X5 35d "de-particle" process

[deutsch100]

How often does this departicle process take place? It seems to happen a lot while driving (which is better than in the garage after being parked...this process stinks), but when it occurs while driving, the car is noticeably "heavy, coarse and sluggish" feeling. It does pass generally quickly, but seems to be a frequent process!

[Diesel Guy]

It's called "regeneration"...... Passive regeneration occurs normally while driving if exhaust temps are high enough.....active regeneration occurs when temps are low, and as the back pressure in the catalyst rises, the system begins to regenerate.....and this is what you might smell when you pull in the garage .......I haven't sensed any performance issues, and I don't know if BMW is able to control either turbo to raise temps during regen which might be the performance issues you've sensed....

[boyce89976]

We've put 2k miles on our 2010 X5d and have not noticed this process at all, either while driving or while in the garage.

[deutsch100]

Originally Posted by Diesel Guy

It's called "regeneration"...... Passive regeneration occurs normally while driving if exhaust temps are high enough.....active regeneration occurs when temps are low, and as the back pressure in the catalyst rises, the system begins to regenerate.....and this is what you might smell when you pull in the garage .......I haven't sensed any performance issues, and I don't know if BMW is able to control either turbo to raise temps during regen which might be the performance issues you've sensed....

Thanks for the response. The manual in my '11 35d, actually calls it departicle process, but regeneration makes sense too! It mentions that during this brief process you might need to press the accelerator more, and notice a different feeling in the car while driving. Usually this "process" happened when I pull in the garage, but lately it's been happening when I am driving.

Funny, I imagined the majority of the "smell" would come from the exhaust pipes, but when this process happens while parked in the garage...the smell is strongest in the engine bay!

[Armand]

In over 15k miles I can't say that I have definitely spotted one much less felt sluggishness or other performance impact. I am sure it is happening but it manages to go unnoticed.

[deutsch100]

Originally Posted by Armand

In over 15k miles I can't say that I have definitely spotted one much less felt sluggishness or other performance impact. I am sure it is happening but it manages to go unnoticed.

Do you do more highway driving? My driving is at least 90-95% city driving, so there are many chances to notice this. I imagine on the highway or at a steady speed...it would be totally unnoticeable.

You've never had the funny smell when pulling in the garage, or parking? I get it quite often. Even called the dealer, and they said almost EVERY diesel owner calls about this "smell". It's even in the manual!

[Armand]

Originally Posted by deutsch100

Do you do more highway driving? My driving is at least 90-95% city driving, so there are many chances to notice this. I imagine on the highway or at a steady speed...it would be totally unnoticeable.

You've never had the funny smell when pulling in the garage, or parking? I get it quite often. Even called the dealer, and they said almost EVERY diesel owner calls about this "smell". It's even in the manual!

I believe I noticed the smell once on the street. I got out of the car and immediately noticed a sweet smell. I only drive it weekends on relatively longer drives. But never noticed a loss of power or anything unusual. My wife drives the rest of the week (mostly around town) and she has never complained about the smell. I wonder if fuel could influence the frequency of regeneration. Do you get winter diesel? I think winter diesel has higher particulate content and so I would expect the engine to regenerate more frequently. Also, I don't use unbranded diesel nor additives.

Edit: I noticed you live in Woodland Hills so no chance of winter diesel! Can't think of another reason ...

[Mosman]

I don't have a diesel, so I can't comment on what mine does, but I'm very familiar with the process.

There is a DPF (Diesel Particulate Filter) in the exhaust. It's usually in the muffler. The role of the DPF is to filter the black soot out of the exhaust Soot is created by unburned fuel which occurs mostly at low engine loads....like idling. So if you do a lot of idling, like city driving, you are going to produce a lot of soot which is going to collect in the DPF. When the backpressure gets high enough, the engine will change it's mapping to raise exhaust temps to burn the soot in the DPF and convert it to ash (in some cases, fuel may be injected into the DPF itself to burn it off, I'm not sure how BMW's system works).

If you are doing a lot of idling and city driving, you might be building up more soot, and requiring more frequent "regeneration" or burn-off of the soot in the DPF. If the engine gets put under a heavy load fairly frequently, that alone will keep the temps up and keep the DPF clean.

The urea tank is part of a catalytic process that reduces NOx emmisions. That's the other part of the Tier 4 emissions reduction.

[Mosman]

The smell may be the result of the exhaust system getting hot as it regenerates, which is why you are smelling it in the engine bay, not the out of the tail pipe. If the exhaust manifold is getting really hot, it might be burning off cosmoline, heating up the coating, etc. It'll be interesting to see if the smell goes away over time.

[JasonG]

I've noticed mine regen once in about 1700 miles....smells sweet...didnt notice while driving but when we pulled up to the house....