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DPF What is it?


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#41 F6HAD

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Posted 30 November 2010 - 02:00 PM

Andy, good stuff mate.

Yes, it's a shame we need to make such a long trip just to get some decent service... but it's always a pleasure dealing with the lads at HH so it's worth it.
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#42 Fizz

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Posted 30 November 2010 - 06:42 PM

How does the car feel now Andy did they give the latest and greatest DPF software update too!


They mentioned that it needed an update for the DPF but I don't think they have touched the remap part of the software as it feels the same as before the light came on.

#43 Fizz

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Posted 30 November 2010 - 06:44 PM

but it's always a pleasure dealing with the lads at HH so it's worth it.

They were top notch as always, They let me use one of the salesmen's desks to do some work while I waited and there was plenty of coffee on tap.

#44 Anthony

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Posted 15 January 2011 - 12:59 PM

Not sure if my input is going over what people already know, but below is my take on how DPFs work. I'll try not to run on.

To meet ever stringent emissions VMs (vehicle manufacturers) have after treatment systems to help. This means that engine out emissions are trapped and dealt with in the exhaust. The 2 main systems are DPF and SCR. Diesel Particulate Filters trap particulates on a filter bed, whilst Selective Catalytic Reduction uses a catalytic reaction (chemical type reaction) to convert NOx into less harmful gases (essentially into exhaust gases that aren't harmful and arn't legislated for). SCRs need an additional fluid to generate the reaction called urea, which is now sold in liquid form on petrol station forecourts as adblue. New cars like the Merc blue efficiency etc have SCRs and need to periodically fill up with adblue to keep the SCR happy, but anyhow back to DPFs.

A DPF has to periodically clean the filter. It does this by burning off the particulates when the ECU detects that the filter is full, this process is called regeneration. Regeneration can occur in two ways, passively or actively. PASSIVE regen is when the exhaust gases out of the engine are hot enough to cause the DPF to burn off the stored particulates, and conversely the other type of regen is ACTIVE whereby something additional has to happen to raise the exhaust temp high enough to burn off the particulates on the filters. 

The something else tends to come from burning additional fuel sometime before the filter in one of 2 main ways. 

In cylinder post injection is the first method, whereby additional diesel is injected through the existing fuel injectors into the combustion chamber very late in the combustion cycle (i.e. when the piston is close to BDC, bottom dead centre). When it burns, the energy is not converted into energy to turn the wheels but into heat energy in the exhaust gases. This raises the combustion gas temperature and hence the engine exhaust gases sufficiently to burn off the filter.
The second method is called HCI or Hydrocarbon injection. This is where diesel is injected into the exhaust via an additional fuel injector in the exhaust. When this burns it raises temperature in the exhaust and again causes the DPF to regenerate.

VMs would use either post Injection or HCI to regenerate, and both methods have drawbacks. It would appear that Honda have used post injection. The main problems with post injection are around effectiveness, service life and drivability, which I'll try to explain below, but it's worth mentioning these problems are more for Honda design engineers to sort out rather than things we should all worry about.

When you squirt fuel into the cylinder late (as a post injection) you risk squirting fuel onto the cylinder walls and the you get an increase in fuel found in your oil and hence reduced service intervals and specialist oils (so if Honda recommend an oil quality, I'd stick to it)
The other issue is that with in cylinder post injection whilst most of the post fuel burned is turned into heat, a bit of it is turned into energy to push on the piston and hence turn the wheels. The problem with this is that when the system regenerates the driver would notice a torque step which would feel like a small surge which is not desirable. Engines are generally calibrated so that this effect is combatted by a reduction in the main fuel quantity so no surge is felt.

