Technical DPf clogging normal level

[doblojohn]

Hi,
I have a Doblo 1.3 multijet t/diesel 2008.
At 19,000 miles it did a DPF regeneration with warning light coming on.
That went out but later the oil degradation warning appeared.
I immediately changed the oil, bought Fiatecuscan and took a look.
The Particulate filter clogging was 98.56 percent.
I then reset the oil degradation warning and carried out a Forced regeneration, this worked and brought the Particulate filter down to 83.50 percent.
So my questions are (please).
1. Is 98.56 percent very high and what is an acceptable level.
2. Would it be bad to repeat this procedure to bring it down further.
3. Should I remove the DPF and clean it and put it back.
4. What should the Differential pressure sensor reading be ( I am guessing this also gives an idea of how blocked it is ).
The car actually runs well and I haven't noticed any problems.
Thanks for you help.
john.

 

[Poperon]

Good post.


Love 'em or hate 'em, DPFs are probably here to stay (for the moment). They may not seem to work very well but presumably the designers have worked out that they can – but I fear that the end users haven't been let in on all the secrets of how to live with 'em.




I'm only a layman but as I understand it:


Scheduled Regeneration...If the conditions are favourable and the built in regeneration schedule can be performed (and completed) then a DPF should not require any further maintenance and should last 150,000 miles.


The DPF built-in regeneration is triggered when a “clogging” level is exceeded. This is derived from the difference in exhaust pressure across the DPF which is measured by sensors mounted on the DPF.


DPF Regeneration Process...In short, the regeneration process involves injecting an excess of diesel into the cylinders which, on combustion, results in a higher than normal exhaust temperature and thus a higher temperature in the DPF sufficient to “burn off” filtered deposits and eject them as harmless compounds from the exhaust system.


The act of adding additional diesel to the cylinder can (and probably will) result in some diesel passing by the piston rings into the sump and contaminating the engine oil. The engine oil can only accept a certain amount of diesel contamination before its lubricating properties are diminished below an acceptable level.


The ECU will only allow DPF regeneration if the engine oil quality is good enough to continue to do its job under the higher engine temperatures which exist during DPF regeneration. Oil quality is based on an algorithm of: time since last oil change, mileage since last oil change and the number of DPF regenerations since last oil change.


Oil Change Check...If the engine is telling you it needs an oil change then it will not perform a DPF regeneration.


If the oil is changed and the oil change status is not reset in the ECU then the ECU still thinks you have worn out oil and the DPF will not regenerate but will continue to block up. I imagine this can be a major source of DPF clogging up and ultimately failure.


Going back to Doblojohn's questions:


I've heard of examples of clogging percentages ranging from 20% up to 135% (presumably using FiatECUScan or similar). Since one would expect 100% to be fully clogged one can only assume that these figures have a slightly more arbitrary base line to convention.


Q...Is a reading of 135%+ indicating a fully clogged DPF?


Q...As DPF regeneration is triggered by a high inlet to outlet DPF pressure difference can anyone say what this is in DPF clogging percentage....would it possibly be 100%?


Q...If oil is changed when required and the scheduled regeneration is allowed to finish and the engine runs well with typical fuel consumption, then is there any need to monitor DPF clogging levels and induce DPF regeneration if the clogging level is rising but not to an unduly high level?


Cheers


Ron

 

[Caravadossi]

From HJ's site ...

“From a Vauxhall Owner's Forum, but generally very helpful advice that applies to most first generation self-regenerating diesel particulate filters ('closed loop' DPFs are more sophisticated):-

Question: The glow plug symbol is flashing. Why? What should be done?

Answer: The DPF regeneration has not been completed during normal driving and now DPF has reached its maximum saturation at which it can still be regenerated. The limit value depends on variant and Model Year, but is in the range of 105% - 125%. Possible causes for this are:

a.) Frequent short distance journeys, i.e. high soot loading while at the same time regeneration of the DPF does not take place because the conditions necessary were not fulfilled.

b.) Frequent interrupted regenerations, i.e. the engine was switched off during regeneration. Applies to short journey drivers who have at least fulfilled the conditions for triggering regeneration. If the glow plug light flashes, the vehicle

a.) Engine running since start for longer than 2 minutes.
b.) Calculated saturation higher than 80%.
c.) Coolant temperature over 70°C for at least 2 minutes.
d.) No DPF-relevant faults stored in system.
e.) A defined vehicle speed threshold must have been exceeded (e.g. for >80% loading, 100 km/h).”

