GBMUD Posted January 18, 2012 Share Posted January 18, 2012 Someone is bound to ask; a DPF is a Diesel Particulate Filter, part of a diesel exhaust system prone to blocking on cars that spend a lot of time round town. When it does block the engine goes into limp mode or may decline to start altogether and the main dealer gets another cheque. So, can one disable a DPF? Poke a hole through it or something? Would it fail an MOT - outwardly it would look like an unmolested DPF. Or, as some people do with Cats, even fit a de-DPF'd pipe and just screw the pressure sensors into two bosses on the new pipe? Any thoughts or comments? Chris Quote Link to comment Share on other sites More sharing options...
Orgasmic Farmer Posted January 18, 2012 Share Posted January 18, 2012 Talk to Steve. He is a bit of a whizz on them! Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted January 18, 2012 Share Posted January 18, 2012 You can just cut the filter out of it's casing and re it the casing but the engine management system can tell. The ecu looks at the pressure differential between the before and after the dpf. The ecu will have a stored value for a new clean filter any less and it'll throw a code. Quote Link to comment Share on other sites More sharing options...
muddy Posted January 18, 2012 Share Posted January 18, 2012 Most cars have a regeneration setting where it basicly revs the tits off itself for 20 mins or so, but if the dpf is too far gone it will not start this process, heating the whole thing up with a propane torch or bottles can often trick it into thinking its low enough to start the re gen cycle, although manipulating a dpf thats red hot back to an exhaust is 'fun' Will. Quote Link to comment Share on other sites More sharing options...
Orgasmic Farmer Posted January 18, 2012 Share Posted January 18, 2012 http://www.lion-garage.com/diesel-particulate-filters/ Quote Link to comment Share on other sites More sharing options...
GBMUD Posted January 18, 2012 Author Share Posted January 18, 2012 You can just cut the filter out of it's casing and re it the casing but the engine management system can tell. The ecu looks at the pressure differential between the before and after the dpf. The ecu will have a stored value for a new clean filter any less and it'll throw a code. Could one simply fool the ECU with a resistor in line with a sensor? I suppose that the ideal might be if one were able to force the regeneration manually but I gather that this is a dealer only option. With an eye to the future, I am wondering if Defenders with DPFs are likely to be a problem in the future as many may never go far enough or fast enough to reach the required conditions to regenerate the DPF. Chris Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted January 18, 2012 Share Posted January 18, 2012 The required conditions on a defender are just a steep hill surely? It's not about speed but more about exhaust gas temperature which is related to engine load and fueling, isn't it? Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted January 18, 2012 Share Posted January 18, 2012 You could fool the ecu with a resistor, Any garage with decent diagnostic equipment should be able to regenerate your dpf. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted January 18, 2012 Share Posted January 18, 2012 Can a DPF only take a certain number of regens? Will the honeycomb structure eventually burn up? Quote Link to comment Share on other sites More sharing options...
steve200TDi Posted January 19, 2012 Share Posted January 19, 2012 I thought when the pressure difference gets to a certain limit it either regens automatically or it will give a warning and you need to pull over onto the side of the road and it will commence its regen. Or take it for a plast up the motorway once a month to clear it out? Steve Quote Link to comment Share on other sites More sharing options...
jai_landrover Posted January 19, 2012 Share Posted January 19, 2012 My company passat had one it got blocked. It tried to regenerate it didn't work. regeneration is somthing like sit at 3000RPM for longer than 20 miles. I did this but it was too far gone £1900 quid later main dealer another was fitted. Another good reason not to buy a new car. Yes some people punch them through but the ecu can tell tho. They are a legal requirement well since 2007 on diesels to filter the exhaust. and thus emit less emissions. All pointless and another waste of dosh. There is a huge thing on the net where many londoners are taking VW to court as the car was missold to them living in London and always being in traffic the EGT never gets hot enough to burn off the collected waste. Not fit for purpose or somthing like that. Spending £20K rebuilding an early defender or RRC with a tdi seems more and more favourable as an everyday motor as they roll out p;lenty of these silly little rules and regulations.. Quote Link to comment Share on other sites More sharing options...
pat_pending Posted January 19, 2012 Share Posted January 19, 2012 Suzuki had to withdraw Diesel Grand Vitara's from the Chanell Isles and the Isle of Man because they couldn't get DPF's to regenerate. Whilst some models seem to have endless problems with DPFs, others are trouble free. Depends how the manufacturer has programed the engine managment software. Many of the faults we had with early Grand vitara's seem to be sorted now. It's still recent technology, the bugs are being sorted and unfortunately it's the future, like it or not. As to fooling an ECU after you've removed the DPF, good luck. the managment systems know exactly what is going on. Not saying it couldn't be done, but the effort would probably outweigh any gain. Quote Link to comment Share on other sites More sharing options...
