Got my DPF cleaned out

[Sensibleboy]

shoehorn said:

Brick acid cleans the casing pipework too,threads,stud,flanges all come up nice and clean.
The only drawback is the fumes while doing the re-gen,whoa!

It also strips off any metal plating applied as a surface treatment on those parts. It's a great recipe for corrosion and it will happen very quickly too.

[MG CHRIS]

sherbertdip said:

MG CHRIS said:

Just wait till euro 5 with noX boxes and the like in the exhaust system come in. You think £1500 for a new dpf will be expensive try double the price for an entire exhaust system.

Eh? can you or somebody else explain what an x box is in the exhaust, why they won't be allowed and why it will cost £3k for an exhaust?

nox boxes its to reduce the level of nox emissions from diesel engine. nox is really harmfull to health specially in cities. The number of sensors and the layout means if it blocks up and with the failure rate for dpf I expect it to be the same then it will be a lot of money to replace when/if it needs it 3k is what ive heard from various courses on future technology of cars.

[john banks]

Does driving a diesel very hard help the DPF? When I drive my 3.0TDI at average 70mph cruise (so indicated 80 most of the time) I get 43mpg, when I use full pedal on a back road and get 19mpg average, I find it hard to believe I'm not making considerably more soot, it is just whether the EGT is sufficient to avoid clogging the DPF. However, when driven like this I get the same economy with the same journey time from my petrol which has an extra 320BHP but without trying to drive it hard.

Edited by john banks on Saturday 9th August 21:27

[MG CHRIS]

john banks said:

Does driving a diesel very hard help the DPF? When I drive my 3.0TDI at average 70mph cruise (so indicated 80 most of the time) I get 43mpg, when I use full pedal on a back road and get 19mpg average, I find it hard to believe I'm not making considerably more soot, it is just whether the EGT is sufficient to avoid clogging the DPF. However, when driven like this I get the same economy with the same journey time from my petrol which has an extra 230BHP but without trying to drive it hard.

No what kills them is very short stop start jounreys where the dpf/ engine etc never gets up to temperature this is in most cases. Wrong type of car for the purpose. But as anything nothing is ever that straight forward and as this thread proves people do have problems with them while doing the correct journeys etc.

[john banks]

Will I be actively helping it by driving it hard though? Journey is 15 miles of fast uncongested roads twice a day and between 0 and 15 miles late morning, so shouldn't be a problem anyway, yet people do have problems.

[MG CHRIS]

john banks said:

Will I be actively helping it by driving it hard though? Journey is 15 miles of fast uncongested roads twice a day and between 0 and 15 miles late morning, so shouldn't be a problem anyway, yet people do have problems.

Wont do any harm driving it harder will stop it clogging up just keep driving it as you are.

[shoehorn]

herewego said:

If you blanked off the EGR valve you'd be increasing the NOx emissions wouldn't you?

Only by the small amount the egr system dealt with if its working and clean,which bearing in mind how clogged and restricted the majority of egr valves,pipes and ports are,not a lot.

It still wont matter any way as the dpf is a filter in the exhaust to catch physical particles,not gases,its dumb.
The various temp and press sensors connected to it are for its own benefit,to tell the ecu of its condition/state/saturation.
Asides from restrictive faults like blockage or collapse which then trigger re-gen,restricted power or limp mode,it has no affect on what happens to the fuel/air before it gets to it.
Much in the same way your intestines have any say in what goes in your mouth or how much.

[shoehorn]

Sensibleboy said:

It also strips off any metal plating applied as a surface treatment on those parts. It's a great recipe for corrosion and it will happen very quickly too.

My truck dpf,which I partly see every time I walk past the thing has no more corrosion on it five or so years after cleaning it in brick acid than it had from the five years of use before it
Neither have I had any complaints from friends and customers concerning any of the others I have done or from others I know have that have used this method.

Also,besides the fact that the inside of diesel exhausts gets rapidly covered in a sooty,oily coat of crap and don`t generally rust like petrol exhausts the chances of a dpf outliving its casing are very,very remote.

[Megaflow]

shoehorn said:

Only by the small amount the egr system dealt with if its working and clean,which bearing in mind how clogged and restricted the majority of egr valves,pipes and ports are,not a lot.

It still wont matter any way as the dpf is a filter in the exhaust to catch physical particles,not gases,its dumb.
The various temp and press sensors connected to it are for its own benefit,to tell the ecu of its condition/state/saturation.
Asides from restrictive faults like blockage or collapse which then trigger re-gen,restricted power or limp mode,it has no affect on what happens to the fuel/air before it gets to it.
Much in the same way your intestines have any say in what goes in your mouth or how much.

