DPF regen causes diesel to be not as cheap as you think shocker…

700quid for a coolant hose….. They nailed your hat on with that ….. Or did you miss it and cook the hg ?

Surely this is evidence the car needs a good blast / blow through on a regular basis 😉

My last Smart CDi didn’t have a DPF and averaged 67.2 mpg over 27195 miles.
My current Smart CDi has a DPF and has averaged 65.8 mpg over 28547 miles but the engine has 9 hp more than the last one.
Hardly a massive amount of difference either way.

The best thing is probably to drive quickly but constantly in a too low gear. Ragging it with hard acceleration might not get the exhaust temp up high for long enough, and when you floor it it might make more smoke and make matters worse.

This seems as good a place to ask as any; some Diesels look after their DPFs by injecting stuff. Off the top of my head I’m thinking Mercs and some Frenchies. Anyone have any experience of the reliability of DPFs in those??

It depends what stuff you’re on about.
PSA engines use EOLYS fluid, which is injected into the diesel tank everytime you refuel. It’s a mix of chemicals which helps to lower the required temperature to carry out a regen.
I say PSA, because fords with 1.4/16s use PSA engines, and also have the doping system.

I can’t say there’s much difference in reliability. DPF issues can be pretty much narrowed down to two main causes. Vehicle use isn’t suited to DPF regen i.e. lots of short journeys where things never get hot enough for regens, or a base engine fault, which means too much soot is being produced and the DPF is being loaded too quickly.

Newer Merc/VWs are now also using Adblue injection and catalyst systems (commercial vehicles have only had to start using DPFs since Euro6/late 2014, as they mostly relied on Adblue injection/catalysts to meet emission limits). Adblue is an additional catalyst system, which helps to further cut various gas emissions, but you still need the DPF to handle the particulates.
I’ve not had anything to do with the car systems yet, but certainly every truck manufacturer has had issues with their Adblue systems.

Certainly, given the amount of technology that is now required for a diesel to meet emission levels, the economies of them in cars is quickly diminishing. A couple thousand pound of extra tech on a new truck, with the occasional thousand pound bill is relatively little in the grand scheme of running costs, whereas on a car it is a major cost.

The best thing is probably to drive quickly but constantly in a too low gear. Ragging it with hard acceleration might not get the exhaust temp up high for long enough, and when you floor it it might make more smoke and make matters worse.

Regen processes do vary quite a bit, but a good drive keeping the engine under reasonable load and aim for maintaining above 2000rpm will generally keep the regen process happy.

Mc, VW have been using selective catalytic reduction on their US market diesels for a while. Apparently you don’t need EGR, and I’d read that there were fewer particulates produced.

The reason SCR could meet emission levels without EGR, is the SCR handles NOx emissions. The sole purpose of EGR is to reduce combustion temperature to reduce NOx creation at source, but the downside of that is you increase soot/particulates, which you then need a DPF to handle.

Most commercial vehicles opted for SCR due to fuel economy. At the time Euro 4/5 were reaching production, IIRC EGR systems resulted in a 8-10% hit in fuel economy, which when you’re dealing with vehicles doing single digit miles per gallon, is a major cost.
However a couple commercial manufacturers did use an EGR system combined with a conventional diesel catalyst, and sold it on the basis you didn’t have any adblue systems to deal with skipping over the fuel economy issues.

For cars/vans, the EGR fuel economy hit was a far cheaper option than adding a SCR system, and some vans avoided DPFs up until Euro5, as there was no legal requirement or tax benefit.
The reason alot of cars had DPFs was to meet the tighter tax levels, not because they needed it to meet the Euro emission levels.

Now Euro 6 is here, commerical vehicles need a mix of all systems, and car/van manufacturers are having to chose between expensive systems and fuel economy.