FunfDreisig provided the text from the owner's manual, but here is some more info on the BMW diesel particulate filter. - It goes into a regenerative mode every 300 to 2000 km, automatically. The engine computer decides when to do the regen cycle based on how hot the vehicle is, how fast and how far you have driven it, etc.
- If it completes the cycle while you are driving it, you may never notice it (apart from the rough running and reduced power)
- When in regenerative mode, the engine management is altered to keep the revs up (like driving in DS). You may notice in manual mode that the vehicle won't go into 6th.
- Fuel management is altered, so the engine may be sensed to be running roughly during the regenerative cycle
- Regenerative mode provides additional restriction to intake air, so power can sometimes be sensed to be down slightly. Throttle response is also reduced, ie it can feel more sluggish
- The regenerative mode burns off the particulates trapped in the DPF. It does this at 600 C. No visible particulate emissions should be there, but the smell will be, as a residual effect of the process
- The smell is described as caramel, possibly slightly burnt. Heavy, sweet, not like raw fuel odour.
- E90 35d owners report that during the regenerative cycle, it is very easy to burn your fingers opening the hood due to the amount of heat retained. If you suspect the vehicle is in a regenerative cycle (which is normal, but perhaps you want to prove it to yourself), touch the airbox under the hood. It will be very hot to the touch. Not sure where the DPF is on the X5, it may be further back in the exhaust.
All part of the joy of BMW diesel ownership. Not sure I would call it a character stamp, perhaps more of an undocumented feature.
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2007 X3 3.0si, 6 MT, Premium, White
Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue
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