Diesel Do

So having had the emmissions-test cheat mode removed from my car, I was interested to see on BBC Watchdog (everyone’s favourite combination of fuckwits and whingers) that there seems to be a growing number of complaints following the “service action”.

It seems the complaints centre around limp-home mode getting triggered, and it seems that the EGR valve has been a common failure. It does seem that logically, the EGR may be more active post-fix in order to reduce NOx at the expense of more particulates and reduced power/economy.

The Watchdog article fairly obviously prompted this letter from VW:

Page one of the VW “all is well” letter. Click to embiggen.


Page two of the VW “all is well” letter. Click to embiggen. Note in section 3, bullet point 5.

And there’s something interesting in section 3, bullet point 5 that gives VW a potential get-out. On page 1, they’re saying that they’ll be favourable to clains for 2 years/up to 160K miles, but then say that they won’t cover a DFP full of ash. There’s scant infornmation about what the VW fix does apart from removing the rolling road detection, but consensus seems to be that is alters injection quantity, pattern, and timing, and tweaks EGR. All of these could have an effect on the particulates produced.

Now, since Euro V, we’re not allowed to pump those particulates out to atmosphere (boo hiss!):

So the particulates have to go somewhere, and that somewhere is the DPF. DPFs obviously can get full of soot, and they then need to be regenerated. This can happen passively (if it gets hot enough), or can be triggered by the engine ECU injecting fuel on an exhaust stroke, so that it burns in the DPF. This turns the soot to ash- the ash that VW won’t replace your DPF for if it’s full of it. Which is interesting: you can’t get something for nothing, and the reduced NOx emissions comes (apparently) at a cost of more particulates, which means more DPF regens, and therefore more ash, so a shorter DPF life.

I don’t know what to make of this, to be honest. My own VW seems have economy and performance unchanged, and doesn’t seem to be doing active regenerations often, but you don’t miraculously lose the NOx without paying for it somewhere. I suppose EGR and DPF life remains to be seen. I’d really like to see a full analysis/reverse engineering of the remapped ECU (because, on the 2L engine, that’s all that happens).

This is interesting in the light of news recently that the sale of conventional diesel & petrol cars is to be outlawed by 2040. I think that’s a bit of a non-story: we’re already in the twilight of internal combustion cars: both petrol and diesel cars are now loaded with lots of controls and mechanisms not to increase efficiency or power, but to limit harmful emissions, and even with those they pollute our environment in a way that is impossible to contain. Electric cars will still pollute, of course, (and will still congest the roads), but the internal combustion engine is on it’s way out, inevitably. We’ll still have IC cars on the road by 2040 (and assuming I make it, I’ll be a pensioner), but they’ll be diminishing in quantity.

2 Responses to “Diesel Do”

  1. species5618 Says:

    i woudl like to know more about the enviromental impact of mining rare earth metals which make up some of the new battery tech,
    How does the global impact of mining all the rare toxic stuff compare to fosel fuels

    So we have 23 year to perfect fuel cells, or other fuel > electrical enegry process

    or may be hydrogen directly into a suck sqaush bang blow machine

  2. stymaster Says:

    There’s the mining of the metals (much of which, I believe, is in Chinese hands), and of course a lot of charging infrastructure to work out, unless the tech you mention can be sorted.

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