Discussion
The law is quite clear on this. It's an MOT failure if any of the emissions equipment is removed (inc EGR valves), or not working. MOT testers have a responsibility to look for this when testing.
In reality, the DPF is hidden in the engine bay, and normally surrounded by plastic covers that are not allowed to be removed during the MOT test, so it is never spotted in my experience. It is however up to a 5k fine for driving a car with this removed.
In the real worls, removal of the DPF will add 15% horse power (ish) and reduce fuel consumption by 15%. However, since the engine needs to be mapped to remove the DPF, it's sometimes difficult to seperate out the DPF removal improvemnt, and the mapping improvement. Normal stage 1 power maps will increase BHP / torque by 30 odd % and DPF removal will improve fuel efficiency by 20% or so.
In reality, the DPF is hidden in the engine bay, and normally surrounded by plastic covers that are not allowed to be removed during the MOT test, so it is never spotted in my experience. It is however up to a 5k fine for driving a car with this removed.
In the real worls, removal of the DPF will add 15% horse power (ish) and reduce fuel consumption by 15%. However, since the engine needs to be mapped to remove the DPF, it's sometimes difficult to seperate out the DPF removal improvemnt, and the mapping improvement. Normal stage 1 power maps will increase BHP / torque by 30 odd % and DPF removal will improve fuel efficiency by 20% or so.
bearman68 said:
The law is quite clear on this. It's an MOT failure if any of the emissions equipment is removed (inc EGR valves), or not working. MOT testers have a responsibility to look for this when testing.
In reality, the DPF is hidden in the engine bay, and normally surrounded by plastic covers that are not allowed to be removed during the MOT test, so it is never spotted in my experience. It is however up to a 5k fine for driving a car with this removed.
In the real worls, removal of the DPF will add 15% horse power (ish) and reduce fuel consumption by 15%. However, since the engine needs to be mapped to remove the DPF, it's sometimes difficult to seperate out the DPF removal improvemnt, and the mapping improvement. Normal stage 1 power maps will increase BHP / torque by 30 odd % and DPF removal will improve fuel efficiency by 20% or so.
Good answer, why are so many offering this service then ?, I wasn`t really looking for it ,just researching possible DPF problems, symptoms etc & find all these establishments ready to remove them & remap In reality, the DPF is hidden in the engine bay, and normally surrounded by plastic covers that are not allowed to be removed during the MOT test, so it is never spotted in my experience. It is however up to a 5k fine for driving a car with this removed.
In the real worls, removal of the DPF will add 15% horse power (ish) and reduce fuel consumption by 15%. However, since the engine needs to be mapped to remove the DPF, it's sometimes difficult to seperate out the DPF removal improvemnt, and the mapping improvement. Normal stage 1 power maps will increase BHP / torque by 30 odd % and DPF removal will improve fuel efficiency by 20% or so.
They are often removed and mapped due to the complexity and cost of fitting a new one. Personally I have seen many issues with the early DPF filters on PD VW engines, where the combination of early software, and old fashioned engine design can cause real issues with the DPF. Add to this the wrong sort of mileage, the cost and complexity of replacement can make it seem like an attractive option.
The law has changed many times since they where introduced, I had a 2008 Leon FR TDI with the troublesome PD170 engine and I had my DPF and EFR removed. Back then there wasn't any mention of DPF removal on MOT but IIRC around 2010-2011 MOT rules got updated.
as said above these days its a failure.
as said above these days its a failure.
The quicker and better option is to simply not buy a car with a DPF if you are not doing the type of driving that it works well with.
Sadly far too many customers are d
heads and get seduced by inflated and frankly false claims of 600mpg. And pay more for a Diesel car at the initial purchase and then pay (generally) more for the fuel at the pumps as well. Then wonder why in 5K miles they've not broken even yet than if they'd bought a Petrol car 
Sadly far too many customers are d
heads and get seduced by inflated and frankly false claims of 600mpg. And pay more for a Diesel car at the initial purchase and then pay (generally) more for the fuel at the pumps as well. Then wonder why in 5K miles they've not broken even yet than if they'd bought a Petrol car the folk I know that have got a dpf delete is due to problems with the emissions systems that nobody could fix or were just going to keep flinging new parts at it in the hope it would fix it.
