[roelofjan93]

Dear all,

I have a strange problem with my E91 330D from 2009 with a N57 engine. The DPF is continuously performing regens but they are never successful. Backpressures appear fine after replacing sensor. Exhaust temperature during regen seems low (around 480 degrees C). The engine is standard and tuned to 328HP at 200k km. Currently 300k km.

Some background info:

The previous owner had the DPF replaced (April 2023) for a refurbished DPF as the car did not pas MOT. They did not replace the pressure sensor back then.

When I bought the car in August 2023 the car had fault codes: 004C5E, 004D03, 00452A. (read out with Carly) The previous owner went with the car to the garage and they said the DPF was faulty and that they would replace it with another refurbished DPF under warranty. During regens the car would smoke (white/grey) which the previous owner confirmed started occurring after the first DPF filter change.
The new refurbished DPF has been mounted end of September and they have reset the DPF values etc.

At first everything seemed fine until I got a fault code 004185 while at high speed on the German highway two weeks later. Exhaust gas temperature before catalytic converter higher than 750 degrees C, which could be correct considering I was accelerating hard and at speeds above 200km/h. (Error occurred at 247km/h, see fault freeze data from Carly) I tried reading the sensor with Carly on the way back and it appeared to be dead as the reading was stuck at -0.044 degrees C. (I could also have read out a wrong sensor or non existent sensor as Carly is not always clear) However, when I later checked with ISTA I was reading the exhaust gas temperatures just fine.

Two days later the car started to smoke again and with Carly I saw that a regen was running and soot mass was at 55gr. However, soot mass did not go down while it continuously was doing regen. (only like 0.01gram per minute) Fault code I got was 00480A. Back home I used ISTA to run a backpressure test and I saw values in the range of:

Idle: -19hPa
2000RPM: -10hPa
Cut-off: 20hPa

So it appeared to be a faulty backpressure sensor.

What did I do so far:

While checking the backpressure sensor I also noticed the following:

- the charge pipes were leaking on all four seals so replaced them and also intake seal on the turbo
- CCV breather pipe was toast and leaking, so replaced it as well
- intake had quite some CBU, cleaned as much as I could behind the throttle valve (will do extensive CBU cleanup later)
- charge pipes and intercooler were oily, same as charge intake temperature sensor, but as I read this is quite common/normal? I cleaned all of them
- CCV breather pipe was also oily and air intake before turbo
- I replaced the backpressure sensor and checked the rubber hose but this was clear
- checked the exhaust pressure sensor pipe in the manifold but this one was also clean
- checked the turbo shaft play and could not feel any major play

After all this I did a backpressure test and the values appeared normal/clean.

Idle: around 6hPa
2000RPM: around 30hPa
Cut-Off: around 60-70hPa

However, during test driving it was again performing a regen while backpressure was around 35hPa on the highway at around 120km/h in 6th gear. Today I drove again for 20 minutes at highway speed and it was again regenerating without success. Carly said soot mass 45gr this morning when I left and when back home still the same value.

Somehow the car keeps regenerating without success.

What I found so far:

- White/grey smoke during regens seems not normal/only happening when exhaust temperature is not high enough
- Exhaust temperature seems low at regens (only 480 degrees C)
- Coolant temp is nicely 90 degrees C
- Backpressure sensor was probably faulty
- EGR test was okay, set point was reached a bit slower than 0.5 seconds
- Fuel usage is continuously higher during regens (+-1L/100km I think)

Tomorrow I will do the following:
- Replace temperature sensor in DPF (maybe it is faulty after all)
- Reset all adaptations
- Reset DPF
- Perform air mass system test
- Perform intake sooting test
- Perform injector test
- Check EGR value during driving

I called a local BMW specialist in the Netherlands today and they could also not figure out what the problem could be or in which direction I have to look. Somehow, the car thinks the regens are not successful and keeps requesting them.

I hope someone can point me in the right direction as it is currently searching for a needle in a haystack.

Thanks!

Best regards,
Roelof Jan

[Andystobbs]

Does your car have an exhaust pressure sensor at turbo outlet?

[roelofjan93]

There is one pressure sensor on the exhaust manifold (pre turbo) and one on the DPF. See attached picture and figure from Realoem.

[roelofjan93]

The sensor you mean is I think this one in de figure from Realoem. That one I don't have and is also greyed out in Realoem.

[Andystobbs]

That DPF looks rough, even for after market. I think I'd feel compelled to take that off and inspect it.

Is it possible DPF was deleted previously with the remap? Do you know the previous owner?

[roelofjan93]

I agree that it looks rough. It looks like it has been cut open just before the exhaust pressure pipe and rewelded again. Also the second temperature sensor point (which I believe is on the N57 335D models) has been grinded down and welded shut. They painted it with some zinc spray or something which comes off if you touch it with your hands.

This is the supplier of the refurbished DPF:
https://www.offenga.nl/bmw-onderdele...roetfilter-n57

Their picture looks a lot cleaner and not rewelded in the middle. I can try to look with my probe camera into the DPF from the exhaust end or perhaps through the lambda sensor hole before having to remove it.

I tried to remove the temperature sensor today but the garage damaged the nut with a normal spanner instead of using an open ring spanner. So I will have to try to grind the nut back in shape....

I know the previous owner and the DPF should still work. If it was coded out I would think that it also does not try to regen anymore!?