Diesel Particle Filters?

[Big Tav]

Hi guys, I went to two different dealers yesterday and both tried to put my wife and I off diesel cars. They said if it is just being used as a family car and not doing 20,000+ miles a year the DPF filters will cause us problems and be expensive to fix. Is this true and something I should be worried about or is it the sales guys just trying to move the petrol motors instead?

I am buying a car for the Mrs and we will keep in for 5-6 years.

Cheers.

[frosted]

Only about 1000 threads bashing the diesel dpf cars on here , I wouldnt ask for impartial advice here . My feeling is that you should go for the petrol if you do less than 15k a year, if you are dead set on TDi then go for a non DPF car

[eltax91]

Which marques? Taxi driver i was with this morning (lots of miles, but mainly town work) was bemoaning the DPF problems in his Mazda6, which is a Ford TDCi lump I believe?

[cptsideways]

Yes it is true, DPF's are failing on runabout cars on a very regular basis, many of the manufacturers are advising against them for low mileage/town driving users.

Unless your doing some heavy footed mileage on a weekly basis avoid them.

Was it a Mazda or Ford dealer by any chance? if so the sales guys have had training on the subject & to be honest it is good advice.

[anonymous-user]

If you only drive short distances in town, so a) the car never warms up, and b) you never get any serious load or revs onto the engine, then yes, a DFP can clog (as it never gets enough heat to "regenerate". However if this is your typical driving style you shouldn't be driving a diesel anyway!!

If you just make sure you occasionally "give it some beans" all will be fine!

[Otto]

Max Torque is on the money above.... DPF's filter out and collect the soot. They actually convert the soot to harmless gas through a chemical reaction that needs heat, and usually for a decent amount of time (i.e. 40 mins). So, to effectively clear themselves out, you really need to be running for an hour or so (i.e. get it up to temperature, then maintain that temperature). Idle does not usually generate enough heat for this reaction to take place, so motorway driving is your best bet.

Some vehicles are putting things in place so that they can regen at idle (by injecting extra diesel very late, to create heat in the exhaust).

[frosted]

Otto said:

Max Torque is on the money above.... DPF's filter out and collect the soot. They actually convert the soot to harmless gas through a chemical reaction that needs heat, and usually for a decent amount of time (i.e. 40 mins). So, to effectively clear themselves out, you really need to be running for an hour or so (i.e. get it up to temperature, then maintain that temperature). Idle does not usually generate enough heat for this reaction to take place, so motorway driving is your best bet.

Some vehicles are putting things in place so that they can regen at idle (by injecting extra diesel very late, to create heat in the exhaust).

In my manual it says to drive at 40-60 mph in 4th-5th gear at 2200 rpm or higher for 5-10minutes

[Big Tav]

It was a Mazda & Vauxhall dealer actually. I guess the DPF is not under warranty? So on a late mode car (still under warranty) that will drive 30 mins in to Edinburgh a few times a week a diesel is best avoided then? We will own the car for a few years. Do Insignia's and Mazda 6 have this problem?

[shouldbworking]

I am surprised the dealers were honest!

http://www.theaa.com/motoring_advice/fuels-and-env...

[Muzzer]

OP - Why are you and your OH looking at diesels?

Is your mileage quite high or....?

DPF is a problem - I have a friend who does a 25 mile commute every day and has had nothing but problems with his.

I deliberately ordered mine without one.

But if you don't do a lot of miles why not just buy a petrol anyway?

[frosted]

Muzzer said:

OP - Why are you and your OH looking at diesels?

Is your mileage quite high or....?

DPF is a problem - I have a friend who does a 25 mile commute every day and has had nothing but problems with his.

I deliberately ordered mine without one.

But if you don't do a lot of miles why not just buy a petrol anyway?

Can you elaborate please , Im really curious about what the constant problems could be , and of course what car is it ?

[Munter]

I don't have DPF problems. But the car generally runs for 2 hours+ at motorway speeds. So that fits the pattern of useage being discussed.

Petrol for short time/low mileage journeys.
Diesel for killing the planet on a budget.

