Diesel particulate filters DPF....

[watchnut]

Hi all, can someone please explain to me why i can't get a decent answer out of salesmen about these things

I currently have a 1.3 turbo diesel corsa which is getting tired and I am thinking of changing it (124500 miles)

I understand that many diesels now come with these things in them, and that if they don't run hot for a while they build up, clogg up, and cost money to put right

I will be using the car...Fiesta diesel or Polo 1.2 diesel, or maybe a Mini 1 diesel to teach Learners in. i have not made up my mind yet which car to go for to replace my Corsa 06 plate (old shape)

One salesbloke said that it would glog up if not run for at least 20 mins at 2000_3000 revs so it could burn it all up and clean the thing every day.

I will be using the car just about every day doing anything from a few miles to maybe 150 miles in a day, most of it around the slow stop start streets of Southampton, with occasional runs down the A31 and back for D/C training, and find that I don't worry about miles per gallon only hours per gallon with use of fuel as some lessons might only do a couple or three miles if we are doing reversing, where as on average an hours lesson would be around 20-25 miles..........but, the engine is almost constantly running and I assume running hot, so will it clean the filter to stop problems?

cheers

[TheEnd]

You'd have close to the perfect storm with regards to DPFs, they'd need a regen maybe once a week of a continuous run at 3000-ish RPM on a motorway, town driving and no long journeys is the worst conditions for them.

[mph999]

From my understanding, DPF csrs are not suitable for round town driving.
Have on on mine, not an issue as I do long enough journys at high enough speeds to keep it clear - needs (apparently) 20 mins at 40 - 50 mph to clear, though this will differ between makes.

£1000 odd pounds if it blocks up ... not worth the risk.

Plenty of stories of people having issues when they only use the car as a run around, as mentioned, it takes a sustained 'high' speed run to clear.

I don't believe they all clear every day - mine only clears when it needs to, as it injects more fuel to reach a higher temp I can spot this as the fuel economy drops , it's not daily (at least for me). Other makes (mines Volvo) ay well differ.

I certainly would not recommend getting one on a car that has the use yours will.

M

Edited by mph999 on Tuesday 24th September 19:06

[GroundEffect]

An idling diesel engine has exhaust gas temps of about 5-600C. That isn't enough for a regen of the DPF.

Basically a DPF cleans out by burning the particulates. This can be done in a number of ways such as overfueling in the cylinder (which is very bad for particulates) or by using a vapourisor, which literally sticks fuel in to the exhaust before the DPF. This raises the temperature of the DPF brick and burns off the particulates.

It won't do either of those unless the brick temp is high enough for the regen to work - this is where you need high rev/high load running of the engine. Exhaust gas temps of a diesel are around 850-900C under full load and about 750-800C after the turbo. These are the numbers necessary.

[N7GTX]

GroundEffect said:

An idling diesel engine has exhaust gas temps of about 5-600C. That isn't enough for a regen of the DPF.

Basically a DPF cleans out by burning the particulates. This can be done in a number of ways such as overfueling in the cylinder (which is very bad for particulates) or by using a vapourisor, which literally sticks fuel in to the exhaust before the DPF. This raises the temperature of the DPF brick and burns off the particulates.

It won't do either of those unless the brick temp is high enough for the regen to work - this is where you need high rev/high load running of the engine. Exhaust gas temps of a diesel are around 850-900C under full load and about 750-800C after the turbo. These are the numbers necessary.

Are you sure about these numbers? When I do forced regens using IDS, the temp is always shown on the menu screen along with the degree of particulate remaining.

Before starting a forced regen IDS warns you that temps may go as high as 600C and you should not park over grass etc, only concrete due to prolonged temps in this region. When idling the temp rapidly drops to around 160C and only reaches the desired temp when coolant temp is above 60C and prolonged regenerating forces the temp up to around 550C. At this point the particulate % is seen to start dropping and continues until the back pressure falls within limits.

So for IDS and Bosch KTS the required regenerating temp is 500-600C.

[TheEnd]

Your Fords might have Adblue, which means you can do the regens at a lower temp.

[Faxo]

If I remember correctly, Renault and Nissan have a new 1.5 diesel that has almost eliminated DPF issues. Honest John from The Daily Telegraph raves about it

Basically, a DPF needs a good run every week to carry out a regeneration. I think all new Diesel engines have one due to emissions

On the other hand, have you considered a petrol, possibly an Ecoboost Ford? Obv no DPF issues, high almost diesel like MPG and cheaper at the pumps?

