Author Topic: Discussions about DPF  (Read 109558 times)

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Offline Steve_c

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Re: Discussions about DPF
« Reply #30 on: January 23, 2012, 07:04:21 pm »
I apologise if this is old news to people, but I did a fair bit of investigation on DPFs after I bought my Mondeo, and it appears that there are three types;

cDPF (c=coated). This is the type fitted to the MK4 Mondeo TDCi (Peugot engine, apparently). This type "regenerates" as / when required by heating up to burn out the ash that has accumulated in the filter. This process does not use any additional additives.

Additive type. Used on Ford Focus diesels (around 2008) and presumably many other cars. A sensor in the exhaust system measures the internal exhaust pressure, and at the specified limit injects a small dose of additive into the DPF where it ignites, elevating the temperature of the DPF to remove the trapped ash. This additive apparently requires replenishment every 37.5K and is horribly expensive.

Fuel type. I believe this is the type used by Mazda, Mercedes and others. Essentially, a small amount of diesel fuel is deliberately injected into the cylinder on the exhaust stroke. This fuel is not burnt in the cylinder, but is forced out past the exhaust valves and enters the exhaust system. When the exhaust gets up to temperature, this fuel is combusted, raising the exhaust / DPF temperature to burn out the ash. This is presumably why you would need to maintain engine RPM at 2000+.  I don't know whether the fuel is injected on every exhaust stroke.

The problem with this method is that some of the fuel is forced past the piston rings and into the sump due to the internal cylinder pressure. A few years ago, this would have been fine, as the diesel fuel was sufficiently volatile to simply evaporate away. However, the government (obviously experts in such matters) decided to increase the permissible level of "bio-fuel" in diesel. Unfortunately, bio-fuel isn't particularly volatile, and doesn't evaporate away - it just sits in the sump contaminating your engine oil and, more importantly, continually adding to the volume of fluid in the engine. As the volume increases, so does the crank-case pressure.  The obvious down-side of running at higher revs to raise the exhaust temperature is that more fuel will be forced past the rings into the sump.

As the pressure increases, if the fluid level is high enough, oil / bio-fuel mix can be forced upward back past the piston rings where it ignites. At least, that's how I understand it - I'm quite happy to be proved wrong (I want a Mazda 6 for my next car!).

Offline doninphi

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Re: Discussions about DPF
« Reply #31 on: January 23, 2012, 08:41:28 pm »
That all makes sense.

So how does my 09 Mazda show when the fuel/oil mix gets bad like this? I know when the DPF gets blocked the DPF light comes on, but is there a light I should look out for in the event of the engine oil becoming too contaminated?

Ta.

Offline ColinB

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Re: Discussions about DPF
« Reply #32 on: January 23, 2012, 09:30:49 pm »
You need to check the dipstick regularly. In addition to the usual F(ull) and E(mpty) marks, there is one further up marked X. If the oil level approaches the X mark then you need to change the oil as there is too much diesel in it.

I have a 2.2 diesel and the DPF arrangement has been improved over the 2.0 diesels which reduces the likelihood of sump comtamination. My TS2 is now approaching 2 years old and in each year the oil level hasn't budged between annual services. My driving pattern is mixed but usually includes 15 miles or so on a dual carriageway at 60+ mph once a week and this seems to have kept the DPF happy so far!

Offline Steve_c

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Re: Discussions about DPF
« Reply #33 on: January 24, 2012, 07:13:59 pm »
Sinspeed told me that they would "guarantee" that the car would not fail the MoT test on emissions as a result of the DPF removal

As I understand it, there isn't an emissions test for Diesels in the same way as petrol engines.  If that's the case, it's a pretty easy claim to make.

Having re-read some of the previous posts, I'm a little confused.  IF the problem on the 2.0 litre engines IS caused by fuel being injected on the exhaust stroke and forced past the piston rings, it doesn't seem logical that removing the internals from the DPF housing will do anything to resolve that problem.  Unless reprogramming the ECU prevents fuel being injected on the exhaust stroke?

From other forums, I've read that modifications to the ECU will constitute an MOT failure from some point during 2012.  I have no idea how the testing station would determine whether the ECU / fuel map has been changed, but I wonder how a car with a reprogrammed ECU would fare under the new rules.

Offline PieEater

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Re: Discussions about DPF
« Reply #34 on: January 26, 2012, 04:58:36 pm »
Do the new models suffer from this issue?  Just thinking ahead about my next car and I like the styling on the new 6  :)

Offline PEH

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Re: Discussions about DPF
« Reply #35 on: January 30, 2012, 04:34:02 pm »
I've found this forum to be very informative and joined the mazda campaign forum as well.
My Mazda 6 experience has been mixed, but now feel that I am coming to terms with the 'quirks' of this DPF design issue.
Brief summary of other posting:

The DPF light first started flashing in 2010 and I had it serviced independently. The DPF light remained flashing and my garage (I had used them for years and have found them trustworthy and reliable) advised me to take it to another independent outlet to get the DPF "regenerated", which I did.
All remained well till service needed in October 2011. The DPF light was flashing prior to service and this time a different independent carried out the service and "regenerated" the DPF.

All appeared well until I was on a longish journey in early January 2012. I was driving on the M6 (in 6th gear) after around 90 minutes drive time, when the engine power dropped off on an incline. I dropped down the gears 5th then 4th until the road levelled off and power came back.
This happened a few times, then the DPF started flashing.

The DPF continued flashing and I nursed the engine so I could get home (around 60 miles). Then the amber engine warning light came on close to home.
As I was close to home, I nursed the engine even more and parked the car on my driveway.
I have covered less than 3000 miles since the service.

