For those noticing there DPF is not regenerating, your thermostats are shot. The engine needs to be at it`s operating temp of 90c in order for the DPF regen to work. There`s two thermostats, the main one and the EGR thermostat.

 

tried it all, gave up, £500 lighter, but it is gone! Car is fine now.

 

Hi, what production date is your car? If it is a newer one you probably have the DPF and CAT in one can, this way it is not visible from under the car. The damn thing is located right after turbo. This kind of DPF does not produce any sound during its regeneration, the only way you can recognize that it's regenerating is checking your instant consumption.
Read all your posts and your worries about the glow plugs were right. If one of them is faulty, the regeneration will not start.

Conditions that need to be met:
- coolant temperature >75°C
- exhaust gas temperature > 240°C
- no faulty glow plug (most probably no errors stored in DDE memory at all)
- steady ride (ideally driving on a cruise control)
- not too much clogged DPF
~ [optional] it's always better to check the functionality of the temperature sensors as well (charged air sensor, two exhaust sensors)

If you had a problem either with thermostats or glow plugs, your car stopped to perform the regeneration and that led to clogged DPF.

I would suggest to check the error memory from time to time just to avoid such bad things from happening. Bad luck that BMW engineers did not implement some kind of DPF regeneration status indicator into the cluster...

 

Where did you get this ?
glow plug have nothing to do with regeneration. If it wouldn't generate with a faulty glow plug many would have problems with the DFP.
On mine 4 glow plug where dead but it regenerated fine.
Errors stored in de DDE if they arn't relevant to the regeneration won't have an effect either, would be stupid if it was.
Steady ride hasn't got anything to do with it either.

 

this is a generally known fact that the DPF regeneration will not start automatically when the glow plugs are faulty
also, if you'll be checking the regeneration status while driving you'll notice that when you try to accelerate the regeneration will stop for a moment until you return to a steady drive

 

It for sure isn't the case with our engines. Do you have any proof that it doesn't regenerate with a faulty glow plug ?
Its well know that the glow plug in our engines are fragile, in many cases you won't even notice one is faulty. In mine at least 4 where dead, the fifth one wasn't much better. Only 1 was OK. And still it started with -15°C . not very good but it did. In higher temperatures or with more still function I would have never found out, unless reading it out. Yet it still regenerated fine.
An engine not reaching operating temp will not regenerate that is very true but with faulty glow plug it DOES regenerate. So please give us proof.

How can you see it will stop when you accelerate ? Beside the noise and higher fuel consumption one doens't know its regenerating.
Don't believe this one bit, it regenerates by increasing the exhaust temp. This is a process you can't stop that quickly. yes the engine may run different when you accelerate but that doesn't mean it won't regenerate.
Ones the filter reaches +600°C the soot will burn off. Impos to stop this while accelerating. Also why would it do this ??

 

no real proof about the glow plugs
but for the second case, just hook up a computer with DIS and watch the regeneration status
there is no noise on the newer DPFs (the ones with CAT in one piece) so it's really hard to recognize when is the regeneration active unless you have a diag hooked up

 

Not familiar with DIS, did you hook it up when you where driving ?.
Looked it up in WDS which mentions :
So yeah you where right it works "best" when the speed is constant, which doens't mean it won't work when the speeds isn't constant just not as effective. Would it be because the temperature is difficult to control when then engine is accelerating ?
Nothing in there about the glow plugs though.

 

My ex-car did the regeneration just fine with one faulty glow plug.

- Antti -

 

are we talking about a requeted regeneration or automatic regeneration?

hmm, just read some threads about the glow plugs and some people say that it'd not start the regeneration if more than three of them are faulty
where's the true now

as higher exhaust temperatures are accomplished by post injection process, it is not possible for the electronics to predict the fuel amount if not driving steadily, therefore the regeneration is being paused when a significant change happens (driving with no gas applied, braking, significant acceleration required) and continues again during "more predictable" drive / constant speed