[anonymous-user]

Otto said:

Max Torque is on the money

Nasty habbit of mine, soz....;-)


All diesels fitted with DPF's have an active regeneration mode, where, as mentioned, injection quantity and timming are varied to increase exhaust massflow and temperature (at the expense of added fuel consumption). This is used to "light-off" the DPF, which when the exhaust stream returns to the usual operating point of "excess air" then oxidises the soot trapped in the DPF matrix at high temperature. This takes a maximum of approx 5 mins at a typical cruising load. The problem is that with a very heavily loaded DPF, a zero vehicle speed regeneration cannot be triggered, as the heat release without any cooling airflow can be enough to actually melt the DPF canister and cause a "thermal incident" (otherwise known as "oh F**k, my cars on fire....;-)

To guarentee a decent regen, you need to accelerate hard through the gears with a warm engine, this is get the DPF to the light-off temp, then back off and cruise at a decent engine rpm but a cruising load to allow it to complete the burn.

[Petrolhead_Rich]

frosted said:

if you are dead set on TDi then go for a non DPF car

Muzzer said:

I deliberately ordered mine without one.

I thought all 2002ish onwards DERV's had these hateful, expensive, power sucking, thief baiting lumps of st now???

Even with a good run every day (200miles per day average) the £600 lump needs changing every 72,000, with short journeys I have heard of them failing in as little as 8k, so really your looking at a £1000 service every 18 months!

Buy a petrol, you won't notice the difference with the fuel, but the clogged injectors, knackered turbo's, DPF filters, high pressure fuel pumps etc etc will cost alot!

[Big Tav]

You know how it is when the OH wants one! She likes the way they drive.

Also how bad of a problem is the DPF? What happens and how expensive is it? Could I just take her car once a week for an hour drive and it would be sweet?

[TooLateForAName]

Otto said:

Some vehicles are putting things in place so that they can regen at idle (by injecting extra diesel very late, to create heat in the exhaust).

And some of those are reported to suffer engine failure. Diesel getting into the sump and causing overfilling oil problems.

[Big Tav]

Petrolhead_Rich said:

frosted said:

if you are dead set on TDi then go for a non DPF car

Muzzer said:

I deliberately ordered mine without one.

I thought all 2002ish onwards DERV's had these hateful, expensive, power sucking, thief baiting lumps of st now???

Even with a good run every day (200miles per day average) the £600 lump needs changing every 72,000, with short journeys I have heard of them failing in as little as 8k, so really your looking at a £1000 service every 18 months!

Buy a petrol, you won't notice the difference with the fuel, but the clogged injectors, knackered turbo's, DPF filters, high pressure fuel pumps etc etc will cost alot!

REALLY????!!!!

Bill like that would definitely offset the higher purchase price and the lower road tax wouldn't it!

Edited by Big Tav on Monday 13th December 15:04

[eltax91]

Big Tav said:

You know how it is when the OH wants one! She likes the way they drive.

I know what you mean. Last time SWMBO had a car, to replace her 1.8 MX5, I took her to see:-

Focus 1.6 Petrol
Alfa 147 Petrol
A3 1.8 NA and 1.8 T Petrol
Leon 1.6 Petrol
Corolla 1.6 Petrol

Nothing... nada, hated them all. We drove a 52 plate A3 TDi and she was smitten. I think it felt familiar (to my Skoda) and she says it "feels faster, and is harder to stall"

Thankfully it's not a DPF car, but I will have to have serious words when time comes to change, as I suspect allDiesels within scope will be DPF.

As an aside, anyone know if PSA's HDi (2.0) of recent (60 plate) vintage has a DPF?

[dmitsi]

Big Tav said:

REALLY????!!!!

Bill like that would definitely offset the higher purchase price and the lower road tax wouldn't it!

Work on the new generation DPF's will show much improvment, but for now there's still a large risk if the engine doesn't get pushed enough.
New diesels have lots of expensive components designed to meet the stringent emission regs of different countries. Therefore failures costs lots more.
If it's only for short journeys and you don't want to fork out silly money; get a petrol.

Edited by dmitsi on Monday 13th December 15:24

[y2blade]

go for a Euro 3 Diesel then