One friend spent close to a grand on new parts and it still wasn't running right. Car was off the road for several days at a time.
In each case, remap and dpf delete = no more problems - plus more power and more mpg.
One friend spent close to a grand on new parts and it still wasn't running right. Car was off the road for several days at a time.
In each case, remap and dpf delete = no more problems - plus more power and more mpg.
Drive Blind said:
the folk I know that have got a dpf delete is due to problems with the emissions systems that nobody could fix or were just going to keep flinging new parts at it in the hope it would fix it.
One friend spent close to a grand on new parts and it still wasn't running right. Car was off the road for several days at a time.
In each case, remap and dpf delete = no more problems - plus more power and more mpg.
What was the car? Cause in my experience there's not actually that much to go wrong with DPFs.One friend spent close to a grand on new parts and it still wasn't running right. Car was off the road for several days at a time.
In each case, remap and dpf delete = no more problems - plus more power and more mpg.
Fundamentally the dpf collects the soot from the engine
Overtime this builds up and blocks the dpf.
the dpf sensor is connected by tubes to before and after the dpf itself. It measures before abnd after pressure to determin how blocked it is.
Once a threshold is met it needs to be burnt off
Car does this by raising the exhaust temperature
It does this by chucking more fuel in/adjusting the timing
Car burns off the soot.
This is the point where it goes wrong for a lot of users. They car does this, but then because they don't do long journeys, it gets stuck half way through. And when it starts up again it's throwing more fuel in to try and raise temperature. But its never getting enugh time to finish the regen. Eventually the car goes into limp mode and the customer takes it to the dealer who force regen it. But it doesn't address the issue that the car is unsuitable for the owner. I knew of one owner who was back every month for regen but wouldn't ever entertain trading it in for an identical petrol car.
Pressure is make to tolerance
car goes back to normal running mode.
Now on an side issue the effect of burning the soot is you get ash left in the filter. Over time this ash will build up. And eventually it WILL mean the dpf needs replacing anyway. Something I daresay those with high mileage cars have not considered as a looming bill. Different manufacturers think different life spans. VW IIRC used to say 200 thousand KM (120 thousand miles)
IME
I've seen sensors go wrong
I've seen wiring issues give the ecu the wrong info
I've seen injectors fail which means the dpf gets filled with fuel and kills it Or even turbos leak oil into the dpf and kill it
I've seen dpfs lose their efficiency and need replacing
But for someone to be throwing money at "fixing it" and it not getting anywhere means you are either at the wrong repairer. Or it's simply not the car for them.
The DPF system on the newer Common Rail VAG engines is fine, the Pump Duse engines weren't designed to have a DPF, so when they decided to bolt them onto the PD170 and very late PD140's it was always going to spell trouble. Combined with the Siemens ECU and Injectors on the PD170 (The previous PD engines had a tried and tested Bosch system) it was a disaster.
Has 2 sets of new injectors on my PD170 and then removed the DPF & EGR.
Has 2 sets of new injectors on my PD170 and then removed the DPF & EGR.
AJB88 said:
The DPF system on the newer Common Rail VAG engines is fine, the Pump Duse engines weren't designed to have a DPF, so when they decided to bolt them onto the PD170 and very late PD140's it was always going to spell trouble. Combined with the Siemens ECU and Injectors on the PD170 (The previous PD engines had a tried and tested Bosch system) it was a disaster.
Has 2 sets of new injectors on my PD170 and then removed the DPF & EGR.
So that passes it`s mot ok I suppose.Has 2 sets of new injectors on my PD170 and then removed the DPF & EGR.
A DPF isn't required for a Euro 4 diesel - it will pass the Type Approval limits that applied at the time without, but manufacturers fitted them to trial the tech, or for those who were concerned enough about air quality to want to pay extra for one.