Steve 90 Posted January 20, 2012 Share Posted January 20, 2012 You could fool the ecu with a resistor, On most systems you can not fool the ECU with a resistor. The differential pressure sensor will be looking for a different back pressure (or difference across the filter) for different air flow/engine load and time conditions. For example, If you have driven at 75% engine load and 80% throttle for 2500ms it knows what the differential pressure should be and that it will be different for any variation in engine condition. It has a MAP in the ECU that will cross reference all the engine load sensor readings against feedback from the differential pressure sensor and flag a fault if it’s outside of tolerance. So a constant value will flag a fault code for an implausible signal from differential sensor and the ECU will default to limited operational strategy. If you remove the filter without writing it out of the software it will see too low a differential pressure and again flag a code and default to LOS. Basically the system is pretty clever and will know if you remove the filter the same as it knows when it’s over loaded. Most systems can have it written out. Never failed yet with a Bosch, most the others are removable about 90% of the time but would need to read the software before being certain. Some of the Jap stuff (Mazda 6 etc) can be tricky but I think we’ve probably cracked that now. A lot of performance tunes have to be limited when a DPF is present so a lot get removed for that reason. Any garage with decent diagnostic equipment should be able to regenerate your dpf. Trouble is, very few have decent diagnostic equipment and even less have a clue what they are doing or how the system works. We do Diagnostic work for pretty much every garage and a few dealerships in our area, The level of skill and understanding in 80% of the trade is (I am ashamed to say) very poor. HTH Steve. Quote Link to comment Share on other sites More sharing options...
Steve 90 Posted January 20, 2012 Share Posted January 20, 2012 Can a DPF only take a certain number of regens? Will the honeycomb structure eventually burn up? They will reach a limit yes. Assuming the system has been operating correctly (a lot will not re generate if there are any fault codes stored, DPF related or not) , some PSA stuff (peugeot and Citroen) was about 80,000 miles. VAG seem to go a little longer. We do now have a gel from Germany that we soak through the filter overnight and steam clean out the following day. That does extend the life a little. But, they will eventually get to the point where they need replacment. Steve. Quote Link to comment Share on other sites More sharing options...
Steve 90 Posted January 20, 2012 Share Posted January 20, 2012 My company passat had one it got blocked. It tried to regenerate it didn't work. regeneration is somthing like sit at 3000RPM for longer than 20 miles. I did this but it was too far gone £1900 quid later main dealer another was fitted. Another good reason not to buy a new car. VAS (the VAG dealership tool) will not allow the system to regenerate at anything above 90% ash mass. I have done them for people that have been told by VAG that they need an expensive replacment many times. After checking everything is OK with the system, I have forced regeneration at 150% ash mass, but would only do that on the road as the heat would be scary when stationary. If that fails we soak and wash them through and re try. As said above, We do a lot of stuff for other garages including sort stuff that the dealer has failed to fix. Steve. Quote Link to comment Share on other sites More sharing options...
discomikey Posted January 20, 2012 Share Posted January 20, 2012 our disco 4 tells us that every now and then, we need to take it on a good hard thrash to clean out the DPF thats it no dealers. Quote Link to comment Share on other sites More sharing options...
GBMUD Posted January 20, 2012 Author Share Posted January 20, 2012 Thanks for the input Steve, lots of detail there! Getting a warning that a good thrash is needed is a great thing but is not always an option. I was thinking about Defenders of the future, and how I have used mine. Mostly, like most people, I use it on the road but I have been to more unusual places. What if one were half way across the Atlas mountains, or crossing dunes somewhere for example when the DPF decided it was blocked up? High altitude (and potentially poor fuel) tends to make for smoky diesels so I assume that the DPF will block sooner but if going faster than about 30mph absolute max for more than a few seconds is not an option, what can one do? The answer must be to remove the DPF - by one means or another. Chris Quote Link to comment Share on other sites More sharing options...
reb78 Posted January 20, 2012 Share Posted January 20, 2012 Legalities of removing one aside (i'm sure it will become part of an MOT/law that they cant be removed), would it not be possible to design a silencer of sorts that replicates the flow resrtiction caused by a DPF in perfect condition? That way, you have something that wont block up, but will fool the sensors into thinking that all is fine. Other silencers could be removed further down the system perhaps to make up for the addition of an extra one? (the DPF and the expense of replacement was one of the things that put me off of the new defender) Quote Link to comment Share on other sites More sharing options...
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