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Now looking at a diesel and some Cat Ss.
For a low mileage driver (3Kpa but frequent 40-60mph trips of ~1hr) is the DPF a worry?
And Category S: even if you know the fully story and repairs etc it must be tricky to know the value accurately, so best only bought if the car is to be kept a long time?
For a low mileage driver (3Kpa but frequent 40-60mph trips of ~1hr) is the DPF a worry?
Depending on what type/generation of DPF and car, probably not. Some of the very early ones might be very expensively close to EoL, but will just need replacing. There are many many other things i'd worry about on a car that's done limited yearly mileage before i got worried about DPFs.
There are many many other things i’d worry about on a car that’s done limited yearly mileage before i got worried about DPFs.
Such as it being a cat S without proof of repair process .,..
Seen people buy catS only to find they look good but have been repaired on the cheap and there are either safety systems missing or damaged - electrical gremlins as a result or that the damn thing just rattles and squeaks as the dash hasnt been refitted correctly.
For a low mileage driver (3Kpa but frequent 40-60mph trips of ~1hr) is the DPF a worry?
No.
DPFs work as long as they can regenerate themselves (figure I saw was every 300 miles or so). This requires a trip of 20 mins or so of continuous driving. If you ONLY ever do short trips i.e. to the shops and back, a few miles, it won't get the chance to do it. Many cars tell you this with a warning message. If you ignore that warning message, then yeah it'll get blocked up.
If you do 1hr trips from time to time then it'll do the regen, you'll never know, and all will be well.
My recent purchase, a 2017 Renault Trafic 1.6 tdi has just put on its Antipollution light….the DPF, Adblue systems are all fine, no codes, but they think it’s one of a bunch of sensors or control units. Whatever happens it’ll be £££…
Modern diesels are a nightmare; the systems to reduce emissions are a disaster. My local service centre stated they’re getting huge numbers coming through with similar faults.
Future purchase will be petrol only….
Modern diesels are a nightmare
Meh. You have a choice, you either buy a high tech engine with good fuel economy and driving characteristics but more to go wrong, or you buy a low tech one with neither - it's the same for petrol or diesel. There's a small chance you will end up paying more out than you save in fuel.
Of course, there are still lots of sensors even in plain petrol engines. It's not really a diesel-specific thing any more.
has just put on its Antipollution light….the DPF, Adblue systems are all fine, no codes
That said, I'm not sure about that one. The light comes on to alert you to the fact there are error codes stored. So if there aren't any codes why's the light on?
For a low mileage driver (3Kpa but frequent 40-60mph trips of ~1hr)
For this usage case I wouldn't be considering a diesel unless it was free.
For this usage case I wouldn’t be considering a diesel unless it was free.
I dunno, petrol cars seem to be even pricier currently, everyone's got DPF anxiety it seems, but if your journeys are typically longer distances/higher speeds then a Clogged DPF isn't necessarily the problem to worry about, even if you're not driving it every day.
The original question really comes down to how handy you are with car spannering (half of which seems to involve a laptop now).
Used prices are bonkers currently and I do find myself casually browsing utter shit boxes with disgusting asking prices also. TBH if I didn't have family transport to consider I'd be all over the local 13 plate and older Corsas and Fiestas etc.
"Old", common small cars just make better sense to me generally if you're looking at a limited use case.
I know more about DPF’s than I’d like to having just shelled out £900 for a new one.
There are three modes of regeneration,
Passive - exhaust temp >350ish, pretty hard to achieve in normal driving unless you hold it in 4th on motorway or long hills under load.
Active - ecu adjusts airflows etc to force a burn of the accumated soot. Triggers once the soot level gets above a defined %. Needs 20 mins of steady driving to complete.
Forced - can be triggered in the workshop with the right kit if the active regenerations haven’t completed or cleared enough.
Then you have the ash level, which is what’s left behind after the regen/burn cycles. When this fills up, replacement is the only legit option. (You can have them coded out apparently..). Mine had done 160k without causing problems so not the end of the world.
I think that passive regen is when it adjusts injection timing to increase exhaust gas temps for a period. I don't tink you need active regen if you are driving motorway trips etc.
That’s an active regen when the soot level gets above a certain %.
At least on a Subaru anyway.
So if there aren’t any codes why’s the light on?
Several technicians are struggling to answer that question.... unfortunately it's got 200 miles before it won't start, regardless of what is really wrong (I suspect a NOx sensor). Clearly, I'm going to get Adblue coded out like many others once I've cleared the fault (can't code it out with the fault light on) which makes a mockery of the systems....
