DPF removal and MOT failure - going beyond a visual check?

colino

Have a search for how ridiculous the application of DPFs have really been for London Hacks. Expensive to bolt on to get round the law. drastically reduce mpg and to top it all, their regenerations create those smaller, more dangerous particles that the human lungs absorb more easily.
DPFs and DMFs, components created by committees of accountants and bandwagon-jumping politicians.


Don't worry about any sense coming to the MOT soon, the gears grind ever more slowly at the newly created and more confused DVSA. They could have went down the Californian Smog tests route, which cover both emissions and ecu interrogation, but even that has been corrupted and you can buy your way out of the test.


Complain to your MPs, we don't want to pay extra for bad engineering, if you want better air, get lean burn engines built and have them run on cleaner fuels.

nickcc

Peugeot owners can buy the Lexia diag system which allows them to force a re gen whenever is required, don't have a clue re London Taxis as I don't live there and don't own one.

welfayre

Shaolin_Monkey wrote: »

I've seen > 2000 rpm and 20 minutes stated in a manual. 3000 rpm is pretty high for a diesel engine and running at an hour like that would take some doing.

Each vehicle will have its own procedure. Corsas rev up to 7000 or 8000rpm so 3000rpm isn't even half the max. My experience is mainly with LCVs though so maybe trucks etc are different? I deal with a lot of Merc Sprinters and they need very long runs (or several shorter runs) to fully regenerate (e.g last one I did was out for 40mins and DPF went from 219% Soot content to 97%). The problem with the regeneration process is that even if the process completes a full cycle it doesn't mean the DPF has been completely regenerated. If one of the conditions (exhaust temp/coolant temp) drop below the programmed level it doesn't actually burn off the stored particles in the filter. Bit off topic lol

mattyprice4004

gilbert_and_sullivan wrote: »

I suspect any self respecting MOT tester would be able to tell from tapping the DPF canister whether it was empty or not, so if it echoes like an empty bucket expect it to fail.

Thats assuming the MOT tester gives a toss one way or another.

Would require some serious electronics to interrogate the system so i can't see that for some time.

Anyone who is really bothered could do as the hot hatch lads do with decats and slip a functioning DPF on for the test and remove once tested.

Meself, i can't be bothered with Diesels any more, far too complicated and troublesome.

That won't work, as a lot of DPFs are double skinned so the outer skin will sound hollow.

chrisw

welfayre wrote: »

Each vehicle will have its own procedure. Corsas rev up to 7000 or 8000rpm so 3000rpm isn't even half the max.

I don't think there are any diesel vehicles that rev that high, certainly not Corsas. I would imagine they would explode quite spectacularly at 8000rpm. Part of the diesel experience is having high power and torque at low revs rather than a screaming petrol engine. They can both be enjoyable in their own way.

gord115

welfayre wrote: »

Corsas rev up to 7000 or 8000rpm so 3000rpm isn't even half the max


Even petrol corsas don't rev to 8000rpm and certainly no diesel engine!

attila_

The whole idea of dpf is that it should regen when the car is on the move! That's why you hear people ripping up motorways in an attempt to fix dpf issues and why manuals state 2000rpm plus.

If regen happened in cities it was make the matter worse! We'd all be inhaling plumes of PM.

Retrogamer

As far as i'm aware Vosa have advised to check visually only.
I'd imagine anyone who tries to fail it on sounding hollow is on shaky ground.
Vosa tend to give people the benefit of the doubt. If they can't verify 100% it's missing then they won't fail it.
Same with third rear brake lights. If it's wired in and not working it's a fail. If it's not wired in it passes. As the wires are tucked away and you can't see them Vosa guidelines during MOTs are if you can't visibly see it's connected then it's a pass and advise.

atrixblue.-MFR-.

attila_ wrote: »

The whole idea of dpf is that it should regen when the car is on the move! That's why you hear people ripping up motorways in an attempt to fix dpf issues and why manuals state 2000rpm plus.

If regen happened in cities it was make the matter worse! We'd all be inhaling plumes of PM.

unfortunately a car is not intelligent enough to know when its in a city to not regen itself, it WILL regen where ever/when ever it wants to.


most new cars are now regenerating its DPF whenever its on the move.

mrmot

Plugging in and reading things won't be a problem, it's what OBD2 is designed for, one code reader should be able to access any emissions critical data over all vehicle manufacturers. The problem lies in what to check and what is it telling you?, that will rely on vehicle specific information being available to the tester.

This is forecast to come in, in 2018:

https://mattersoftesting.blog.gov.uk/how-the-eu-roadworthiness-package-affects-the-mot/

Interestingly it mentions tailpipe inspections, I'm hoping its got down to common sense in that a car with a working DPF won't have a sooty tailpipe, but it's probably DVSA speak for a more complicated measuring procedure.