[_TB_]

How does the ecu calculate the amount of soot in the DPF? It is based on the input from the differential sensor?

Reason I'm asking is that I have an errorcode 480 for clogged DFP. Carly states that there is 45g of soot in the DPF (ash is 44g). I have forced a regen several times and I can see that it regenerates - but the reported soot level does not change by more than ~3g. I tried to drive 80km @ 3.100 rpm (115km/h in 4th) while forcing a regen. I also tried to drive in 6th for 80km while regenerating. But the soot levels stay the same. :/

If the soot levels are calculated based on the pressure sensor - I could be looking at a faulty pressure sensor, and not a clogged DPF.

Anybody knows? E91 325d

[Yozh]

It's a plausibility between the ambient pressure sensor (inside DDE), your boost pressure sensor, exhaust back pressure sensor and the differential pressure sensor. There is s job that can check all, will try to find a name for you. I am not sure if on your 325d you have a differential sensor or two separate ones, front and back. Also check your tubes are all well attached. Run the parameters on all the relevant sensors and you will be able to narrow it down.

[ingenieur]

Also - I'd make sure the engine is reaching full operating temp. If the T-stat is bad - and the ECE diesels also have one for the EGR cooling - and the engine is always under 80 C - that could contribute to higher smoke. Stock engine without tune?

[_TB_]

Originally Posted by Yozh

It's a plausibility between the ambient pressure sensor (inside DDE), your boost pressure sensor, exhaust back pressure sensor and the differential pressure sensor. There is s job that can check all, will try to find a name for you. I am not sure if on your 325d you have a differential sensor or two separate ones, front and back. Also check your tubes are all well attached. Run the parameters on all the relevant sensors and you will be able to narrow it down.

325d only has one pressure sensor - before the DPF.. checked the pipe for it, no cracks or leaks. the coolant goes up to about 95C when diving around.
I do have an error on the aux water pump though.

soot level is down to 26,5g now, but pressure before DPF is still high :/

[Yozh]

This thread may be of interest. If you are in Chrome it will translate it for you and you should get a general idea.

http://www.e90-forum.de/e90-e91-e92-...t-gemeint.html

[_TB_]

Originally Posted by Yozh

This thread may be of interest. If you are in Chrome it will translate it for you and you should get a general idea.

http://www.e90-forum.de/e90-e91-e92-...t-gemeint.html

Thanks

..However they talk about the LCi that has a front and rear sensor - the non-LCI only has one.
I guess it calculates it from the atmos sensor, the MAP sensor and the exhaust pressure sensor.

Perhaps i should check the readings from the MAP sensor and the atmos sensor to see if they are plausible?

[Nadir Point]

I'm still not warmed up to the idea that all these sensors and plausibility calculations always contribute to things working as expected, or not as the case may be. Why not a simple drive pressure/boost pressure differential with plausibility?

[DWR]

Originally Posted by _TB_

How does the ecu calculate the amount of soot in the DPF? It is based on the input from the differential sensor?

Reason I'm asking is that I have an errorcode 480 for clogged DFP. Carly states that there is 45g of soot in the DPF (ash is 44g). I have forced a regen several times and I can see that it regenerates - but the reported soot level does not change by more than ~3g. I tried to drive 80km @ 3.100 rpm (115km/h in 4th) while forcing a regen. I also tried to drive in 6th for 80km while regenerating. But the soot levels stay the same. :/

If the soot levels are calculated based on the pressure sensor - I could be looking at a faulty pressure sensor, and not a clogged DPF.

Anybody knows? E91 325d

Ash cannot be removed by regeneration. Eventually, ash will fill the DPF and end its useful life. This is the reason for using oil and fuel that minimizes the accumulation of ash. The DPF can be back flushed to clear the ash. I've seen it done in a DIY manner with a pressure washer.
Now, the DDE cannot accurately measure ash. It makes an estimate based on regeneration effectiveness.

