Passat Active Regens - How Often [Fans run after shutdown]
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darrelld
Veteran Member
I have noticed the same, when they do occur the duration is much shorter than my 2010 Jetta.
skinnyb
Veteran Member
I wonder if it has something to do with the urea? It requires less heat to activate a regen so it would make sense it takes less time.
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darrelld
Veteran Member
Urea allows the exhaust to run at a higher temp which creates more NOx but the Urea takes care of this. Soot is vaporized quicker at the higher exhaust temps. You will also notice the cold engine temps come up much faster in the Passat.
My Jetta is forced to use cooler exhaust temps with EGR to prevent the creation of NOx.
http://www.youtube.com/watch?v=bgusjGRP3XQ
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Ozzmosis86
Well-known member
I have noticed a few times where the fans have been running full blast after I parked the car and turned it off. They did this in pretty cool weather with relaxed driving. Is this a regen? If not, how can you tell a regen is occurring?
darrelld
Veteran Member
When the fans are running it means you interrupted a regen.
Regen's work similar to the trash can in your kitchen. Trash (soot) is collected filling to the point emptying (Regen) is needed. Your wife (DPF sensor) tells you (ECM) the trash is getting to the point it needs to go out. Now for some reason you start to empty the trash but you get interrupted. The trash can continues to fill until you get the chance to empty it. The amount of trash and how fast its collected can vary based on a variety of activities.
tdiatlast
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...and because the regen was in progress, it already generated excess heat, thus the fans are working at high speed. When you turn the engine off, the regen stops, but the fans have to keep running until the temps come down to a preset level.
On new cars, there will be some nasty odor for the first few regens...not from the exhaust, but, I believe, from the materials surrounding the DPF.
This is probably not necessary, but when time permits, I don't allow the regen to be interrupted...I'll continue to drive around my neighborhood, keeping my revs about 2k, to help blow out the soot.
On new cars, there will be some nasty odor for the first few regens...not from the exhaust, but, I believe, from the materials surrounding the DPF.
This is probably not necessary, but when time permits, I don't allow the regen to be interrupted...I'll continue to drive around my neighborhood, keeping my revs about 2k, to help blow out the soot.
darrelld
Veteran Member
You will notice the rpm needle hovering round 1000 while idling.
tdiatlast
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Also, if you're using a ScanGuage, which shows you real coolant temp, coolant temp rises from normal 198-202 to 206-210. At least, that's what mine shows...ditto for my 09 JSW.
MyAvocation
Top Post Dawg
LMAO! Okay Darrell, now describe the DEF system with a similar metaphor.
darrelld
Veteran Member
The downstream post DPF exhaust is like the water in your pool. In order to thoroughly clean the water (post DPF exhaust) you add chlorine (AdBlue or the generic equivalent).LMAO! Okay Darrell, now describe the DEF system with a similar metaphor.
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jbright
Veteran Member
Is the DPF on the Passat the same as the one on the 2010 -- 2012 Jetta/Golf? Also, does the Passat have an 'exhaust flap'?
Ozzmosis86
Well-known member
Haha, I understand what I regen is, I just wasn't sure how to tell if they were occurring or not. I have lots of experience with diesel engines, but not any in owning and operating them. All of my experience is the in the design and development of the engines.
suprnice
Member
I had an interrupted regen once after I parked and turned off the engine, fan under the hood running like crazy with loud noise, after a few minutes, didn't know what happened, I restarted the engine and the loud sound was gone, hopefully it didn't do much damage..
tdiatlast
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740GLE
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The downstream post DPF exhaust is like the water in your pool. In order to thoroughly clean the water (post DPF exhaust) you add chlorine (AdBlue or the generic equivalent).
wait, so you pee in the pool to make it clean?
TomB
Veteran Member
Well this analogy fails since Adblue is Urea which is what Urine breaks down into so you can't equate it to chlorine.wait, so you pee in the pool to make it clean?
Chlorine does nothing for the pee. The urea levels keep climbing, biological processes not Chlorine break it down. The Chlorine just kills and then the shocking level of Chlorine oxidize "burn up" the organic dead matter. Urine is actually sterile, it is what gets pickup on the way from the kidneys that is an issue. TMI.
darrelld
Veteran Member
The analogy was about treatment and conversion processes not the specific molecular or biological components of the process.Well this analogy fails since Adblue is Urea which is what Urine breaks down into so you can't equate it to chlorine.
Chlorine does nothing for the pee. The urea levels keep climbing, biological processes not Chlorine break it down. The Chlorine just kills and then the shocking level of Chlorine oxidize "burn up" the organic dead matter. Urine is actually sterile, it is what gets pickup on the way from the kidneys that is an issue. TMI.
Biz
Active member
Does the regen cycle create an odor? I smell a slight kind of thickly sweet engine odor at times. Seems worse now (16K miles) than when the car was new. I usually drive 40 miles at a time for my normal commute. Doesn't seem normal. My throat was burning on a long drive recently (all-day). Is it something I should have the dealer look at, or will it go away?
NSTDI
Veteran Member
Do you know what anti freeze smells like? Most people describe it as sickly-sweet.
