think the DPF burn cycles being a lot shorter has a lot to do with it. The last burn took 7 minutes!

                • Spook1205
                  Spook1205 commented
                  Editing a comment
                  Dandin you just made my day👍
                  John I share your thoughts on this and to me it makes sense. It has the pressure sensor to monitor build up and if it’s not got to to expected cautious algorithm it can re adjust.
                  Again this is just a theory.

              • Just had my first burn since the update today. Extra-urban driving in Canberra (80-100kph), took about 25kms to complete which feels a little faster, temps looked same as always. Unfortunately Toyota failed to do the custom mode despite being asked, as there was no indicator on the dash

                Dave

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                • mrh460
                  mrh460 commented
                  Editing a comment
                  I’ve had Custom Mode installed for a few weeks now, and on my GX it does not operate as set out on the pamphlet.

                  Rather than getting a flashing DPF light during a burn, I get a brief message DPF REGENERATION IN PROCESS on the MID at the start of each burn. It's very easy to miss.

              • BTW, does anyone know what a 'superburn' is? It was written on the worksheet along with the ECU update. Is it just a regular manual burn or do they use cleaner or something?

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                • Spook1205
                  Spook1205 commented
                  Editing a comment
                  It’s done in the workshop at time of update. Not something we get to use.
                  Can only presume it’s a very hot burn to make sure it’s cleaned out.

              • Anyone done or doing extended highway driving with new tune?
                slowly more info is popping up about holding the accumulation % at a level on highway with a passive burn. Which is an awesome update and is better than having 3 burns in a day lasting for a total of over 200 kms when towing long distance.
                I mentioned this back in November but was towing a van. But will it do it with no load?

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                • From what I was told when I picked up the car, its hooked up to a machine & takes about 6 hrs to perform the workshop burn, & when they start it, they must see the job through. Apparently they can't stop it mid stream then kick it off again. I believe chemicals or additives may have also been used at the time, but not 100% sure.

                  per mrh460s comment, I've only noticed the DPF regen message once, even though I look for it.

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                  • gbrought
                    gbrought commented
                    Editing a comment
                    Just completed my first (regular) Syd-Canberra-Syd run of 2019 since the latest update / tune (just before Christmas). I can't offer any diagnostics but can report noticeable improvement in fuel economy: im guessing at least a litre/100km less - maybe even 1.5 less!!
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