[DWR]

Originally Posted by UberArchetype

I'm still not warmed up to the idea that all these sensors and plausibility calculations always contribute to things working as expected, or not as the case may be. Why not a simple drive pressure/boost pressure differential with plausibility?

If you are not warmed to the idea, why propose something that is even further removed from true cause and effect? The boundary of plausibilty for boost vs drive pressure involves a complex relationship that includes other variables. I agree that not all the plausibilty criteria are robust. However, the most critical sensors often have checks based on 2 other sensors. The real probem is once you start modifying things the boundaries of plausibility often need to be modified ... or removed.

[_TB_]

Originally Posted by DWR

Ash cannot be removed by regeneration. Eventually, ash will fill the DPF and end its useful life. This is the reason for using oil and fuel that minimizes the accumulation of ash. The DPF can be back flushed to clear the ash. I've seen it done in a DIY manner with a pressure washer.
Now, the DDE cannot accurately measure ash. It makes an estimate based on regeneration effectiveness.

Yup. Ash is still reasonable - up to 100g is considered ok as far as I know. When starting to touch 100g - the DPF needs replacing. I'm at 45g.

One funny thing, I just stubled across a Carly log I did in Feb. Here soot levels are at 30g (I'm at 26g right nok) - I also have a log with the pressure before the DPF - I'll try to make the same log today to see if I have the same pressure now as before.

[_TB_]

Hmm I'm maybe getting closer.. today it threw a 03F25 error (Charge air hose monitoring) error. Seems there is a gremlin og gunk in my sensors.
The car drives fine, has normal power and revs fine to 5.000 - so I do not think the filter is actually blocked - but it might be due to dodgy/dirty sensors.

[Nadir Point]

Originally Posted by DWR

The boundary of plausibilty for boost vs drive pressure involves a complex relationship that includes other variables.

That's exactly what makes it a better reference point. It produces a data point from multiple inputs, but only 2 sensors. Call it removed or whatever you wish, but it's a more "plausible" way to get better data, more easily and reliably.

[_TB_]

small update from me. I have been driving with a very light foot, and keeping a very steady speed all the time. this has helped, today I got the burnt rubber smell as it did the big regenerate program. error codes are gone and soot is down to 8g. pursue is now 8mbar at idle.

[DWR]

Originally Posted by UberArchetype

That's exactly what makes it a better reference point. It produces a data point from multiple inputs, but only 2 sensors. Call it removed or whatever you wish, but it's a more "plausible" way to get better data, more easily and reliably.

When there are multiple pathways to the same output, plausibility is less reliable. The data you will get is aliased, by definition. The result is less information.

Let me give a simple example. Suppose we want to know whether either of 2 sensors is out of "calibration". One sensor's output must be between 5 and 9, the other between 11 and 15 (you pick the units). Now let's make a plausibility test that follows the line of thinking you presented. Let's measure the combination of the 2 sensors. Plausibility for the sum of the 2 sensors is between 16 and 24. However, the sum of 3 and 20 are within the plausibilty limit, yet both senors are out of "calibration". That's why the OEMs have not done what you have proposed.

More sensors has been the trend in engine control. I do think the idea that more direct measurement methods will become commonplace, and replace calculated variables. There are now glow plugs that measure cylinder pressure through the phases of crank angle, in OEM applications. I wish we had such things.

[DWR]

Originally Posted by _TB_

small update from me. I have been driving with a very light foot, and keeping a very steady speed all the time. this has helped, today I got the burnt rubber smell as it did the big regenerate program. error codes are gone and soot is down to 8g. pursue is now 8mbar at idle.

That's great news. Glad to hear of your success.

[_TB_]

Originally Posted by DWR

That's why the OEMs have not done what you have proposed.

They have - to some extend. All sensors are subject to plausiblity tests - to make sure their output does not drift or give values that are simply not plausible.

