Do Diesel particulate filters really work?

sevenhills

These filters are just that, a filter. So any soot going into it will just clog up the filter, eventually.
That does not happen, because when doing motorway driving, they reach a certain temperature and preform a regeneration, meaning the heat up and expel all the soot. So all the soot that was stored, is pumped back out again, making the DPF pointless.

I have a petrol car myself, but I believe a DPF does not have any wires going to it, to heat it up.
Have I got something wrong here?
Some of the exhaust gases are recirculated, so modern cars are alot better at burning the soot, so that part must be true, and the Adblue system must help too.
DPFs have been used in cars since 1985, maybe the new ones are really good?

worried_jim

It's not pumped out. Extra fuel is used to burn the particles, this is what the regen cycle is.

societys_child

A little knowledge . . .;)

Paradigm

worried_jim wrote: »

It's not pumped out. Extra fuel is used to burn the particles, this is what the regen cycle is.

Surely that results in smaller "ash" particles (still containing all the nasties) that can equally be breathed in & may in fact reach further into the lungs?


Another point, if DPFs are meant to improve the environment who thought it a good idea to inject loads more diesel to clear them thus creating more pollution?

chrisw

Can't win really:-

CO2 emissions rocket as car buyers ditch diesel

https://uk.yahoo.com/news/co2-emissions-rocket-car-buyers-112000354.html

forgotmyname

What car used a DPF in 1985? Seems someone reads wikipedia and doesnt check the facts.

Seen the soot chucked out the back of a car doing a regen? If it needed a forced regen then its likely to be fairly sooty at first.

Paradigm

forgotmyname wrote: »

What car used a DPF in 1985? Seems someone reads wikipedia and doesnt check the facts.

Seen the soot chucked out the back of a car doing a regen? If it needed a forced regen then its likely to be fairly sooty at first.

Not sure what you mean?

sevenhills

forgotmyname wrote: »

What car used a DPF in 1985? Seems someone reads wikipedia and doesnt check the facts.

Seen the soot chucked out the back of a car doing a regen? If it needed a forced regen then its likely to be fairly sooty at first.

1985/95/05 what ever the year, they have had a long time to develop.


How is a regen forced, does the DPF heat up in some way?

Mr.Generous

sevenhills wrote: »

1985/95/05 what ever the year, they have had a long time to develop.


How is a regen forced, does the DPF heat up in some way?

Fuel is either injected into the exhaust system via an injector and fuel line, or on some cars injected into the cylinder during the exhaust stroke of the pistons so unburnt fuel gets to the right place and ignites incinerating at very high temperature the particles.

However they do smoke good and proper on a forced regen. Generally achieved by revving to 3000rpm in neutral when the DPF is full, or software driven via the onboard diagnostic port. Smoke and waste of fuel doing it makes me wonder if it is beneficial myself too.

sevenhills

Mr.Generous wrote: »

However they do smoke good and proper on a forced regen. Generally achieved by revving to 3000rpm in neutral when the DPF is full, or software driven via the onboard diagnostic port. Smoke and waste of fuel doing it makes me wonder if it is beneficial myself too.

Halfords do a regen, £85, if the soot burns, it sounds like anyone with an open fire could sort it out

Ectophile

A forced regen is a bit of a last resort to stop the DPF clogging up totally. The alternative is an expensive new DPF.


It shouldn't be necessary if the car is driven on long journeys from time to time.


In normal use, the "burning" in the DPF should produce a lot less soot than it has previously trapped. So overall, it's an improvement.