So why is intervention required? When DPF is full and it not passively or actively regenerated (I.e. You haven't driven hard enough to passively regenerate, or the post injection isn't capable of increasing temperature to regen)  then a light or massage appears on the dashboard to tell the driver that he needs to do something before it becomes critical. Now i'm not familiar with how the 8th gen system works on the Accord, but there are two ways this could happen. Either a preset programme (if Honda designed one) will cause the DPF to regen stationary at theside of the road, or the driver will need to take their car to dealer and they will plug in their service tool and will force a regen in the workshop. 

So my advice to drivers of DPF equipped cars ... Give it a good thrashing every once in a while .... Like anyone needs an excuse ;-)

#45 JSW

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Posted 09 February 2011 - 09:33 PM

The latest epsodes in the saga are as follows:

The original warning light issue was in very cold weather in December. The light then re-appeared in mid Jan and took a day to resolve by driving for 20 mins at about 50mph. It then came on again last week and took about the same again to resolve. As it seemed to be happening more often I booked it into Holdcrofts last Monday. They had the car for about an hour and told me that they forced a regeneration and then tweaked the software so that the tolerances were a bit looser. They think this should sort things. In fairness to Holdcrofts they were very helpful. At times I do have a spell of a few days of short journeys, but this has always been the case and have had no issues until this winter.

Hopefully now sorted.

#46 beefy_634

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Posted 09 February 2011 - 09:50 PM

i think i did that regen?............were you waiting? the software wasnt the latest version, its just a ****** how long it takes to download the new one!. the latest software is desighned specificly for DFP function during stop start driving and short journeys. no doubt there will be other tweeks within the download but it is aimed at better DPF function. no doubt there will be more updates in the future.

#47 JSW

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Posted 10 February 2011 - 07:57 AM

Yep, sat and waited while it was done! Did a bit of work on my laptop in the meantime - are you the one in the reception area or the one who actually does the work? In any event I am well impressed generally.

Thanks.

#48 Chaz

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Posted 28 July 2013 - 03:20 PM

Have we had any more DPF issues seems to off gone quite of late i myself had a regen in February and have only done stop/start journeys since and have been waiting for the sign to reappear will go down the line of removal if/when comes on again. Have any members had this done recently???

#49 snapper69

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Posted 11 October 2013 - 11:36 AM

Just read one of the other posts about dpf problems, shame really as the nicest car I've seen for sale is a DTEC

Edited by snapper69, 11 October 2013 - 11:55 AM.


#50 Racy Jace

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Posted 11 October 2013 - 05:33 PM

Mine is an idtec and Ive had no problems yet touch wood. I used to drive from Dudley to Telford which was great. 50-53 mpg. Now Im working in Kidderminster doing way less mileage + traffic this time and getting 47-49 mpg. Its early days but after 8 weeks I've had no DPF issues yet. Just look at the type of journey you do and judge for your self if its worth the diesel.

#51 rhinogolf

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Posted 30 October 2013 - 03:38 PM

their is a new DPF udate now

#52 saj1987

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Posted 01 January 2014 - 11:25 PM

DPFs are just annoying. the 8th Gen accord 2.2 diesel DOES have a DPF as i found out the hard way. So about 2-3 months after purchasing my accord, by which time it had about 52-53k miles on the clock, there was a sudden warning light on the screen. The DPF was blocked. I had my local Honda dealer clean the filter and do whatever it was they had to do to get the car back to normal again at a cost of a few hundred quid (i cant remember exactly how much now).

Turns out if these cars don't get regular high speed driving the filter blocks up and stops working. The cost of getting it fixed every time is a few hundred quid minimum whether you take it to a main dealer or the local garage up the road.

I do not drive long distances daily so once a week i will take my car on a round trip around the M60 motorway just to make sure the car gets its fix of high speed driving. A shame really but i don't mind because it is a lovely car to drive, especially on the motorway.

