[Snick01]

Sorry for my first post being an internet diagnosis request...

I will try keep this to bullet points as it will be a wall of text otherwise.

The car:
2011 E91 330D Manual LCI, N57.
EGR blanked/programmed out, swirl flaps removed. DPF still in place. Car is remapped. Was fine for 6 months after map (just for reference).

Symptoms:

• No check engine light, no DPF light.

• Seems to take an extra rotation or two to start (might just be the colder weather?).

• Horrible fumes on cold start.

• rough idle at all times, cabin vibrations due to this.

• hunting idle when warm (and sometimes straight from cold), between 600 and 1krpm (roughly).

• hesitation at around 2k.

• intermittent power loss. tends to be after car is warm and I have been at a stop in traffic. Car feels flat and about half the power, like no boost. Comes back usually after I have come to a stop again.

• Struggle to maintain constant speed at 70mph on motorway, feels like its cutting back power then reapplying it.

• inconsistent low down power, sometimes power comes in smoothly, sometimes like a switch at 2krpm

• Diesel in oil - it is now coming up as overfilled again not long after another oil change.

• Fluctuating average MPG - currently a terrible 26mpg mixed driving.

So far I have tried/replaced:

• Replaced all glow plugs and controller due to fault codes with two.

• Replaced pre DPF pressure sensor due to fault code, and cleaned the tube out that links to it.

• Injector test - came back OK.

• Checked for boost leaks - came back OK.

• Checked around injectors in case of failed injector seal - very clean and dry around them all.

I initially thought DPF strangling the engine, but part of me now thinks HPFP seal. I have read that these can start to leak diesel through the seal and into the sump - can anyone confirm if this can happen because I seem to get really conflicting info on this, and most info on knackered HPFPs are about them catastrophically failing.
Another more common suggestion is that it is constantly failing regen due to clogged DPF, but would this also cause all of the other symptoms? And also surely a clogged DPF would light up my dash?

ANY help would be massively appreciated, or if anyone has any contacts to disappear my car because I am seriously fed up with it (/s)

Cheers.

[lnxguy]

If your DPF isn't handling regens properly all that extra fuel can definitely make it's way into the sump. Also why is the DPF still in place if you're tuned? The entire point is to get rid of that stupid thing.

[Snick01]

The DPF is still in place to make MOT time easier, when it was mapped there were no problems with it so it stayed. I got the car mapped for a bit more power

How do I know if it's not handling regens properly, and for what reason would that be? If it was due to an overly clogged DPF surely I would have a pressure differential error across the DPF of some sort?

[lnxguy]

Have you checked your thermostat? That's one reason why it wouldn't be doing regens properly. If it's not up to temp and attempts a regen, all that fuel ends up in the sump.