ash content in dpf

[magentalic]

ran a on diagnostic on my mercedes c220 cdi and it is reading 94.4% ash content in the values list not a fault code,sounds high obviously can anyone shed any light on what to do about it.

 

[ash59fifty-uk]

Forced regen? Spiritual trip down the motorway?

 

[400ixl]

Three possible contributors of this:

1. Oil which should be the low ash specification
2. Fuel, although you have little control over that (and before anyone trots out the supermarket fuel BS, that is no different to others)
3. Driving conditions, the DPF needs certain conditions to do a regen

You can get DPF cleaning additives, maybe try one of these and then take it for a good long blast at a decent constant rev range. Best to be in the 2,000+ rpm range for 20-30 minutes really to try to get it to do a full regen.

Other way is to use software to do a forced regen.

If none of that works, you could be into manually cleaning or even replacing.

Other thing to be checking is that the EGR valve is functioning correctly and not recirculating when it shouldn't be.

 

[markjay]

ran a on diagnostic on my mercedes c220 cdi and it is reading 94.4% ash content in the values list not a fault code,sounds high obviously can anyone shed any light on what to do about it.

While intuitively 94.4% sounds high, does anyone know what a 'normal' reading would be? Might be worth confirming first just how unusual - if at all - the current reading is.

 

[400ixl]

Usually find thye try to regen in the mid 80's, sometimes lower if the conditions are right.

Problem you have is that if the regen has failed several times it can be tircky to get it to want to restart the process automatically.

 

[Rory]

Surely if it's full of ash it needs cleaning or replacing?

How miles has the car done?

 

[400ixl]

Regen is cleaning. It burns the ash and particulate off through the exhaust system.

 

[grober]

Technically hinges on the definition of ash as opposed to soot.
Ash = the inert powdery residue left after the burning of a substance.
This would imply ash cannot be removed except by mechanical means.
This opposed to soot which is a partially combusted organic material which should be able to be removed by burning off?
I suspect the terms are interchangeable as used in this context but if not ash can only be removed by mechanical means.
You perhaps need to find this out before deciding the best solution.

ps On thinking a bit more about this I guess its possible that the ash might be held in a matrix of soot and burning off the soot might free the ash?

pps 94.4% ash content does sound fairly choked up!

 

[magentalic]

thanks for the replies.the car has done 116000,strangely enough it is a 2004 model so i was suprised to see it had a dpf fitted.i have tried a high rev burn out but i was holding about 4000 revs when i just took off on its own and over reved then blew intercooler pipe off and i thought i had done major damage however it had damaged all the injectors,i had them tested and refurbed and apart from a missfire it sounds ok again.i am trying to determine the cause of the missfire hence the obd check.

 

[400ixl]

Check the oil level immediately. Failed regens can mean that diesel has entered the oil system and this has risen to the point where it blows back into the cylinders which causes an overrun and can do damage.

 

[Rory]

I suspect the terms are interchangeable as used in this context but if not ash can only be removed by mechanical means.

They're not inter-changeable, although of course it's possible that someone is saying the wrong thing.

I'm not sure on MB's (mine doesn't have a DPF) but our recent EU6 VW does, and IIRC that does a forced regen at 45% soot loading or maximum 465 miles.

The dpf in that car doesn't hold an awful lot of ash - VW size them to do approx 100K miles. If that's an industry standard goal then it fits pretty well with where the OP is.

 

[magentalic]

Check the oil level immediately. Failed regens can mean that diesel has entered the oil system and this has risen to the point where it blows back into the cylinders which causes an overrun and can do damage.

yes i think that is what happened when i tried before it was just like a nitro boost(i imagine) and it over reved.i have checked the oil level and it is ok.

 

[DieselPete]

If you service your car yourself and dont re set the service indicator the car will stop auto regenerating. May be worth knowing

 

[magentalic]

update......took the car in to mercedes specialist with star diagnostic he did a forced re-gen and health check £45 + vat all ok now.

 

[400ixl]

Good to hear, thanks for giving an update. Were you there when they did the forced regen? Makes you toes curl to have it sitting there revving away at what sounds quite a rate for so long.

Did they say what % it has brought it down to?

 

[magentalic]

hi,no i left it with them,i thought he said ash was zero and had brought the soot down to 40 odd % but i may be wrong,i will check it with my snap-on tommorow

 

[magentalic]

just checked and ash content is zero.