I contacted a local dealer who was helpful (that surprised me). The dealer told me that the oil level has to be reset electronically after an oil change (that precludes any DIY work). The independent pointed me to a different independent.
I've been to that one today and the DPF and warning light has been cured - for now at least.

Both independents and dealer are Leeds based. I will transfer allegiance to the one I visited today.

Hopefully this will help someone else.

Garage website www.motocity.co.uk

Offline m.j.holroyd

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Re: Discussions about DPF
« Reply #36 on: February 07, 2012, 08:04:16 am »
O.k here we go with another D.P.F issue.Alot of my motoring is local (not the best choice of engine i now realise) I've only owned the car for 10 days and the dreaded D.P.F comes on. solid not flashing. Read the handbook took the car for a good blast up the duel carriagway approx 26miles round trip.Kept the car in 5th as to keep the revs over 2000.The light DIDN'T go out.Stopped the car re-started no light.Harrah,i thought only for it to return 10-15 mins later.The car is due a service for which is being done thursday 9th. Is the light coming on as a "service reminder" and do i need to instruct the independant garage anything.E.g re-setting the oil level electronically. thanks in advance. Michael

Offline ColinB

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Re: Discussions about DPF
« Reply #37 on: February 07, 2012, 09:00:53 am »

Offline StaceyR

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Re: Discussions about DPF
« Reply #38 on: February 29, 2012, 10:13:14 pm »
I also have a mazda6 with dpf problems, have had the DPF replaced less than a month ago but now got flashing light (wasnt on still first) and engine management light, went to my own garage who says the egr valve needs replacing at a hefty cost.  Could he be right, he has put some cleaner in it at the moment and told me i am ok to drive and the light might go off.  I thought it just needed regenning but he says that is not the case.  Please tell me I am not damaging my car by driving it.

Thanks

Offline m.j.holroyd

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Re: Discussions about DPF
« Reply #39 on: March 16, 2012, 06:23:17 pm »
Ahh,Stacey i feel your pain. I too had a flashing d.p.f light along with engine management light. All i can tell you is that i was advised by Mazda "NOT TO DRIVE THE CAR WHILST THE D.P.F LIGHT IS FLASHING" . I can also inform you that, if you have the "engine management" light up this will throw up a fault code on any reputable garages diagnostics equipment. I can only speak from my own experience, as i am no mechanic. Hope this helps.

Offline MicBarra

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Re: Discussions about DPF
« Reply #40 on: April 16, 2012, 09:45:06 am »
Ey up ladies and Gents,
As most of you know i have had my TS 2.2 since end of Feb and during which time i check my oil level. The last time i checked the oil level it was spot on the F level but I had then checked it y'day it is on the X mark... So thinking this just could be the DPF i took the car for a 40 minute spin down the A19 at 2500 revs, got back home, waited a few hours and then checked again, but the oil level hadnt changed.
I have received a letter from a Mazda dealer indicating that my service is due but i get 2 years free service with the car from the dealer i bnought the car from. So i have booked the car in for a Oil and filter change.
Should this keep the DPF problems at bay or am i in for a bumpy ride?

Cheers
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Offline m.j.holroyd

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Re: Discussions about DPF
« Reply #41 on: April 21, 2012, 06:12:34 pm »
Hi, before we start,like i have said in previous posts i am NO mechanic,so,don't take this as gospel.
The reason your oil level rises is because this is how the d.p.f regens.There are posts on here that go into much more detail.
Taking it for a run will not make the oil level go down.The oil level rises gradually between services,once it reaches the X mark get it booked in. Hope this helps.

Offline ColinB

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Re: Discussions about DPF
« Reply #42 on: April 22, 2012, 08:06:28 am »
Quote
The oil level rises gradually between services,once it reaches the X mark get it booked in. Hope this helps.

Not necessarily, it depends on what sort of driving you do. If your oil level has risen as quickly as that then it suggests that you are just doing a lot of short runs or that there is something wrong. But you certainly need to get the oil changed asap if it is up to the X mark.

I have had my TS2 2.2 for two years (I do about 9k per year) and the oil level didn't move between changes but it does get a decent run at least once if not twice a week.

Offline MicBarra

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Re: Discussions about DPF
« Reply #43 on: April 23, 2012, 08:09:16 am »
Oil level has been changed but due to be being pretty ill ive been unable to check the work over lol....
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Offline Pgregs1

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Re: Discussions about DPF
« Reply #44 on: May 11, 2012, 09:44:55 am »
Hi Rob,
Yep it’s pretty straight forward. Remove some of the air hoses and then just 4x12mm bolts, as long as you have a good set of 6 sided sockets to get a good hold of the bolts on their flat edges.
Two from the EGR cooler and then the two mounting it on to the engine had to use a mirror to see the lower one.
Once you have it out the only tricky bit is removing the solenoid/motor as it held on with 4xPhilips screws which can slip if you don’t put it in a vice, but there's just enough room to get a grip on them with a good vice-grip if you do get stuck.
The valve stem can then be removed by compressing the spring to release the retaining clips. To clean it and the valve seat I used a dremmel with a wire brush attachment to do the cleaning.
Be careful though where the valve stem enters the main body of the valve as this uses a wire mesh as the seal and is awkward to clean(more a washing & rinsing process) plus you don't want to deform it or one of the wires in the mesh as they may obstruct the operation of the valve.
After this it was actuating as smooth as silk while and closing fully before I cleaned it I had to gently tap the valve out with a small hammer it was so sticky and you could still blow through it when closed. I dread to think how tight it was when the engine was up to temp.
I plan on taking it out again soon to see if there has been much build up and as its so easy to do I would check it at least once a year to help avoid DPF issues.

Cheers
that sounds a good idea im not very mechanically minded but may take mine to my local garage and get it done there & watch them do it then next time maybe do it myself ,anyone know how much a garage would charge to do this ??