DPF deletion, MOT's and the law?

[Akagi]

I read on a gov.uk page written in 2013 that MOT's now include a DPF check for vehicles which would have come with one as standard and that vehicles will fail if it has been removed.

First and foremost, is it true that it has been illegal for so long? Tuning companies have provided remap and DPF delete services for ages. Has this been stopped now?

Secondly, do the checks MOT testers carry out (if they do) actually include checking inside the DPF housing? If it is simply a visual check, could you just remove the internal filter itself?

I honestly didn't realise that the law had changed.

https://www.gov.uk/government/news/new-rules-for-mot-to-test-for-diesel-particulate-filter

 

[Akagi]

So moving forward, DPF deletion is a no-no then basically.

Are there alternatives to DPF deletion which are legal, such as replacing the DPF with a smaller and less restrictive one?

I think I read somewhere that someone with an Alfa 2.4 JTDM replaced his dual DPF's with a single smaller "racing" DPF?

 

[Akagi]

Racing DPF

That's not what I would call it. I put it in quotation marks for a reason!

Someone on Autotrader is selling their 2.4JTDM which is mapped to 260HP and he said it had a "racing" DPF.

Acme are you going to bolt a dpf somewhere in your polo engine bay, then remove it and see if the mot tester notices......?

Ha Not exactly. I may have to look into a diseasal if I get one of the jobs I have been interviewed for recently, and I really don't want one with a DPF.

I thought it would be quite obvious that I know my 13 year old Petrol Polo doesn't have a modern DIESEL particulate filter. I'm not a total spanner.

And I know the difference between a cat and a dpf. I know a lot more about cars than people give me credit for... The knowledge just gets tainted by some of the stupid things I say/do.

 

[Akagi]

Everyone seems to say "delete" when talking about removing something from a car. Enthusiasts, garages, tuning specialists etc. DPF Delete, Cat delete, centre silencer delete, MAF delete, EGR delete, delete delete DELETE.

 

[Akagi]

Yes but your forgetting that the majority of people now have a distorted view that diesels are also faster than petrol with all that torque bro

Well they are.

If you are towing a bus up a cliff face.

Also no Hypernuts. No.

That would mean my insurance is invalid right now because of my err...thing.

 

[Akagi]

Because I honestly believe that DPF's are absolutely stupid and pointless inventions and their existence irks me... They stop harmless soot from coming out of the back, then use diesel to burn/clean the soot out. Which... means it comes out the back anyway, just in a shorter space of time!!?!

The presence of a DPF is surely more harmful to the planet than not having one anyway.

Plus they are restrictive and reduce performance and economy.

 

[Akagi]

Who cares about the people, its all about that derv.

Watching an informative video about DPF's atm...

 

[Akagi]

Information on different types of DPF and re-gen systems.

I'm beginning to understand that now, watching this 30 minute DPF presentation.

It seems that some DPF regeneration systems use differential pressure sensors to detect the change in exhaust gas pressure before and after the DPF, to decide when the DPF is clogged enough to warrant a re-generation. This is fine, that makes complete sense. If the car is driven on long runs, it may never need to re-gen the DPF.

However some other systems re-gen the DPF based on fuel burned, mileage, or other factors, so they might initiate a DPF re-gen when it doesn't need doing at all.

When it comes to the actual re-gen process;

VW seem to have the right idea by putting the DPF pretty much immediately after the manifold, so that the exhaust gas is hot enough to burn the soot all the time, and they dont need a re-gen cycle.

Others systems inject diesel into the exhaust so that the heated gasses flow through the DPF and clear out the soot, and they do this on the exhaust stroke. Similarly some GM engines have an injector inside the exhaust system to puff diesel in just before the DPF. These sorts of system combined with the differential pressure sensor, would be in my eyes an almost perfect design. (second only to the simplicity of the VW design) Though the former which injects diesel on the exhaust stroke can apparently cause oil contamination (fuel getting into the oil). Is this sort of thing taken into account in the manufacturers oil change interval?

However some systems seem to just rev up the engine so that the whole exhaust heats up and the gas is hot enough to burn out the DPF? What rubbish! Is that true?

I don't want my car to sit there wasting diesel for 5 minutes, being all smelly and loud, because a manufacturer couldn't be bothered to implement an effective system.

Is there a resource somewhere which would tell me what manufacturers use what DPF re-gen systems?

 

[Akagi]

You have over simplified that just a little....

Revving the engine?

DPF regen requires relatively high speed cruising to provide adequate load and hence heat energy. I know of no system that does high speed idle for regen, the airflow running over the car is very usefuel when dealing with the external temps they get to.

For example its the high heat energy in the DPF thats leading to EGR systems that take exhaust after the DPF and then run through a larger low pressure EGR cooler before getting back into the intake manifold. Otherwise under regen its just too hot to use pre DPF.

Diesels are a nightmare. I will never buy one with my own money

I saw some re-gen videos where the car was stationary and holding the revs at about 4K for 5 minutes or so. One of a 1.6TDCI Focus, one of a Zafira 2.0 CDTI, one of a Brera 2.4JTDM. Were they "forced" regens then? And normally it would be done when the car is moving?

Blackhawk mentioned his TT doing the regen after he pulled onto his drive, so I assumed that would have been stationary too ?