what is this DPF thing all about? and what to look out for?

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  • what is this DPF thing all about? and what to look out for?
  • stumpy01
    Member

    diesel particulate filter in the exhaust. I think it catches all the large bits of soot and burns them off.
    Problems arise if the dpf can’t get hot enough to burn off the soot, so the whole thing clogs up. I think this occurs mainly if you do lots of short journies. I don’t know what a ‘short’ journey is, but imagine that doing 10 miles+ fairly often and giving in the beans once in a while should keep things ticking over.

    I think they are expensive to replace, but dunno how much. My OH has just got a new diesel Ibiza (2.0 TDi) and that has got one in it, so we’ll probably find out at some point!

    I think if buying a second hand car, issues with the dpf are more likely to be on low mileage cars.

    M6TTF
    Member

    echo as above – as long you’re doing reasonable miles each day, or give it a good motorway/dual carriageway run once a week you ‘should’ be fine. lots of VAG cars suffering with issues though, which put me off when buying

    adi66
    Member

    DPF = Diesel Particulate Filter

    Here comes the science bit… lol

    It basically stops all of the soot escaping from your exhaust (Hence modern diesel cars don’t have black smoke anymore) The DPF is like a section of honeycombe, but with alternate tibes blocked at each end…. as you drive the “tubes” fill with the soot, when they are full enough to change the back pressure of the exhaust system (DPF canninster section) the EMS of the car will trigger a re-gen activity, that will force the exhaust (By either using more fuel or a addative (that is stored in a little tank on the car), such a Sirium (French cars use this a lot)to burn hotter, effectivly burning the trapped soot particles into “finer/ smaller particles” that can then pass through the porus wall of the DPF brick, and escape through the open end of the “tube” (remember the alternate open / closed end tubes on the face of the DPF Brick…)

    All this will happen automatically, and at set throttle positions, engine and wheel speeds – so ususlly when your doing >60 mph and over 1,800 RPM, so read that as: Motorway Speed.

    There are problems with all systems but as long as there is no “emission lamp” on the instrument cluster, you should be ok. And if the car uses Sirium, do your homwwork, and check when it was last serviced / filled, as its about £70 a litre !

    Blocked DPF = rubbish peformance and economy, and is BAD for your engine in general.

    Premier Icon bails
    Subscriber

    The 1.8TDCi Ford engine (fitted around 2005) doesn’t have a DPF, if that’s any help.

    Premier Icon cp
    Subscriber

    Hence modern diesel cars don’t have black smoke anymore

    oh they do.

    Sui
    Member

    AS above Diesel PArticulate Filter. There is in theory no reason why they cannot last 150-200K miles on a car, however it is largely dependant on the type of driving you do (it also effects the oil in your car).

    If you are a constant “town driver” using the car for multiples of short journeys, then the *regeneration process never gets a chance to kick in

    *Regeneration, is where extra diesel is put into the DPF and the temp of the exhaust system ignites the diesel “burning off” the deposits that the Filter has collected. The Regen cycle can only be performed in optimum conditions – these are Hot exhaust and constant running rate, this loosely translates into 20mins on the motorway/A road above 2000rpm.

    If the regen process never gets a chance to kick in, then the DPF will clog, then eventually fail. Another side effect, is that the waste diesel from the failed regen cycles gets dumped into the oil sump. The bad thing here is that the oil will then be diluted by diesel and cause premature wear on the car and will nesseitate frequent oil changes as well (expensive).

    So, if you at least get a motorway run every 200-300 miles then you should be fine, if not DPF’s are a nightmare.

    The above is the reason there is such a debate over running costs of diesel vs petrol. My journeys are all motorway, so i am always getting good regen on the DPF, this means that my oil also last longer between services, and i get less overall wear on the engine.

    edit – too slow 🙁

    adi66
    Member

    Member

    Hence modern diesel cars don’t have black smoke anymore

    oh they do.

    When they re-gen, or your REALLY boot it they do…. but not anywhere near as much as a “old diesel” !

    Sui
    Member

    adi66 – do you work for Ford (not many people know about Sirium)

    maxtorque
    Member

    It’s worth noting that you do generally have an early warning system, that indicates with a lamp on the dash that the DPF is becoming blocked, and the system has been unable to regen. At this point, take your car for a good high speed thrashing and it should get warm enough to regen and save the day. If not, they the dealers can “force” a regen event with their diagnoistic tools, although sometimes, if this is too late, them the DPF might need to be replaced (at vast expense). It’s also worth noting that in the event you arrive at your destination and by chance the DPF is in the middle of a regen event, things like cooling fans will stay running to try to keep some air moving through the engine bay. Early systems could end in a ‘thermal event’ when the car was stopped in the middle of a regen cycle…….

    alpin
    Member

    so i’m still looking at cars.

    have narrowed it down to Mondeo, Avensis or maybe an Accord. one thing that i keep reading is something about the DPF thingymajig that may blow at 100K. or it may not.

    what is it? and how much is it to replace?

    and does anyone have any tips when looking at either of the afore mentioned motors? have a few that i may look at this week, all around 4-6K€ and between 80K-110K miles on the clock.

    cheers!

    (if i were buying a bike i wouldn’t be having to ask all these questions…)

    Premier Icon tonyg2003
    Subscriber

    Hi the MK VII Honda accord cdti doesn’t have a DPF. I guess that these are the ones you are looking at for the mileage?

    joeegg
    Member

    A few months ago i bought a 2009 Mondeo 1.8 tdci to replace my mark 3.
    I chose the 1.8 because it has no dpf.I think the 1.8 was discontinued because it couldn’t meet emissions standards.

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