The DPF will do nothing to the NOx. EGR systems reduce combustion temperatures so stop nitrogen oxidising. Particulate filters remove the particulate created by a locally rich mixutre during combustion.

[Mr Whippy]

MG CHRIS said:

sherbertdip said:

MG CHRIS said:

Just wait till euro 5 with noX boxes and the like in the exhaust system come in. You think £1500 for a new dpf will be expensive try double the price for an entire exhaust system.

Eh? can you or somebody else explain what an x box is in the exhaust, why they won't be allowed and why it will cost £3k for an exhaust?

nox boxes its to reduce the level of nox emissions from diesel engine. nox is really harmfull to health specially in cities. The number of sensors and the layout means if it blocks up and with the failure rate for dpf I expect it to be the same then it will be a lot of money to replace when/if it needs it 3k is what ive heard from various courses on future technology of cars.

Aren't Nox reduced by running non-lean on diesels, ie, using EGR to richen the mixture, thus necessitating a catalytic converter to clean up the nasties produced nearer an ideal AFR operation cycle?


Any way, NA petrols for me still. Nothing really goes wrong as long as it's not French

[MG CHRIS]

Mr Whippy said:

MG CHRIS said:

sherbertdip said:

MG CHRIS said:

Just wait till euro 5 with noX boxes and the like in the exhaust system come in. You think £1500 for a new dpf will be expensive try double the price for an entire exhaust system.

Eh? can you or somebody else explain what an x box is in the exhaust, why they won't be allowed and why it will cost £3k for an exhaust?

nox boxes its to reduce the level of nox emissions from diesel engine. nox is really harmfull to health specially in cities. The number of sensors and the layout means if it blocks up and with the failure rate for dpf I expect it to be the same then it will be a lot of money to replace when/if it needs it 3k is what ive heard from various courses on future technology of cars.

Aren't Nox reduced by running non-lean on diesels, ie, using EGR to richen the mixture, thus necessitating a catalytic converter to clean up the nasties produced nearer an ideal AFR operation cycle?


Any way, NA petrols for me still. Nothing really goes wrong as long as it's not French

It does to an extent but what it doesn't catch are the really nasty stuff the small particules which are free to excape to the air, this ie noticeable in cities like London, this is the main reason for euro 5 and stuff like Nox boxes that will come in.

But as you said n/a petrol for me to or a 90s jap turbo petrol of course.

[herewego]

BlueMR2 said:

herewego said:

Mr Whippy said:

But they're not driven how they are meant to be.

In any case I'm struggling to see if there is a net environmental gain by having DPF.

If the gain is marginal overall, not better to spend that cash on things that then have a better overall environmental impact?

Dave

According to the AA they give an 80% reduction in particle emissions. This seems quite significant.

80% reduction, till it spews that 80% back out in a few miles, diesels are going to get expensive to run soon if you need to go into a populated area anywhere. They are going to become the new motoring cash cow as they should be.

The discharge from the self cleaning process is completely different to the pm emissions caught by the DPF. Surely you can't imagine they put these things on for no reason?

[mjh64]

MG CHRIS said:

Just wait till euro 5 with noX boxes and the like in the exhaust system come in. You think £1500 for a new dpf will be expensive try double the price for an entire exhaust system. Its mental and I for one will not be being so blind to the fact and keep with my 90s mx5 fk all to go wrong, simple engineering and something you can actually work on.

EU5 has been with us since 2011 / 2012 EU6 will be implemented from 2015

[shoehorn]

Megaflow said:

The DPF will do nothing to the NOx. EGR systems reduce combustion temperatures so stop nitrogen oxidising. Particulate filters remove the particulate created by a locally rich mixutre during combustion.

Sorry old chap, didn`t read or comprehend the other posters question properly,my 3yo had woken up and decided to watch the storm from our covered decking and was making some noise doing so,I cant do 2 things at once it seems
It was made more as a comment on how poor egr systems are in light of how blocked they become over time and how little effect they could have on anything.
But my post clearly says that the egr has nothing to do with the dpf,which was main point for the post.

[Megaflow]

Indeed. EGR is a very powerful NOx reduction technology when it is new and working, but it rapidly gets sooted up and you have to question how much of them work as intended.

I do wonder if EGR will soon disappear completely though, to be replaced by SCR. EGR systems cost a lot of money, and are notoriously unreliable. If you then have to add SCR at a later date to clean the NOx further, there is a strong case to delete the EGR and dose more SCR.

