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Originally Posted by gryffishhawk
Very helpful information FaRKle! Yes, the fan does come on now from time-to-time when I shut down the engine and always wondered what that fan was trying to do. Anyway, TY! and I hope to run some of these ideas by my service center next time I’m in. I’m surprised they never mentioned the nuances of the regen process and effects on the engine. And yes, you’ve described my experience perfectly--so, a handful of times I’ve parked the car and when i got out I could hear a fan running and thinking ‘wonder what that’s about' so, this sounds like I may have turned off the engine during a regen? I’ve had the car some five plus years now and can probably count on one hand the number of times this has happened. Can’t recall it ever happening in the first couple of years but it happens sometimes now.
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It won't always turn on the fan if you shut down the car during a regen, only if it's hot enough. In colder weather I haven't noticed the fan come on when shutting down during a regen, but in the summer it frequently happens.
Quote:
Originally Posted by gryffishhawk
Also, would you know if BMW’s N47 engine bases the regen on mileage (perform a regen periodically whether it’s needed or not) or does it actually measure the pressure differential on either side of the DPF to determine when the DPF is clogged and needs cleaning? Does it inject diesel directly into the DPF to clean it (bypass the engine) or does it add the diesel as part of the exhaust stroke from the engine?
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I believe the car will automatically regen after a certain amount of miles (400ish?) in addition to the DPF measurement. I don't recall where the extra fuel injection is. There was a BMW diesel engine tech document (I believe on the fest forums) that explained the system in detail.
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Originally Posted by eugene89us
Here is a YouTube link to the sound the engine makes when this "surging" experience happens. The tach is usually very stable or variation that is not noticeable. But you can hear that surging sound and you can feel surging vibration in the steering wheel also. And goes away immediately upon putting the car out of drive. Can you post your videos?
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When mine did it, it seemed the same as yours.