EDC16 has far more plausibility tests than EDC15

[DWR]

Originally Posted by _TB_

They have - to some extend. All sensors are subject to plausiblity tests - to make sure their output does not drift or give values that are simply not plausible.

EDC16 has far more plausibility tests than EDC15

Yes, that was my point. I was responding to this:

Originally Posted by UberArchetype

I'm still not warmed up to the idea that all these sensors and plausibility calculations always contribute to things working as expected, or not as the case may be. Why not a simple drive pressure/boost pressure differential with plausibility?

Not that what UberArchetype said is wrong. The DDE does both, plausibility of sensors AND plausibility of relationships. They are different and have different purposes. Relationship plausibilties cannot necessarily detect sensor inaccuracy.

[SoZoX]

At some point DPF pressure sensor goes I have replaced mine. Usually adaptive values for the sensor are at 0. I have not seen anything else on 4-5 cars I scanned. As someone else mentioned thermostat needs to reach 90+ c. and also there should be no glow plug related errors.

I drive 98 % of time on highway to work and back. Speeds around 90 all the time sometimes more. I have observed regens and it wont regen while you are driving like an maniac. I drove like this for a while and at some point it goes into mainac regen mode but it does not like it. The message read from ISTA was car was forced to regen in maniac mode(cannot remember the real code but was not ordinary regen) . I believe you need to take it easy sometimes for it to go into ordinary regen. I can sense it by now when it needs to go .

[Persian Whisperjet]

Originally Posted by SoZoX

I can sense it by now when it needs to go .

A man and his horse.

[POBEP]

Sorry for bumping old thread.
I still do not get "How does the ecu calculate the amount of soot in the DPF".

Here is my LONG regen(s) story.

2013 E70 X5d
All stock, minus swirl flaps, plus Provent 200.
Thermostat replaced recently, coolant temp 88C-ish within 7min of cold start.
MAP sensor failed 4 weeks ago (pulled one from 335d until replacement delivered)
All vacuum components still factory (will do it this summer).
Codes: none.

summer (service) season May..Oct:
Driving profile: 50/50 highway city
rare local trips at altitude of 6,400
often with small trailer.
approximate 1 week totals: 40mi

winter (primary) season Nov..Apr:
Driving profile >95% highway.
2x way trips of 3h/190mi, plus few local trips of 10..35mi
1 Week totals ~500mi

190mi profile consist of
- 120mi of fairly flat at sea level
- 70mi of elevation change to ~ 7,377ft (2,249 m)

Over last 3 years, I noticed that the interval between regens:
- at sea level could be as low as 60mi <- subject of concern
- above 4000ft are hovering at 300mi

I got bimmerlink app and has been watching soot mass values.
Regen kicks-in promptly when soot mass reaches ~43g .

The soot mass value
- grows fairly fast at sea level <- subject of concern
- drops to 0 within 10min of the regen cycle <- works as expected
- decreases (!) as altitude increases <- subject of concern

Yesterday soot dropped from 37g at sea level to 14g at 6,400ft.
This morning soot mass dropped below 10g as it climbed to 8,652ft.

So, back to $1M question: "How does the ecu calculate the amount of soot in the DPF"?

And, $1B question: why my DPF soot-ing rate is altitude-sensitive?

_TB_ DWR Nadir Point lnxguy

[who is this noob]

Originally Posted by POBEP

The soot mass value…
- decreases (!) as altitude increases <- subject of concern

Yesterday soot dropped from 37g at sea level to 14g at 6,400ft.
This morning soot mass dropped below 10g as it climbed to 8,652ft.

What are your EGTs?
Under constant load climbing a mountain…
Is it possible the DPF is getting hot enough to burn soot without a formal regen cycle?

[Tambohamilton]

Originally Posted by E85 Sport

What are your EGTs?
Under constant load climbing a mountain…
Is it possible the DPF is getting hot enough to burn soot without a formal regen cycle?

Passive regen is indeed a thing, so it could come down to driving habits at the different altitudes rather than the altitude itself.