How Clean Can A Diesel Be?

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E55BOF

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I've posted this elsewhere, but I'd like the widest possible readership; I hope the mods won't mind.

I've just checked the DPF figures on the 2013 OM642 CLS with my iCarsoft MB II.

Soot content 0%.

Ash Content 0%.

Mileage since last DPF Regen: 57

Here's where I really start to worry...

Mileage since last Ash Content Correction - 68,043. The car is only showing 68,223 miles from new! There's nothing in the MoT history to suggest the car has been clocked, and I'm pretty sure it hasn't.

The car does mostly longish runs - 20 miles a time, with occasional 100 mls + trips.

There is also a figure shown as Total Distance - 5,747. There is nothing to indicate total distance since what, or before what. Anybody know what this figure is?

I don't know a lot about diesels, but is it possible the DPF self-cleans itself of ash as well as soot? Or do I have a system fault?

(All the numbers are actually shown in km, but I've converted them to statute miles).
 
There shouldn’t be much ash in the DPF anyway as you’re using low ash oil? No expert on this, just trying to think out loud. 🤔
 
If you drive the car favourably, which is seems you do, then you won't generate much soot.

Regens should burn all the soot off so with a very recent regen a soot content of 0% is plausible.

Ash is usually a calculated/estimated value.

If you have been keeping the soot down then there won't be much ash but 0% is a bit suspect. It could be the code reader is struggling with the format of the data the car has sent it.

A would guess that an "ash content correction" happens when someone (using diagnostics) resets the figure. That should happen if the DPF is replaced for example. It could also happen if someone using diagnostics clicked the wrong box or perhaps if the car had a full software update.

In my other car I cleaned the DPF myself at around 120k miles and there wasn't much ash in it.
 
:dk:. There are no fault codes, but I just find it almost impossible to believe that any engine, diesel or petrol, could be that clean after nearly 70K miles. Thanks for that, Jason; helpful and encouraging. Perhaps I'm worrying unnecessarily.
 
Just out of interest why are you scanning the car on iCarSoft? Is there a fault with it? 🤔
 
Looks normal to me, its just working as it was designed.
Probably take the mileage with a pinch of salt, mine says hasn't had a regen for over 70,000km, but the regen was done just before these figures were displayed.
I imagine the results are estimated purely on the accuracy of the various emission sensors, not to be taken literally.
levels.jpeg
 
Just out of interest why are you scanning the car on iCarSoft? Is there a fault with it? 🤔

Does the car need to have a fault, for an enthusiast to scan it with iCarsoft.....? I prefer to say that I am connecting with my car.
 
Is the mileage displayed on icarsoft not the total mileage when last regen'd?
 
Just out of interest why are you scanning the car on iCarSoft? Is there a fault with it? 🤔
No, there's nothing wrong with it, but as it's a diesel with a DPF, and DPFs are prone to gunking up and costing an armannaleg to fix, and I've only had the car for a month or two, I'm establishing a baseline. Looking good, too.
Looks normal to me, its just working as it was designed.
Probably take the mileage with a pinch of salt, mine says hasn't had a regen for over 70,000km, but the regen was done just before these figures were displayed.
I imagine the results are estimated purely on the accuracy of the various emission sensors, not to be taken literally.
That's not a regen figure, that's an ash content correction figure; they're not the same thing. My same parameter figure is 108,869 km.
 
Is the mileage displayed on icarsoft not the total mileage when last regen'd?
No; that would be 68,166 (68,223 - 57), and it's not, it's 68,043.

A regen and an ash correction can't be the same thing, because ash is what is left after a regen. That's all I know; I don't know what an 'ash correction' actually entails, but I'm guessing it's some kind of STAR reset procedure, because it seems unlikely the car would have required a physical emptying of the DPF ash content only 200 miles or so from new.
 
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Just checked mine again, last correction of ash is 44846
Car mileage is 44989
Difference of 143 miles. So I guess it’s not accurate.
The main odometer reading on the Icarsoft is dead on with 449897D351F53-2AE8-422B-BA48-3D611D27C983.jpeg
 
Making sense of your sensors: DPF differential pressure sensor | Delphi Auto Parts

These are pressure derived figures. Equal pressures means no restriction by DPF deposits. Likewise the differential sensor cannot distinguish between ash and soot back pressure and the ash figure would be derived from the difference in resistance to flow before and after regen the assumption being regen removes the soot--- any residual resistance being down to ash. Whats your exhaust pipe like- is it black?
Only way to check for sure is to get the car on a system that measures exhaust composition directly as in an MOT test centre. the sensor may be faulty-leaking connections or even a gutted cat.
 
Thank you for that. The car had its MoT just before I picked it up. The coolant temperature was 60 degrees (the thermostat was faulty). The car had covered 66,778 miles then, but I have no way of knowing how long the 'stat had been faulty; it was replaced at 67,339 miles. The car has covered 68,223 miles now. Yes, the tailpipes are sooty inside, but could that be from the period when the thermostat was faulty, which ended 900 miles ago?

The car runs well, and does about 32 mpg on a 20-miles-each-way commute (starting from cold each time) and I get 36 mpg on a long motorway run cruising at, er, allegedly 85 mph.

(I've said before, I don't know much about diesels...). The MoT smoke opacity figures on four runs were: 1.05, 0.39, 0.32, 0.27. The mean (of the last three) values used for the test was 0.31, against a plate value of 0.50, so it passed. Does that sound reasonable?

The last regen for the DPF was 57 miles ago, so it is regenerating. My soot and ash figures aren't far off those for Geoffus in this thread, and another member in this thread: 2013 CLS 350 OM642 - Is This Possible? | Engine, which is encouraging.

I still don't know what a 'correction of ash content' is, but it plainly isn't a simple regen. Does anybody know what it entails?
 
The MoT was done at Mercland, so no qualms there.

The smoke opacity test figure at its first MoT in 2016 was 0.29, so I think it's OK.

I'm not much worried, but I'd still like to know what the 'correction of ash content' entails; it's bugging me...
 
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Couldn't find anything on t'internet, but I did find this, in a 'What Car' article:

"There are two types of regeneration: passive and active. Passive regeneration normally takes place at higher speeds, when the engine is running at higher revs. To make sure that the regeneration takes place, most manufacturers suggest that every few hundred miles, the car is driven for a period of more than 15 minutes at a consistent speed in excess of 40mph. Doing this should clear the filter."

My car does that more like every fifty miles at most, and more like in excess of 70 mph, so if that's correct I don't have to worry at all about the DPF clogging up. Hurrah!
 

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