Going to be looking for a s/h car over the xmas period,read some horror stories about dpf filters clogging up in diesel cars.Don,t know much about engines ,so just looking for some advice,is there anyway of knowing if the dpf is clogged up or it has not had time to regenerate properly.Guess its a gamble on used cars.
dpf filters
- Thread starter bobby18
- Start date
It's a minefield alright. Avoid 'little old lady' diesel cars, the problems come when diesels with dpfs are used on short journeys and the system doesn't get hot enough to burn off the soot.
Avoid early iterations which didn't have the regen function. Look for something with reasonable mileage that was used for distance driving or less but linger journeys, if that makea sense. Maybe even try and find a non dpf diesel, a pre 2012 Hilux should be dpf free, pre 2011 definitely is.
Avoid early iterations which didn't have the regen function. Look for something with reasonable mileage that was used for distance driving or less but linger journeys, if that makea sense. Maybe even try and find a non dpf diesel, a pre 2012 Hilux should be dpf free, pre 2011 definitely is.
And when you buy one, use decent fuel. I avoid supermarkets. Wasn't sure whether it was an urban myth about their fuel quality but as I'm doing the same 70 miles round trip journey to work seven days a week till March I though it was a good opportunity to test it, so I've been using different fuels and logging the mileages.
In my Grand Vitara BP Premium and Esso Supreme offer the best performance and miles per gallon. I get around 25 more miles out of those brands than with supermarket fuel per tank and there is vastly less smoke when I put the hammer down. Tesco standard diesel is filthy. Clouds of black smoke. It definitely runs much cleaner on quality fuel.
If I have to use cheap fuel I'll add some DPF cleaner additive (paraffin - 2 stroke petrol mix works as well). I never seem to get soot build up now.
In my Grand Vitara BP Premium and Esso Supreme offer the best performance and miles per gallon. I get around 25 more miles out of those brands than with supermarket fuel per tank and there is vastly less smoke when I put the hammer down. Tesco standard diesel is filthy. Clouds of black smoke. It definitely runs much cleaner on quality fuel.
If I have to use cheap fuel I'll add some DPF cleaner additive (paraffin - 2 stroke petrol mix works as well). I never seem to get soot build up now.
Bear in mind also that the new stricter MOT regulations which came in this year apply to cars seven years old or newer. One puff of smoke from a diesel and it's failed. If I was buying a car without heavy mileage in mind and planning to keep it for a few years, I'd buy one older than seven years that's exempt from the new rules.
nun_hunter
Well-Known Member
I generally pootle around in my pick up truck and since getting the EGR blanked off and had the warning light remapped out I never have any black smoke even under hard acceleration and j know I'm not going to get issues with it being clogged at a later date. Something to consider with any diesel.
caorach
Well-Known Member
I had a 2009 Nissan X-Trail and had heard some horror stories about owners having awful trouble with dpf filters. However, as has been said, I think it is down to how the car is used. My X-Trail did considerable periods of 1st gear "off road" and forestry track type driving (probably 20 - 30 miles per week) plus it often sat ticking over for a while. However, most of my actual road journeys were relatively long and often with periods of motorway or dual carriageway driving and I'm assuming this allowed plenty opportunity for the gunk in the filter to burn itself off as I never once saw the dpf light come on in 7 years. Clearly my single example doesn't mean much but the general view supports the position that even if the car does a reasonable amount of ticking along in 1st gear type work as long as it gets regular longer runs then you will have no problem. I'd guess a lot of vehicles used for stalking mostly do longer runs to and from the stalking ground but one that is only used in town to run to the shops or even, perhaps, an estate vehicle that is rarely on the main road and mostly in 1st gear might be the problem areas.
Kevgun
Well-Known Member
I'm a Mechanic in my daytime job, if it were me i would pick a Car according to it's use, if you are doing short trips all time then Petrol would be my choice, 1 it's cheaper 2 there's not much, if any difference in mpg, otherwise a Regen is dependent on the condition of your Dpf but on average regen about every 300 -500 miles, most of the modern systems have an indicator light which tells you a regen is required, so a good 30 min drive with the revs kept above 2000 rpm will clear it out if the system is working correctly.
Petrol cars have become more efficient and most will match a diesel for mpg, but your limited if you want a 4x4
Petrol cars have become more efficient and most will match a diesel for mpg, but your limited if you want a 4x4
I have driven approx 300k miles in two 2 DTI Zafiras and have a record of all the fuel used. All fuel purchased from either Morrisons or Sainsbury and absolutely no issue, the myth re supermarket fuel is just that and it all has to meet industry standards. On the extremely rare occasions I have filled up with so called premium diesel there has been no difference in MPG or performance.
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243varmint
Well-Known Member
Incorrect I’m afraid.