Bloke I used to share a workshop yard with used to buy and fix CatS by wrapping a massive chain round the yard gatepost and the damaged bodywork and accelerate off till he hit the end of the chain and pulled the body straight(ish)......
That’s an active regen when the soot level gets above a certain %.
I have read that there are catalysts in the DPF that heat up when hydrocarbons are present, so they put extra fuel into the exhaust stream to do this which heats them up hot enough to burn the soot. This is done either by injecting a bit of fuel into the exhaust stroke (VAG I think) or by means of a 5th injector in the exhaust manifold. This is the next level if the adjusting of the injection timing hasn't worked. That would mean two types of regen, in addition to just driving fast enough in normal conditions.
But things may have moved on since I read that.
Clearly, I’m going to get Adblue coded out like many others once I’ve cleared the fault (can’t code it out with the fault light on) which makes a mockery of the systems….
You don't want future problems so you are going to mess about with it? And produce more nasty emissions in the process? That sounds like a pretty bad idea to me.
A regen is a regen, it's just the way it's carried out that varies.
Very few vehicles will ever get a DPF hot enough to carryout any kind of soot reduction, without a regen being active.
And if you think you can achieve a regen at high engine revs, it just won't happen. To carryout a regen the injectors inject fuel during the exhaust stroke, which then hits the oxidising cat and results in raising the exhaust gas temperature to 5-650 degC.
If you rev the engine too fast (usually around 2500rpm is the cut off point), the ecu can't control the injectors accurately enough, and under high load exhaust oxygen levels are reduced, so regens get briefly paused.
Nearly all diesels are optimised to regen around 1500-2500rpm.
Personally I'd advise getting an OE DPF cleaned, rather than replacing it with an aftermarket part. Aftermarket parts might 'work', but they'll never last as long as OE parts, as they generally skimp on the actual guts of the cat/DPF.
The other option is a chemical treatment, but the ones that actually work, aren't usually available to the public.
@mikertroid there is a known issue with exhaust aftertreatment ECUs on those and the countdown not resetting. I think it's fixable via a software update now, but I'd have to check the TSB that covers it, however I'm not likely to be back at work for a while.
@mikertroid there is a known issue with exhaust aftertreatment ECUs on those and the countdown not resetting. I think it’s fixable via a software update now, but I’d have to check the TSB that covers it, however I’m not likely to be back at work for a while.
That makes more sense. Have you been to the main dealer?
Several technicians are struggling to answer that question…. unfortunately it’s got 200 miles before it won’t start,
Have you filled the adblue up? Normally x miles till no restart means it thinks it is empty
Thanks all, usual spectrum of responses 🤣 especially the extreme @doomaniac - anything to back yours up?
Having an enjoyable time on autotrader etc trying to find the ideal cynic-mobile, Leon ES and Twingo are the current top 2.
Re test driving a used car to see what it's like (the model, not nec that specific car) would folk normally I go to a nearby dealer and pretend they are buying?
Having run a VW 2.0tdi with a Dpf without any issues at all, over 200kms, Id be more worried about the Cat S details personally.
@doomaniac – anything to back yours up
well there’s 25 pence /l difference between them and modern petrols do nearly as many mpg as diesels ……. And LEZ are less of a concern.
I went from a life of diesels to a petrol 108.
Bit more road noise being a dinky toy with minimal sound insulation but so far enjoying it and it’s ultra low cost to buy/run/insure/free tax Worst so far is folk in big cars trying to bully it /cut it up but you can see it coming a mile off the perps are not very smart about it - it’s a lot like driving a camper van.
Yes all filled up adblue.... never got below 40%....if its not the NOx sensor, I'll go to the main stealers for software update as all components are working perfectly.
Just for the OP: I'd avoid Adblue as it's a common failure....to have a countdown at which point the vehicle is undriveable due to no fault, is ridiculous. Can't wait to delete! DPF fine if driven correctly.
to have a countdown at which point the vehicle is undriveable due to no fault, is ridiculous
Not really. You shouldn't be allowed to drive around spewing toxic gasses everywhere, should you? When there's an alternative?
Interesting, I just realised I've never paid attention to my dpf. Every tank or so it does the needful (I can tell because the engine can get a bit lumpy) and it's just sailed through the MOT.
I have just discovered (I think) that it has an Eolys system, something that needs to be added every 36k and fills the dpf by about 75k (1.6hdi engine).
I've had it for 130k miles and topped up nothing.
Anyone have any idea whilst a Google a shed load more to get an answer.
Do you get it serviced at the dealer.
A correctly working system being used as designed likely doesn't need topping up between service till later in life when things start to degrade.
No, I service it. From 81k miles to it's current 210k over 6 years.
