Do you have a milage figure for problems arising?

I live in London close to a school and see a couple of mums in 185 bhp XC90's every school day. I've asked them if they've ever had any error messages about the DPF and they've both said no. They don't do long runs at weekends that often but they do sometimes they say.

Any old excuse to speak to a school-run mum.......

I may be wrong but don't these XC90 use a separate tank to inject a liquid (?) into the DPF?

Beemer

No , not on the large volvos , they have a different type of particle filter which doesnt need changing or Eloys fluid ..

Volvo do not use an extra reagent injected into the exhaust stream. The liquid you refer to contains an expendable catalyst which is injected into the exhaust stream and catalyzes reduction of nitrogen oxides to nitrogen. Other reagents added in the exhaust may promote oxidation of the soot in DPF at a lower temperature. I think BMW and Mercedes use such reagents for reduction of NOx. Evidently BMW do not use an added reagent to oxidise the soot in the DPF, but have a fixed catalyst in the DPF (See http://www.bmw.com/com/en/insights/t...le_filter.html).

The Volvo system is to raise the temperature of the DPF by injecting extra fuel in the exhaust stroke to raise the temperature of the DPF and oxidise the soot without any catalyst. The exhaust stream of a diesel has plenty of oxygen gas left over from what was taken into the cylinders. Some manufacters of heavy diesels use this system, but they have a separate injector that injects the fuel directly into the exhaust stream. Volvo and VW use the normal injectors and program them so that during the regeneration cycle they inject fuel into the cylinders in the exhaust stroke so that this extra fuel is swept into the exhaust stream. It oxidises in either the catalytic converter or in the DPF and raises the temperature in the DPF.

Perhaps I might, and that would be about 300 miles.

Last week I drove to a far away town, to tend to a gravely ill relative. Since then I have driven about 300 miles, hopping to the hospital and back, with no single journey over 10 miles.

Yesterday, I got a failure display that turned out to be the Electronic Throttle Body. Yes, diesels have throttles these days, and one of their purposes appears to be participation in DPF regenerations.

See my post #39 in the following thread...
http://volvoforums.org.uk/showthread.php?t=121184

Assuming there may be many other DPF-related components on these cars that are failing, I'm beginning to think that the scale of problems caused by DPF technoloogy may be FAR more widespread than we realise.

Hi Bill

Is that 300 miles because of a failure of the Electronic Throttle Body or with the car working properly and just down to the DPF not coping with the short journeys?

Roy

Checked the link and now I'm a bit confused. The Electronic Throttle Body is part of the EGR system and nothing to do with the DPF. Clan says they usually fail due to carbon build up.

Wiki says "a throttle in a turbocharged diesel engine to decrease the intake pressure, thereby initiating EGR flow." Clan says it only operates for a few seconds on the D5.

Just to add, every Volvo I've ever owned since 1984 has has some form of EGR.

Hi Roy,

So far as I understand (still learning, could be wrong), the throttle body in question is an air intake throttle, as normally expected on petrol cars. A wiki page suggests that it's been fitted to diesels since Euro IV engines onwards, and one it's purposes appears to be to reduce the air flow during regeneration, thereby reducing exhaust flow. I guess that allows the hot exhaust gasses to hang around for longer in the system, and thus heat up the DPF.

With hindsight, my car - having endured 300 miles of urban driving - was very likely trying - and maybe even suceeding - to regenerate during Sunday's drive in the country. But then I surprised it by making that detour down a 14mile country track, averaging 15mph, during which I'm speculating that the DPF regeneration systems, including that throttle valve would have been repeatedly activated, with 'over-use' contributing to it's untimely demise.

I have found an extremely detailed and seemingly authoritative description of DPF regeneration on a jaguar forum, as applied to their own cars, and which also includes the operation of the throttle valve. In the absence of such a detailed description from Volvo, the Jaguar one makes interesting reading...

http://www.jaguarforum.co.uk/viewtopic.php?f=22&t=25040

...That link might be interesting for anybody and everbody who wants to know the secrets of DPF regeneration, regardless of any interest in current diversions. The level of technical detail far surpasses anything I've seen on the web before. Just bear in mind that we don't know how closely it conforms to Volvo's systems though. Now, if only Volvo would publish something similar...

Hi Bill

I may be wrong but my understanding of the the electronic throttle in the EGR is to balance or cut off the EGR. Nothing to do with air intake. The D5 is still has the usual diesel injection system and that is nothing to do with the EGR. My D5 dosn't have a DPF but it does have the EGR. The electronic throttle is just a butterfly flap and an electric motor. More like bad luck and a bit too much carbon probably. I always use Shell V+ diesel in the hope it keeps the system a bit cleaner from carbon deposits.

Volvo's DPF appears to be a standalone unit. It has sensors mounted on it and a bit of code in the software that reacts to the readings it recieves and uses the injection system to charge the DPF with fuel, but all those parts it has anyway. Only the DPF itself is additonal.

The Government has been interfering with the biodiesel mix and my personal view is that is the cause of the overfueling issue was down to that, and Volvo's software update fixed that.

It's going to be interesting to see how the stop/start system being fitted to new cars is going to affect the DPF's

All the best.

Roy