They still have a DPF.
So they use low pressure and high pressure EGR valves. These are used mainly in and around town. Add blue is mainly used at higher speeds. So the combination of all three reduces emissions.
It all still has to go through the DPF.
The DPF has to get up to a certain temp to carry out its regeneration. So if it’s not being driving many miles or doesn’t get the opportunity to do a regen they get blocked up.
Then a forced regen can be done In lay mans terms you are forcing the DPF to have an old fashioned ‘chimney fire’ which burns all the soot out of the DPF. It reads the exhaust pressure before and after the DPF. Calculates the difference, then knows when a regen is required.
Not many miles per year. Get a petrol.
More mileage per year. Get a diesel.
Hope this helps a little.
Strange! When I took mine back for its first service, I asked about the dpf and was told: "You don't have one if you have AddBlue."
Italian tune up we call it ,good 3rd gear blast to clean the system out and use redex diesel once a month and every 6 a bottle of dpf cleaner through keeps my kia happy .As stated supermarket diesel is minging because the goverment insist bio diesel is added at 5 to 10% which is why theres a lotta smoke .So their MOT rule change is a joke as they have made you use carp through your motor
I put nearly four litres of unleaded in mine by mistake a couple of weeks ago before I noticed. Topped it up with 50 litres of diesel and drove it anyway. It went like stink and ran as clean as a whistle. Don't think I'll make a habit of it though...
Not a lot of lubricity in petrol. Shouldn't think too much of that would do the injectors or the valve seats much good.
Not a lot of lubricity in petrol. Shouldn't think too much of that would do the injectors or the valve seats much good.
Hi Finch.
What Engine have you mate?
My Mercedes Injectors would not have survived that. They are notoriously sensitive to fuel quality.
Coddy
Well-Known Member
DPF need to get to about 400 degrees to burn the soot out.
To get to this, it needs to be doing a decent run at about 2000-2500 rpm for 10 mins, especially if it has not gone into the regen cycle for a while.
If you have an auto, put it into Sport, or put it into manual. Take it onto a dueler or motorway.
As said in posts above, if you run about town all the time, then avoid a diesel with a DPF.
Forced regen is not great on the car, high revs, high temperatures, with the uderside of the car near the DPF getting hot enough to melt tar.
But if a diesel with a DPF is doing out of town driving regularly, there should be no issue.
To get to this, it needs to be doing a decent run at about 2000-2500 rpm for 10 mins, especially if it has not gone into the regen cycle for a while.
If you have an auto, put it into Sport, or put it into manual. Take it onto a dueler or motorway.
As said in posts above, if you run about town all the time, then avoid a diesel with a DPF.
Forced regen is not great on the car, high revs, high temperatures, with the uderside of the car near the DPF getting hot enough to melt tar.
But if a diesel with a DPF is doing out of town driving regularly, there should be no issue.
shakey jake
Well-Known Member
sorry to hi jac but has any one got proof that supermarket fuel is worse? it must meet a standard and i cant beleive tesco has its own fuel refinery? people comparing normal fuel to premium i get but surely all normal deisel is just deisel?
back on track id steer clear of all deisel engines, long term i think we will get screwed with tax
shakey
back on track id steer clear of all deisel engines, long term i think we will get screwed with tax
shakey
It’s not “worse”
It’s just the minimum standard of production is what o would call it .
Likes of shell add their own additives etc to it apparently
It’s all the same stuff from same refinery just add their own recipe of these additives to make it better.
Lot of boy racers used to use it as cheaper when the Subaru Imprezas first came out ..... and the engine management light would come on.
mechanics used to say just run some vmax or non supermarket fuel in and light would go off.
How true above is I don’t know but was explained to me by few mechanics like that.
I did my own tests and on my old shogun 2.8td in the winter back n forth to work I did notice that the shell vmax diesel did make things just that wee bit smoother less rattly and seemed more power marginally, just overall smoother “better”
Was it perceived ? Like a placebo maybe ... I dunnoe if it’s true or marketing hype .
Paul
It’s just the minimum standard of production is what o would call it .
Likes of shell add their own additives etc to it apparently
It’s all the same stuff from same refinery just add their own recipe of these additives to make it better.
Lot of boy racers used to use it as cheaper when the Subaru Imprezas first came out ..... and the engine management light would come on.
mechanics used to say just run some vmax or non supermarket fuel in and light would go off.
How true above is I don’t know but was explained to me by few mechanics like that.
I did my own tests and on my old shogun 2.8td in the winter back n forth to work I did notice that the shell vmax diesel did make things just that wee bit smoother less rattly and seemed more power marginally, just overall smoother “better”
Was it perceived ? Like a placebo maybe ... I dunnoe if it’s true or marketing hype .
Paul
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