[Megaflow]

TheEnd said:

Your Fords might have Adblue, which means you can do the regens at a lower temp.

As blue for SCR, which is nothing to do with the DPF.

[watchnut]

thanks for the replies so far,

As my car will not just be doing stop start , but an occasional run up and down D/C's the filter should clean it's self ......I take it then that the build up is a problem when the engine is doing very short journeys not getting up to temp.....like wifey doing a 10-15 commute to and from work?

A Vauxhall dealer told me the dpf would be an issue on the new corsa's

A mini dealer said to me today that in 6 years of dpf's in mini's he has not known a problem

A ford monkey didn't know nufthink

The suggestion of a Fiesta 1.0l eco thingy has also been on my think list, as it is supposed to do near on the 52-54 mpg I am currently getting out of my corsa, so with petrol being about 5-6p a litre cheaper, may be, on top of the car being cheaper to buy over a diesel the way to go.....wot do you lot think?

[chrisw666]

You'll struggle to get 50s from an Ecoboost fiesta unless its steady longish distance work, my OH has a 1.2 zetec one and its returning around 40mpg on her commute (this goes up if I use the car) but it was over £2k cheaper than a lesser specced diesel.

[Monty Python]

Megaflow said:

As blue for SCR, which is nothing to do with the DPF.

Probably thinking of EOLYS, which reduces regeneration temperature to ~350°C from >600°C.

[Poison Tom 96]

The Fiesta is good to learn in (Currently learning in an AA one) Certainly has enough go about it.

HTH

[TheEnd]

Monty Python said:

Megaflow said:

As blue for SCR, which is nothing to do with the DPF.

Probably thinking of EOLYS, which reduces regeneration temperature to ~350°C from >600°C.

Yea, I was sure there was some sort of fuel additive to make regens happen at a cooler temp.

[addz86]

They're a pain in the arse. You can get them removed and the car remapped to suit which would be a good idea if just pootling round town, motorway driving at a constant RPM re-gens them

[scorcher]

The Skoda dealer where my missus buys her cars for teaching in warned her away from the diesel Fabia because of DPF issues. She bought a 1.2 petrol Fabia which in her opinion drives better than the diesel and is more forgiving when pulling away and doing low speed stuff. Financially she's a little bit worse off but she hasn't had any issues with the petrol model, whereas her last Fabia Diesel 1.6CR was nothing but problems where it kept getting stalled, so its probably evened out anyway.

[GroundEffect]

N7GTX said:

GroundEffect said:

An idling diesel engine has exhaust gas temps of about 5-600C. That isn't enough for a regen of the DPF.

Basically a DPF cleans out by burning the particulates. This can be done in a number of ways such as overfueling in the cylinder (which is very bad for particulates) or by using a vapourisor, which literally sticks fuel in to the exhaust before the DPF. This raises the temperature of the DPF brick and burns off the particulates.

It won't do either of those unless the brick temp is high enough for the regen to work - this is where you need high rev/high load running of the engine. Exhaust gas temps of a diesel are around 850-900C under full load and about 750-800C after the turbo. These are the numbers necessary.

Are you sure about these numbers? When I do forced regens using IDS, the temp is always shown on the menu screen along with the degree of particulate remaining.

Before starting a forced regen IDS warns you that temps may go as high as 600C and you should not park over grass etc, only concrete due to prolonged temps in this region. When idling the temp rapidly drops to around 160C and only reaches the desired temp when coolant temp is above 60C and prolonged regenerating forces the temp up to around 550C. At this point the particulate % is seen to start dropping and continues until the back pressure falls within limits.

So for IDS and Bosch KTS the required regenerating temp is 500-600C.

What temps are those calling out? I'm only going on what I've actually seen measured in a vehicle.

[daydotz]

the JTDm-2 in the alfa's maybe worth research

[Pwig]

daydotz said:

the JTDm-2 in the alfa's maybe worth research

I was just about to post this.

They re-gen on idle.

They have attached the DPF to the Manifold so it's pretty much always warm.

Simple when you think about it.

[R12HCO]

Just do you normal thing and when not instructing, take it for some abuse down a dual carriage way loading it up in 4th and 5th.