# So can you tell when regen is pending?



## F32Fleet (Jul 14, 2010)

It has been 3.5 yrs and over the last couple of months I can finally tell with some regularity when the car is due for / beginning DPF burn off. Sure enough when I get out of the car the fan is whirring away and I can feel the extra heat along with the caramel smell.

NE1 else pick up on the signs?


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## 335dFan (Nov 8, 2012)

BMWTurboDzl said:


> It has been 3.5 yrs and over the last couple of months I can finally tell with some regularity when the car is due for / beginning DPF burn off. Sure enough when I get out of the car the fan is whirring away and I can feel the extra heat along with the caramel smell.
> 
> NE1 else pick up on the signs?


I have noticed those same symptoms sometimes in my garage upon arriving. More fan-like noise, much extra heat, but did not pick up on smell.


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## F32Fleet (Jul 14, 2010)

I will say the smell has subsided over the years. It's faint now.


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## Hoooper (Jun 17, 2013)

any idea how often a regen happens? Roughly? I have only noticed the regen happening once, when I got off the freeway and it was clearly still trying to complete the cycle. Other than that, if it has been happening I dont know about it. I drive a lot of highway though and probably 15 miles each way every day is a highway through foothills so maybe its constantly getting a partial "regen" from higher EGTs while climbing a hill


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## BB_cuda (Nov 8, 2011)

BMWTurboDzl said:


> It has been 3.5 yrs and over the last couple of months I can finally tell with some regularity when the car is due for / beginning DPF burn off. Sure enough when I get out of the car the fan is whirring away and I can feel the extra heat along with the caramel smell.
> 
> NE1 else pick up on the signs?


Do you only pick up the caramel smell after parking? Do you ever know the regen is happening before coming to a stop? TDI_wise has all sorts of tech data he has pulled on this but we all know he isn't the average Joe.

On another thread, I was concerned about not hearing my engine fan running. This was when we were having a pretty hot streak in South Texas and I was running A/C almost non stop. So, this meant that fan was always running when i was driving. So, as the thread stated, I was never hearing the fan run after shutdown parking in the garage.

Lately, Texas has been experiencing monsoon so I haven't been running AC much. Sure enough, I often am hearing the engine fan come on after parking. Several responders to the thread felt that the engine fan would run after shutdown only if it was in a regen when i parked.


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## 335dFan (Nov 8, 2012)

BB_cuda said:


> Do you only pick up the caramel smell after parking? Do you ever know the regen is happening before coming to a stop? TDI_wise has all sorts of tech data he has pulled on this but we all know he isn't the average Joe.
> 
> On another thread, I was concerned about not hearing my engine fan running. This was when we were having a pretty hot streak in South Texas and I was running A/C almost non stop. So, this meant that fan was always running when i was driving. So, as the thread stated, I was never hearing the fan run after shutdown parking in the garage.
> 
> Lately, Texas has been experiencing monsoon so I haven't been running AC much. Sure enough, I often am hearing the engine fan come on after parking. Several responders to the thread felt that the engine fan would run after shutdown only if it was in a regen when i parked.


It has been rather hot here in MD the last couple of days. But I have been running no A/C. But there has been no fan running after shutdown in the last couple of days.

Sometimes, the car seems to be slightly sluggish and be running just slightly rougher, and I have thought that may be when the regen is occurring. What I have not clearly been able to correlate is that symptom with the in garage symptoms of fan noise and extra heat.


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## F32Fleet (Jul 14, 2010)

BB_cuda said:


> Do you only pick up the caramel smell after parking? Do you ever know the regen is happening before coming to a stop? TDI_wise has all sorts of tech data he has pulled on this but we all know he isn't the average Joe.
> 
> On another thread, I was concerned about not hearing my engine fan running. This was when we were having a pretty hot streak in South Texas and I was running A/C almost non stop. So, this meant that fan was always running when i was driving. So, as the thread stated, I was never hearing the fan run after shutdown parking in the garage.
> 
> Lately, Texas has been experiencing monsoon so I haven't been running AC much. Sure enough, I often am hearing the engine fan come on after parking. Several responders to the thread felt that the engine fan would run after shutdown only if it was in a regen when i parked.


When I first bought the car I could smell it in the cabin if I cracked a Window (release of pressure would pull the smell through gaps in the firewall. Now I don't smell it unless I get out of the car but it's very faint now.


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## txagbmw (Apr 15, 2013)

On mine notices a hot plastic smell. Most said on here said was the Reg system. Had it about
4 month. 600 miles. Its does it just about every time run to the store in back. Probably doesn't
go far enough to complete. Was going to mention to the dealer but forgot about it. Seems to
be running fine so let it do its thing.


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## BB_cuda (Nov 8, 2011)

Curious, does txag stand for Texas Aggie?