[MG CHRIS]

mjh64 said:

MG CHRIS said:

Just wait till euro 6 with noX boxes and the like in the exhaust system come in. You think £1500 for a new dpf will be expensive try double the price for an entire exhaust system. Its mental and I for one will not be being so blind to the fact and keep with my 90s mx5 fk all to go wrong, simple engineering and something you can actually work on.

EU5 has been with us since 2011 / 2012 EU6 will be implemented from 2015

Noted yep euro 6 not 5.

[Mr Whippy]

Megaflow said:

Indeed. EGR is a very powerful NOx reduction technology when it is new and working, but it rapidly gets sooted up and you have to question how much of them work as intended.

I do wonder if EGR will soon disappear completely though, to be replaced by SCR. EGR systems cost a lot of money, and are notoriously unreliable. If you then have to add SCR at a later date to clean the NOx further, there is a strong case to delete the EGR and dose more SCR.

But since the worst case NOx condition is steady state driving (oxygen rich situations), you're gonna be dosing a LOT... you'd need to be re-filling it quite often I'd assume?!


I know it'd make a diesel less efficient due to pumping losses, but it'd be better to throttle it with an efficient system. Ie, Valvetronic on the BMW engines is a novel way of getting fine fill control with a bit more control on efficiency.

A block in the intake, or a block in the exhaust... which is worse


Treatment of gasses after the bad things have happened already, or richening mixes by pumping dirty gasses back through an engine seem a bit crude given the problem at hand is one of just limiting the initial intake quantity of air.

I remember reading about a Saab engine, maybe, that had a leaning head/cylinder casing so the compression and intake volume could be changed... or something along those lines.

Being able to just vary the engine geometry fundamentally would make a lot more sense, rather than these 'stick on' fix solutions.

Dave

[delboy735]

Megaflow said:

Indeed. EGR is a very powerful NOx reduction technology when it is new and working, but it rapidly gets sooted up and you have to question how much of them work as intended.

I do wonder if EGR will soon disappear completely though, to be replaced by SCR. EGR systems cost a lot of money, and are notoriously unreliable. If you then have to add SCR at a later date to clean the NOx further, there is a strong case to delete the EGR and dose more SCR.

Oh for gawds sake.....what's SCR please ??
Yes, I know I'm stupid, but I haven't a clue what you're talking about .....

[Megaflow]

Mr Whippy said:

But since the worst case NOx condition is steady state driving (oxygen rich situations), you're gonna be dosing a LOT... you'd need to be re-filling it quite often I'd assume?!


I know it'd make a diesel less efficient due to pumping losses, but it'd be better to throttle it with an efficient system. Ie, Valvetronic on the BMW engines is a novel way of getting fine fill control with a bit more control on efficiency.

A block in the intake, or a block in the exhaust... which is worse


Treatment of gasses after the bad things have happened already, or richening mixes by pumping dirty gasses back through an engine seem a bit crude given the problem at hand is one of just limiting the initial intake quantity of air.

I remember reading about a Saab engine, maybe, that had a leaning head/cylinder casing so the compression and intake volume could be changed... or something along those lines.

Being able to just vary the engine geometry fundamentally would make a lot more sense, rather than these 'stick on' fix solutions.

Dave

Agreed. Neither is great, but I don't think anybody is yet prepared to accept the cost and risk of variable compression yet.

delboy735 said:

Oh for gawds sake.....what's SCR please ??
Yes, I know I'm stupid, but I haven't a clue what you're talking about .....

SCR = Selective Catalytic Reduction. Roughly translate to ps injection.

Do you remember that thing on Top Gear many years ago, it was still the new Top Gear, where they were talking about injecting sheep urine into an exhaust stream to clean it up? Well its that, it became a production reality on trucks ~5/6 years ago, off highway ~1 year ago and will make it into cars at some point.

How does it work? Well it use's a reductant, urea or ammonia, to convert NOx in the exhaust stream into nitrogen and water by mixing the exhaust with the reductant and passing it over a catalytic substrate with a suitable coating applied to it to trigger chemical the reaction.

Edited by Megaflow on Tuesday 12th August 08:00

Edited by Megaflow on Tuesday 12th August 08:05

[AlanHoppo]

delboy735 said:

I'm going to sound really stupid now.....and not for the first time, how do you know if your car actually has DPF. I know mine has an EGR valve, that is becoming blocked up again, but don't know about a DPF. How do I find out ?

What vehicle is it? 🤓