See full text at:
http://www.honestjohn.co.uk/faq/diesel-particulate-filters/

20111029

 

[Vento]

I then reset the oil degradation warning and carried out a Forced regeneration, this worked and brought the Particulate filter down to 83.50 percent.

Dear doblojohn
How did you start a forced regeneration?
Thanks in anticipation
Vento

 

[doblojohn]

HI
I used Fiatecuscan.
But if you are thinking of doing this I would advise you take a look around to see why or how often this has happened before,---- by this I mean the history of your DPF.
Also take a look at the oil degradation before you consider this --- as Poperon mentions above it can all be linked.
John

 

[Wheaty]

I guess having a normal 1.9JTD none of the above aplies to me...

However this has been a very informative and interesting post Its nice to have some technobable

My Wife on the other hand would lean over about now and say something about "135%? You cant have that. Its either 100% or less than 100%" Ahh Scientists

Wheaty

 

[johnhififan]

There's nothing wrong with a percentage greater than 100, it depends on context, ok I cannot eat 200% of a pie but I can eat 200% more pies than yesterday.
In the same way improper fractions(where the top number is bigger than the bottom) are allowed. pi=22/7
Mmmm pies.

 

[Wheaty]

Exactly, that most of the time the context is either wrong, or the point of reference is wrong, which is what winds her up.

And in this case a filter is either full or empty..or the measurement is something else entirely...hence 135% seems silly

.. Oh and stop it with the pies! I've not been to my favourite pie shop in a few weeks!

 

[doblojohn]

Hi,
Here is an update.
I have contacted various Dpf experts or at least people who claim to have some knowledge.
I have also contacted three Fiat dealerships and none of them had this technical information and in most cases I seemed to know more then them (worrying ?).
I have carried out another forced regeneration of my Dpf and concluded that in my case for my model ---
Forced Dpf regeneration reduces the clogging level by around 10 percent.
Forced Dpf regeneration degrades the the oil by around 2 percent.
My gut feeling is that Forced regeneration is not too good for the engine as it seems to generate quite a lot of heat and I wonder about the effect on the exhaust valves.
Is there no one out there who knows what the normal / acceptable Dpf clogging level should be.
John

 

[doblojohn]

Hi
Wheaty
Doblo 1.9 JTDs have DPFs as well, Unless you have one that was manufactured before.

John

 

[Yobbo]

I wonder how long it will be before someone offers a service where they remove your DPF and run a gas burner through it at the right temp or maybe or chemical process to clear it out and then refits it for you. It would surely be less expensive than some of the stupid prices being quoted for DPF replacement that one hears of.

 

[TwyRob]

Hi
Wheaty
Doblo 1.9 JTDs have DPFs as well, Unless you have one that was manufactured before.

John

The 105 Multijet has not got a DPF and all of the pre 2005/6 facelift models are without DPF too.

It's the 120 Multijet to worry about really.

 

[TD5]

Last time I looked mine was about 17% clogged.

if you were interested in comparing FiatECUScan params I recorded mine here a few months ago:-

https://www.fiatforum.com/doblo/268016-oil-degradation-reset-tool-2.html

If I get chance over the weekend I'll take a look and see what it's sitting at now.

ATB

Peter

 

[leeparks]

I have just been through the DPF nightmare.The exhaust downpipe that joins to the DPF was blowing on the flexi part so I had it renewed. This immediately triggered the DPF warning (code P2002). I tried the usual tricks to do re-gen ie: 85 miles of high speed motorway travel to no avail so I went back to the exhaust people and asked them to check that the new pipe had no leaking joints., It was ok but a leak was found where the pipe meets the silencer so I had this replaced, too kit for another run (45miles) and the fault cleared. It came out of limp mode and after re setting the warning light it seems to have cured the problem.

 

[t1tmt]

Mine has been in a pretty permanent limp mode the last few days, took a look underneath and the flexible joint is blowing. Makes sense, and looks like I know what I'm doing next day off.