[armanos]

Originally Posted by zxwreg

Found this post by Yozh: https://www.e90post.com/forums/showp...24&postcount=4, from which I have a few questions:

is "DPF Differential Pressure Sensor" measuring STAT_ABGASDRUCK_VOR_PARTIKELFILTER_1_WERT (Exhaust pressure before DPF)?

is "Exhaust Pressure Sensor" measuring STAT_Exh_pTrbnUs_full_WERT (Exhaust Manifold Pressure = EMP)?

If that's right, and since both give similar pressure readings, I would assume the issue is not a bad sensor (unlikely both fail at the same time suddenly), and the pressure reading is real. Does that lead us to a clogged DPF?

I am aware of only the pre-dpf pressure sensors on these older diesels, never heard of an exhaust manifold pressure sensor on these.

So maybe they just calculate STAT_Exh_pTrbnUs_full_WERT.

Anyway, both correlate quite well. You have a severe exhaust restriction.

If the sensor is ok. But why would it fail? Could check that too.

EDIT: It appears that M57N2 engine (TOP or twin-turbo version) does indeed have a manifold pressure sensor, which connects via a steel tube and a banjo bolt to the exhaust manifold right at the turbine inlet. This sensor mostly appears on the N-diesels (TOP or twin-turbo versions of N57, but also 4-cyl N47N).

This is the sensor that is monitored with STAT_Exh_pTrbnUs_full_WERT parameter on TestO data logger.

This is separate from the pre-dpf pressure sensor, which connects via a hose to a tube coming off of the top of the dpf.

[armanos]

Originally Posted by zxwreg

Note: before starting engine, the red curve reads with ~990 flat and the cyan curve reads ~1010 flat, even though the red curve plots above the cyan curve (probably a bug in TestO PlayBack module). The video shows everything.

Seems I am reading ABSOLUTE pressure instead of diff above ambient pressure like you were getting.

So the DDE shuts off injectors because the exhaust pressure is measured too high?

Yes you are right, both sensors (as well as MAP sensor) read ABSOLUTE pressure in mbar (=hPa), and when engine is off it has to be about atmospheric pressure.

It appears so, that it cuts off the injectors, otherwise you'd blow off the exhaust. It is strange there are no codes though.

[zxwreg]

Noticed that pre-DPF pressure is higher than the exhaust manifold pressure, so seems it also points to DPF blockage besides the soot mass reading (2.64 oz).

Guess it's DPF delete time finally and hope issue will be gone after that.

Delete is the only way to keep the car long term

Originally Posted by zxwreg

STAT_Exh_pTrbnUs_full_WERT (Exhaust Manifold Pressure = EMP)
maybe it's unique to M57, see here: https://6post.com/forums/showpost.ph...3&postcount=13

which has similar reading to STAT_ABGASDRUCK_VOR_PARTIKELFILTER_1_WERT (Exhaust pressure before DPF).

Refer screenshot and video (https://www.dropbox.com/scl/fi/nvfgd...f7hua7szl&dl=0)

Note: before starting engine, the red curve reads with ~990 flat and the cyan curve reads ~1010 flat, even though the red curve plots above the cyan curve (probably a bug in TestO PlayBack module). The video shows everything.

Seems I am reading ABSOLUTE pressure instead of diff above ambient pressure like you were getting.

So the DDE shuts off injectors because the exhaust pressure is measured too high?

[armanos]

DPFs can be cleaned. Delete would require a DDE remap.

Personally, I'd have it cleaned. But then occasional monitoring of pre-dpf pressure is needed to avoid this kind of situation repeating.

[zxwreg]

Yea, clean is an option, but it is such a pain to work the dpf so I probably pay for some one to do the work, then can’t image the labor cost to take it out, clean then put it back…

[armanos]

I feel your pain, because of the twin turbos it's basically an engine-out job lol