I had the same thing go wrong on a 2008 Audi A4 that i had for a brief period. There was quite a difference. In the Honda i just got a warning on the dash, the car itself still kept driving normally. In the Audi though (it was a 2.0 tdi) there was a sudden loss of power. the filter had blocked up and stopped the turbo from working.........cost me £520 to get fixed from Audi (although that included a service that was due but with VWs fixed price servicing the bulk of the cost was the filter problem).#

So yeah, DPFs are a nightmare. But it doesn't get much better if you have them removed. If you take them out then your car will start chucking out black smoke like no tomorrow and all you smell is diesel burning! so if you don't like DPF then simply buy a diesel car that was never designed with such a part in the first place rather than removing the part from your current car.

#53 F6HAD

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Posted 02 January 2014 - 10:39 AM

The only time your DPF removed car will chuck out black smoke in the way you describe is if either you've removed it and not remapped it or it's been remapped by a cowboy who hasn't correctly DPF OFF'd the car.

The periodic emitting of plumes of smoke is the car going into regeneration mode and post injection maps having not been recalibrated correctly.

We do these and many other vehicles on a regular basis and have never had a single issue with regular cars and taxi cars passing their emissions test. As with anything in life, if done correctly, the job will be perfect.

And there's no way to really buy a diesel car with no DPF if you want a car that's less than 5 years old as most were fitted with them to comply with euro 5 standards.
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#54 shaun75

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Posted 22 January 2014 - 11:11 AM

https://www.gov.uk/g...ticulate-filter

 

Heres a link to next months MOT rule change regarding DPF filter & there removel, it seems it is just a visual inspection but i have heared a rumour that the emissions test is changeing to Plug in diagnostic testing on later model cars so no more smoke testing machines ???

 

 

 F6HAD can they really plug in through your OBD socket & check your vehicles emmisions ? This will put an end to DPF removel if so.


Edited by shaun75, 22 January 2014 - 11:17 AM.


#55 shaun75

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Posted 22 January 2014 - 11:46 AM

Just found this to confirm the rumour think its time to save up a refit a DPF.

 

http://cleanairinlon...-across-europe/



#56 jrd

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Posted 22 January 2014 - 04:58 PM

Do a lot of short journeys myself but have not had any DPF problems.I put it down to only using low saps engine oil and v power diesel.

#57 F6HAD

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Posted 23 January 2014 - 01:02 AM

There is no OBD testing that can show a DPF has been removed mate.  All they can see if they are really clever is targets and actuals, and of course when you map a car, the target values change anyway..


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#58 shaun75

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Posted 26 February 2014 - 02:25 AM

Just been for my 6 month Taxi test with the new DPF rules in place from this month i was interested how it would go.

 

My smoke test on the first throttle blip was over 3.65% :o  he then did 3 more blips of the throttle which averaged 0.63 ok well under the limit, but i just took a look at my cars first MOT smoke test before i owned the car & it was an amazing low of 0.03 this alone lets any tester know that no DMF is present & a sarcastic comment followed the test from the tester to let me know for now there's nothing i can do but i'm no fool.

 

The comment did include the very high first blip which obviously should not happen on a DPF fitted system.



#59 F6HAD

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Posted 26 February 2014 - 08:54 AM

Bear in mind your car has also had its cat removed Shaun, which is also going to make a difference. Also its running an unknown tuners software (which might be absolutely fine) but could also be contributing to the smoke.

still well within limit though.

also the fact you had such a low reading pre removal would also indicate a blockage starting to happen.

might be better for the environment but not great for your car or wallet.
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#60 shaun75

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Posted 20 March 2014 - 05:15 PM

Oh dear another nail in DPF removal coffin, Insurance company's could void your insurance if you don't declare the Modification to them.

 

Friend read it in Car Mechanics there's a 6 page spread on the issue.

 

Terra-clean have launched a non invasive cleaning system around £200 with very positive results looks like that's the way to go as the Government are finally piling on the pressure, that's going to cost me big time to refit & remap bad move but you live & learn.

 

This is the local Warrington agent great lads too.

 

http://acemm.co.uk/terraclean.htm