Any Euro 5 or 6 that left the factory with a DPF will require it to pass Type Approval, and it's an offence to alter the vehicle such that it doesn't meet the type approval standard that applied when it was new (yeah, I know - unlikely to ever be picked up)
There's been press coverage of the number of vehicles that've failed the MOT for a removed DPF, even with just the physical inspection, and it's a growing number.
With all the air quality problems in urban areas and the threat of court action from both the UK Supreme Court and Brussels it'd be a brave person who ignored the writing on the wall and went ahead and removed the DPF now. I expect a very large number of MOT failures when the emissions test changes in the future.
Any Euro 5 or 6 that left the factory with a DPF will require it to pass Type Approval, and it's an offence to alter the vehicle such that it doesn't meet the type approval standard that applied when it was new (yeah, I know - unlikely to ever be picked up)
There's been press coverage of the number of vehicles that've failed the MOT for a removed DPF, even with just the physical inspection, and it's a growing number.
With all the air quality problems in urban areas and the threat of court action from both the UK Supreme Court and Brussels it'd be a brave person who ignored the writing on the wall and went ahead and removed the DPF now. I expect a very large number of MOT failures when the emissions test changes in the future.
Adrian E said:
A DPF isn't required for a Euro 4 diesel - it will pass the Type Approval limits that applied at the time without, but manufacturers fitted them to trial the tech, or for those who were concerned enough about air quality to want to pay extra for one.
Any Euro 5 or 6 that left the factory with a DPF will require it to pass Type Approval, and it's an offence to alter the vehicle such that it doesn't meet the type approval standard that applied when it was new (yeah, I know - unlikely to ever be picked up)
There's been press coverage of the number of vehicles that've failed the MOT for a removed DPF, even with just the physical inspection, and it's a growing number.
With all the air quality problems in urban areas and the threat of court action from both the UK Supreme Court and Brussels it'd be a brave person who ignored the writing on the wall and went ahead and removed the DPF now. I expect a very large number of MOT failures when the emissions test changes in the future.
I've never seen any car fail an MOT due to DPF removal. (as in, no-one ever posted up a valid cert saying that).Any Euro 5 or 6 that left the factory with a DPF will require it to pass Type Approval, and it's an offence to alter the vehicle such that it doesn't meet the type approval standard that applied when it was new (yeah, I know - unlikely to ever be picked up)
There's been press coverage of the number of vehicles that've failed the MOT for a removed DPF, even with just the physical inspection, and it's a growing number.
With all the air quality problems in urban areas and the threat of court action from both the UK Supreme Court and Brussels it'd be a brave person who ignored the writing on the wall and went ahead and removed the DPF now. I expect a very large number of MOT failures when the emissions test changes in the future.
I've had no issues at all. There must be hundreds of thousands of cars running DPF deletes in the country. Cars will change hands and other owners may not be aware they are missing emissions control software. They will not make every single one replace with original emissions software. It simply won't happen.
Current and future MOT tests are only visual inspections of smoke.
Mine passed the smoke test with flying colours despite being heavily tuned with big turbo, fuel pump etc.
In the real world it only traps soot and a quality custom remap will be virtually smoke free anyway.
There is no downside really, if you are concerned about visual inspections you can have OEM downpipe removed, cut open, gutted and re-welded.
There are lots of companies who specialise in this. If you are in the south I can put you in touch with the guy who does all my tuning.
Rich_W said:
What was the car? Cause in my experience there's not actually that much to go wrong with DPFs.
But for someone to be throwing money at "fixing it" and it not getting anywhere means you are either at the wrong repairer. Or it's simply not the car for them.
An PD in a Passat and a CR in a T5.But for someone to be throwing money at "fixing it" and it not getting anywhere means you are either at the wrong repairer. Or it's simply not the car for them.
Both were doing the sorts of miles and journeys that should not cause DPF problems.
I agree that perhaps the garages involved didn't sound too clued up however once the remove and remap option was available to them it was a no brainer. A final solution.
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