Found a line that says "dry dpf regeneration on 116bhp models", trying to find more.
What age is it. Not all 1.6hdi had additive systems.
Came in in those in December 2015. - certainly in the 1.6hdis fitted to Peugeot partners/Berlingos
2011.
There is a blanket statement from Volvo saying all Volvo 1.6 have the eloysis thing, but it's 2010 (and strictly speaking it's a PSA engine).
Phew, it's a dry system that doesn't need an additive (there is a heater around the dpf to get the temp).
Very confusing.
The additive isn't to burn soot out of the DPF by the way, It's there to reduce the amount of NOx in the exhaust. I think that as a consequence of this you need less EGR and you can presumably run the engine hotter which should improve efficiency and yes, reliability.
Eolys is a chemical that leads to the creation of softer soot, so it burns of more easily in the DPF.
You can top it up before it runs out, but it needs to go on a computer to have the level reset anyway, so you're as well leaving it until it generates a fault. When it does need topped up, and if you're doing it yourself, spend the extra on the hose and fittings, as it makes the job far easier and a lot less messy.
It doesn't affect NOx production, as NOx production is a result of hot combustion temperatures (in excess of 650degC IIRC).
EGR was the primary way of reducing combustion temperature by reducing the oxygen level so you got a cooler and slower burn that avoided the generation of NOx. The downside was slightly increased soot production due to the lower temperature, but actually increased fuel economy under certain conditions.
Selective Catalyst Reduction (aka what AdBlu supports) allows combustion temperatures to run higher, as the SCR treats NOx, which allows for reduced EGR use so the DPF doesn't have to work as hard, which is pretty much essential for later particulate size restrictions.
Ah, I didn't realise Eolys was a different additive. So some cars have both right?
Not that I'm aware off, but I've not really been looking.
I've certainly not noticed any Eolys tanks on anything with an SCR system, but that's not to say they aren't there.
Eolys was a PSA thing (hence why it's also found on PSA powered Fords/Volvos). It dopes the main fuel tank every time you add fuel.
You shouldn’t be allowed to drive around spewing toxic gasses everywhere, should you? When there’s an alternative?
😎
A few people have said things like this:
DPFs work as long as they can regenerate themselves (figure I saw was every 300 miles or so). This requires a trip of 20 mins or so of continuous driving. If you ONLY ever do short trips i.e. to the shops and back, a few miles, it won’t get the chance to do it.
And AIUI, it's not true.
I gave it a bit of thought on my last car as it was a diesel and a few other owners had hooked up various lpatops/dataloggers to the ECU to monitor such things and found things like:
1) You could tell when it was about to happen / happening as the car would switch all the electronic accessories on to maximize engine load (headed screen, mirrors, AC etc). One guy even wired an LED into the heated mirror circuit so it was easy to tell if the system was regenerating so as to not shut the engine down mid cycle.
2) The ECU gave a percentage complete status during the regeneration. Once upto temperature it actually went down quicker at traffic lights than it did at a constant speed. So it seemed like getting the engine hot enough (i.e. don't be a lazy arse driving trips you really should be walking/cycling) was the key factor, not the actual nature of those trips.
Clearly, I’m going to get Adblue coded out like many others once I’ve cleared the fault (can’t code it out with the fault light on) which makes a mockery of the systems….
The "I'm alright Jack, **** everyone else" approach.
The “I’m alright Jack, **** everyone else” approach.
🤣
Not at all....I don't drive in urban areas which is what the Adblue is all about. It's all fine. Just need to get it fixed first before getting it deleted 😖
If you develop such fragile systems, people will always work around them.
I don’t drive in urban areas which is what the Adblue is all about.
Not really. It can easily be an issue in a village with some traffic lights. Don't do it. It's not worth it. You probably just need a software update.
I gave it a bit of thought on my last car
Wasn't that fairly old? Things move on.
So it seemed like getting the engine hot enough (i.e. don’t be a lazy arse driving trips you really should be walking/cycling) was the key factor, not the actual nature of those trips.
AIUI it needs to be hot enough and be on for long enough to cover the regen itself. In my car it doesn't tell you that it's regenning, and if you turn it off it will simply try again later. The problem occurs when you continually interrupt it, because it keeps trying and this can end up diluting the engine oil presumably due to injecting fuel into the exhaust stroke.
I just did a 2hr motorway journey with my Bluetooth odbd scanner hooked up.
When I started soot % was at 55%. It would go up if DPf temp was <300, fall slowly if DPf temp >350.