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## sirbikes (Aug 17, 2012)

Easy to tell on X5d ... While driving on hwy, instantaneous mpg drops significantly - if normally around 30, it will drop to 20 for 15-20min. If you get off hwy and driving around town, you may notice transmission holding gear longer before upshifting, keeping engine revs higher. If the cycle does not finish when you get home and turn off engine, you will hear the dpf and heat shields really pinging as they start to cool off. If you put your cheek above the hood where it meets the windshield, you will feel more heat than normal and smell a slight burning smell. 

I record whenever my car goes into regen mode so I can figure out based on my driving style and level of tune I am running, how often I can expect it to occur. Also, if there is a trend to more frequent regens I will know that the filter is becoming less effective and that gives me time to start looking for a replacement or deletion.


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## jfxogara (Oct 26, 2012)

Second what sirbikes said -- mileage drops way off. I tend to run my tank pretty empty and I think the car may be smart enough not to start a regen when you are low on fuel, but have noticed a couple of times that it does it right after I fill up.


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## Philm35 (Aug 19, 2010)

In nearly three years of ownership, I've NEVER noticed any evidence of my car going into regen. No heat. No smell. No smoke. No evidence of smoke on the rear bumper. How can I verify that the car is doing it at all?

--Phil


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## 335dFan (Nov 8, 2012)

Philm35 said:


> In nearly three years of ownership, I've NEVER noticed any evidence of my car going into regen. No heat. No smell. No smoke. No evidence of smoke on the rear bumper. How can I verify that the car is doing it at all?
> 
> --Phil


I thought I heard someone report one time that they thought a regen typically happened roughly every 400 miles. My aging brain cells may be remembering incorrectly. I would bet that "in general" you would be least likely to notice it if you were doing highway driving when it occurred. I know when I took my recent 2,000 mile trip I didn't notice anything. So maybe if you have a long commute you may never notice it. I notice mine sometimes when it doesn't finish when I arrive home and park her in the garage. And another time I remember sensing it on the way to work on my short 12 mile commute mixed roads.


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## F32Fleet (Jul 14, 2010)

Philm35 said:


> In nearly three years of ownership, I've NEVER noticed any evidence of my car going into regen. No heat. No smell. No smoke. No evidence of smoke on the rear bumper. How can I verify that the car is doing it at all?
> 
> --Phil


If it weren't then it would be clogged (think potato in the tail pipe) and you would know it.


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## Axel61 (Mar 10, 2011)

damn this tells me Im running my car to damn hard!!! LOL


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## TDIwyse (Sep 17, 2010)

Philm35 said:


> How can I verify that the car is doing it at all?
> 
> --Phil


~$15 bluetooth OBDII dongle from eBay or Amazon + $5 for Torque Pro (you can also use the free version) will eliminate all doubts.

EGT's go extremely high during regens and the EGR goes to near 0 utilization. When not in regen the normal EGR behavior is extremely high (although I normally take advantage of a "back door" in the software I stumbled on that turns the EGR completely off).

On my normal driving cycle (~15 ml trips to/from work) the car does a regen every ~400 miles. On long highway drives it has stretched to near 500 miles, but I've never had it go beyond that mileage. It appears to be primarly triggered by time of operation and number of starts for my utilization. I can monitor the DPF pressure with the Bavarian Technic tool and do not see any correlation with pressure and regen frequency.


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## BB_cuda (Nov 8, 2011)

@TDI, the EGR number in the 2nd frame. What does the 94.9% mean? 94.9% of time it is open to some degree. Another dumb one on EGR operation. Does the valve open to differing amounts or when it's open, is it full open vs partial open? The back door that you mention, is that the Torque Pro software? I haven't googled any of this yet. I figure your answers will educate many others besides me. thanks


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## TDIwyse (Sep 17, 2010)

BB_cuda said:


> @TDI, the EGR number in the 2nd frame. What does the 94.9% mean? 94.9% of time it is open to some degree. Another dumb one on EGR operation. Does the valve open to differing amounts or when it's open, is it full open vs partial open? The back door that you mention, is that the Torque Pro software? I haven't googled any of this yet. I figure your answers will educate many others besides me. thanks


I believe the EGR and Throttle % reveal their relative position. If they are at 0% then they are as closed as they can get, and at 100% they are as fully open as they can get. This is based on examing the data in different operating conditions (full fueling conditions put the EGR at ~0 and the Throttle at ~100% for example). The amount of exhaust gas being recirculated back to the intake would depend on the EGR valve position, the throttle position, the amount of boost/rpm etc. The reason the EGR is basically off during regen is the burning soot in the DPF needs an oxygen rich environment to burn/oxidize.

The "back door" (http://en.wikipedia.org/wiki/Backdoor_(computing)) has to do with the particulars of the setup I'm running, and unfortunately I need all of them to "enter" it, which involve some specialized custom things I'm doing. I posted some data on this over here if you're interested (posts 59/60): http://www.bimmerfest.com/forums/showthread.php?p=7679949


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