Don
Don
tdiatlast
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Biz...are you smelling this inside your cabin? That could be coolant, not regen.
FYI, many with 09-10 CR TDIs, myself included, report smelling coolant at various times, and no one has been able to pinpoint a source. Yes, this engine is plumbed differently, I just thought I'd point this out.
I'm still surprised by the odor (OUTSIDE the cabin) of my 09 JSW (52k miles) regen, when I have to interrupt it, shutting of the engine while the fans continue to run. But, it's not sickly sweet at all...more like hot rubber/paint...
FYI, many with 09-10 CR TDIs, myself included, report smelling coolant at various times, and no one has been able to pinpoint a source. Yes, this engine is plumbed differently, I just thought I'd point this out.
I'm still surprised by the odor (OUTSIDE the cabin) of my 09 JSW (52k miles) regen, when I have to interrupt it, shutting of the engine while the fans continue to run. But, it's not sickly sweet at all...more like hot rubber/paint...
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Biz
Active member
Definitely not coolant, and not constantly, that's why I suspected the regen cycle, if it gives off an odor that can possibly make its way inside. Noticed nothing in the hour I was driving it this AM. I'll have it checked out next time it is in for service.
Pretty sure I had an active regen yesterday doing Blvd stop and go driving. My car normally shows about 780 rpms at idle, 6MT version. Yesterday, I noticed a stink while doing 40 mph, getting inside the dash, came up to a red light, stopped for it waiting, and my rpms were showing about 840-850 instead, but I didn't hear any fans going on, a big dump truck was idling next to me with my windows down, so it may have been there, maybe not. Light turned green, smell went away, next red light about a mile away, nothing, idle back to 780 rpm, no smell, no nothing. Makes me wonder how long it takes time wise to do a re gen, seemed I almost missed it completely. I need to get a newer VAG com cable that will do Hex Can.
In another note, ran my finger inside the tailpipe, only thing that showed up with the white glove test was dust, no soot, nothing black at all. Amazing, so far.
In another note, ran my finger inside the tailpipe, only thing that showed up with the white glove test was dust, no soot, nothing black at all. Amazing, so far.
TomB
Veteran Member
Encountered my first regen on Saturday. 2600 miles on the car.
I noticed that the car sounded differently when I stopped for a light. It had a louder roaring noise to it. It seem to have more clatter than usual as well.
Pulled into the gym and saw the RPMS above the normal 800 at about 900 after parking. Opened the hood, both radiator fans were running. The engine sounded like the valves were chattering. It was probably the injectors on the Common Rail working double time. And the exhaust system sounded like the metal was heating up. You know that metal contracting or expanding sound.
And yes the exhaust smelled unusual like a burnt plant matter smell.
I let it go for about 10 minutes but needed to get going so shut off the engine. It did not seem to restart again. It had been running about 10 minutes before I parked.
I noticed that the car sounded differently when I stopped for a light. It had a louder roaring noise to it. It seem to have more clatter than usual as well.
Pulled into the gym and saw the RPMS above the normal 800 at about 900 after parking. Opened the hood, both radiator fans were running. The engine sounded like the valves were chattering. It was probably the injectors on the Common Rail working double time. And the exhaust system sounded like the metal was heating up. You know that metal contracting or expanding sound.
And yes the exhaust smelled unusual like a burnt plant matter smell.
I let it go for about 10 minutes but needed to get going so shut off the engine. It did not seem to restart again. It had been running about 10 minutes before I parked.
How often do the regen cycles occur? I know it depends on driving habbits but on average, how often?
I have 400 miles on my new Passat. Got home, turned her off and the fans were running. I also smelled a little bit of the same smell when my Diesel truck regens. Not 100% the Passat was in regen mode but I'd bet it was. 400 miles seems very early for the first time and I would think it would regen every 800 miles or so ( once per tank). My truck will regen every 700 miles or so. The VW manual does not address this. Thanks!
I have 400 miles on my new Passat. Got home, turned her off and the fans were running. I also smelled a little bit of the same smell when my Diesel truck regens. Not 100% the Passat was in regen mode but I'd bet it was. 400 miles seems very early for the first time and I would think it would regen every 800 miles or so ( once per tank). My truck will regen every 700 miles or so. The VW manual does not address this. Thanks!
tdiatlast
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Previous 2.0 CR TDIs do an active regen every 300-400 miles, depending on how the car is driven. I would assume this 2.0l TDI is probably the same, so 400 miles seems about right. I just returned from a 2600 mile road trip, and never noticed a regen, so they must have occured while cruising.
TomB
Veteran Member
I have been paying CLOSE attention and I have not noticed anything to indicate them. Perhaps they are so short lived that you don't really notice it until you stop.
TheGrove
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This is the only time I notice mine.
I had one happen yesterday, I could tell when I stopped at a light and the rpm was up a bit(then parked where the fans kept running), I think that is only the 2nd one I have noticed since I've had the car now at 17,000 miles, sure there have been plenty more, but it sure seems like lots less than I used to notice on my 2011 Golf.