When it got to 65%, the active regen switch activated, and the DPf temps rose to about 650 deg. Soot % fell rapidly to 0%. Maybe 5-10mins to complete, active regen switch stayed on for another ten minutes. Next hour of driving at 70mph left the soot % at ~8%.
On the trafic there's a pipe on the exhaust manifold that goes to a sensor that gets blocked at the manifold end. Hard to get at. Main dealer quoted £475 to replace pipe. Local garage unblocked it for £65. Seems to be a common problem and doesent leave any codes
Fascinating, jam-bo. I've only ever had my DPF soot loading read once at a diagnostic session at a garage, and it was 12%, but I had no idea it went up and down that quickly.
What conditions made the DPF temperature go above 350?
Long hills pretty much. But then you probably accumulate more than you lose on the downhill. I could log it I guess but I’m not that motivated.
Bluetooth OBDB reader was £12 well spent.
Holy thread tangent Batman!
@trail_rat good point - I was thinking diesel as it is a good bit quicker, but that will cost over time Vs purchase price of a petrol.
I would hate a NA petrol as it wouldn't be nice to drive, but that is purely a personal preference. A direct injection turbo petrol is likely to have a similar level of engineering complexity as a diesel.
Holy thread tangent Batman!
given the thread title, it seems remarkably on topic…
I would hate a NA petrol as it wouldn’t be nice to drive,
The word would....suggests your theorising again.
It's not 1992 anymore tech has moved on. I was as surprised as anyone.
Still shit at towing though.
I would hate a NA petrol as it wouldn’t be nice to drive, but that is purely a personal preference.
We bought a 2.0l non turbo petrol pretty much on the basis that it would be simple, less stressed & less to go wrong - Mazda 3 & get 60mpg on a long run.
OP - if you are still after a 100bhp 1 tonne motor, have you looked at Mazda 2 1.5 diesel sport?
I would hate a NA petrol as it wouldn’t be nice to drive
our 2.4NA petrol V70 is lovely wafting down through France but admittedly we don't tow with it. It's a 5cylinder and ticks over as smooth and quietly as the day we bought it even though it now has 200k on it. The rest of the time it does short journeys and it's never had DPF/turbo/injector/DMF issues as it doesn't have any!
I would hate a NA petrol as it wouldn’t be nice to drive
I'm a big fan of forced induction but that's just nonsense. Some of the best cars I've ever driven (sound/handling/performance) have been NA and petrol - 4, 6 and 8 cylinder.
With regards to the DPF question you don't need to be doing motorway journeys but you do need to be ticking certain criteria and fairly frequently driving for long enough for the car to get up to temp and run a regen if required. For my current car (335d) you also need over 1/4 tank of diesel and no outstanding fault codes relating to the DPF for it to regen. You can usually feel when it's doing it, mine seems to prefer steady driving on A roads rather than set speed/rpm on the motorway.
Cat S wouldn't bother me depending on what the damage was and the damage and repair was well documented.
And the fuel economy?
I'm sure it does have injectors, btw, and it may well have a DMF as well.
I’m a big fan of forced induction but that’s just nonsense. Some of the best cars I’ve ever driven (sound/handling/performance) have been NA and petrol – 4, 6 and 8 cylinder.
Ok what I meant was - any sensible sized NA petrol with fuel economy I'd be prepared to accept.
Ok what I meant was – any sensible sized NA petrol with fuel economy I’d be prepared to accept.
Yeah, that makes sense - that and the tax bracket it'd no doubt be in!
that Mazda looks bang on, cheers!
Only wish I'd found out about it before buying my Volvo V40 diesel ☹️
Actually browsing some of the local used dealerships there seems to be some lowering of prices but mostly it's the dirty diesel that seems to be coming down faster, reckon there's been a spate of trade-ins...
Example: There's an 08 plate Galaxy nearby on 180k, they want £1600, decent MOT till October. I mean OK it's 14 years, old but that's a lot of car that you could cram people and/or bikes in to belt up and down motorways at the weekends. A year ago they would have been asking at least £4.5k for that I reckon.
At the same time dinky petrol cars seem to be steeper locally, and autos (missus only drives automatic) still carry a substantial markup.
I think we're going to stick for a wee bit longer, see if those 1L automatic runabouts come down as that's what we really need, but I am tempted to go look at that Galaxy this weekend if it's not already sold.
I'd keep well clear of the diesel Mazda engine unless most of your millage is out of town. Dpf regen happens on a timer and diesel is sprayed down the exhaust if not up to temperature. The residue drains back into the oil sump. I changed my oil three times last year as the level was too high (about an extra 2.5 litres!). I never got much better than 42 mpg on my Mazda 6 even on a run. It was bloody fast mind.