Strange regen anomaly- Have you experienced a really long regen?

DerekG

Veteran Member
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Sep 8, 2013
Location
Oklahoma
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'13 4dr Golf TDI 6-speed manual
Just wanted to report an out of the ordinary experience simply for the sake of curiosity.

*First off the car ran perfectly the entire time. I didn't experience any loss in performance, strange noise, dash lights...etc. Just a really long regen.


On my way home from work the other day my car started a regen and I did like I always do and drove past my house and headed for the highway to let it finish. I have a scanguage II so I've always been able to notice regens right away and keep driving until they are complete, even if it makes me late for work or class lol

Every regen I've experienced up until this point has been 8-10 mins long regardless of whether it is city driving or highway driving. This time it lasted 25+ minutes and ~19 miles of driving in mixed city/highway. The scangauge read 1100-1400F Pre-turbo EGT and 1100-1200F DPF for the entire regen which in my experience is perfectly normal.

After 20 minutes I was starting to get concerned just because it has never had regen last that long. I disconnected the scangauge and then re-connnected just to see if it was a glitch, but it was still reading regen temps. What was also interesting was that while idling for a few minutes the aux fan didn't come on like it would normally do during a regen while sitting in traffic. Also note that the aux fan did come on during the first 10 mins or so of this regen like normal.

At about the 30 min mark I decided to turn off the car for a few seconds and then restart it just to see if this "soft reset" would help. After that the temps went back to normal and I went home.


My initial thought is that there was possibly a glitch in the scangauge that was making it read high even when the regen was over. That might explain why the aux fan wasn't coming on 25 minutes into the "regen".

Just looking for thoughts from you guys and if anyone else has experienced a similar thing. It hasn't had another regen yet since that was only ~70 miles ago, but I'll be sure and report back if the next one does the same thing.

Thanks!
 
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VeeDubTDI

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It isn't a glitch in the ScanGauge. I've had a long regen, but that was steady-state cruising on the highway. When I canceled cruise control, the regen stopped.
 

DerekG

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Oklahoma
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'13 4dr Golf TDI 6-speed manual
Alright cool, I won't worry about it then. I'm at 26,7xx miles now and the car is fantastic.
 

Cogen Man

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Jun 4, 2011
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Kingston, Ontario, Canada
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2011 Golf TDI DSG.
Had one long regen in my 2011 Golf. Lasted about 25 minutes. If you noticed your coolant temp on your SGII was also up during the regen that's a good verification that the SGII is working fine.
 

DerekG

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Location
Oklahoma
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'13 4dr Golf TDI 6-speed manual
yeah, it was running 200-204 the whole regen. Usually runs 191-198.
 

hotpocketdeath

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Mar 18, 2010
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Suwanee, GA
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2010 Golf TDI
I just had a long regen the other day. Ended up driving around another 10+ miles to make sure it finished and I could park the car.
 

Kenn JSW

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Sep 2, 2012
Location
SE WA State
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2013 Jetta Sportwagen
On my way home from work the other day my car started a regen and I did like I always do and drove past my house and headed for the highway to let it finish.
I think a lot of us have done basically this, myself included. My thought on this is that it's very anti-economy, anti-TDI, anti-green, or whatever you'd like to call it. Also a necessary (?) waste of time. The economics of a TDI in most places are already questionable due to the large difference in the price of diesel vs. gasoline. (Almost a dollar per gallon more for diesel where I live). Doing this makes it worse.

So we burn extra fuel just driving around to let the car finish its regen thing. (And the car is already burning extra fuel during a regen). Part of the problem, at least in my case, is that the car seems to pick the absolute dumbest times possible to start a regen. I drive for a hour, and then one mile from my destination the regen starts. Every time! It sure would be nice to have some interaction with the computer. "Would this be a good time to start a regen?" Yes/No. Then it could be put off for a bit until it made sense. (If delated too much, one would be forced). Some owners could handle that (like most on this forum), and others couldn't deal with it, of course, so it would need to be an enabled feature. Won't happen of course, but it's what I'd like to see.
 

schultp

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Michigan
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2010 Jetta Sportwagen, 6sp manual
On this site it has become a standard for many that they must continue to drive until a regen is complete. In reality, I have never seen any data posted here, or elsewhere showing that this is a required behavior.

For me, on occasion I interrupt a regen when I arrive at home or work and I don't think twice about it.

Drive more, worry less.

Paul.
 

hotpocketdeath

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Joined
Mar 18, 2010
Location
Suwanee, GA
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2010 Golf TDI
On this site it has become a standard for many that they must continue to drive until a regen is complete. In reality, I have never seen any data posted here, or elsewhere showing that this is a required behavior.

For me, on occasion I interrupt a regen when I arrive at home or work and I don't think twice about it.

Drive more, worry less.

Paul.
IMO, this is more common sense. If you are aware that oil can cook in your turbo, why on earth would you ignore it and continue on as if it couldn't happen?

Look up what Turbo Coking is and you will see that the number one way to prevent it is to let the turbo cool down before shutting off the engine. This is a very real condition and can cause turbo failure.
 

meerschm

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Fairfax county VA
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2009 Jetta wagon DSG 08/08 205k buyback 1/8/18; replaced with 2017 Golf Wagon 4mo 1.8l CXBB
Keep in mind that the increase in temperature of the DPF is not because the exhaust is hotter, it is because the exhaust has extra fuel injected late in the cycle, which is then oxidized in the converter just prior to the DPF.

the fan that runs allows air to pass around the Converter/dpf to carry off some of this heat.

650 c is kind of warm.
 

hotpocketdeath

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Joined
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Location
Suwanee, GA
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2010 Golf TDI
Keep in mind that the increase in temperature of the DPF is not because the exhaust is hotter, it is because the exhaust has extra fuel injected late in the cycle, which is then oxidized in the converter just prior to the DPF.

the fan that runs allows air to pass around the Converter/dpf to carry off some of this heat.

650 c is kind of warm.
Actually, the exhaust pre-turbo is much hotter during regen. I keep an eye on exhaust temps 1 and 3. 1 is the temps before turbo and 3 is pretty much the DPF itself. During regen, it's normal to see the exhaust temps before the turbo stay much higher than during typical driving.

Personal preference, I like to make sure the exhaust temps are below 600F before shutting down the engine.
 

DerekG

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Location
Oklahoma
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'13 4dr Golf TDI 6-speed manual
I too would like to see some kind of regen "countdown" meter so I can plan accordingly. Also I don't see driving until it's finished as wasteful at all, apart from wasting 10 mins. It's going to do the regen eventually and I'm definitely NOT going to turn off the engine when the Pre-turbo EGT's are 1200+ degrees fahrenheit.

I usually let both 1 and 3 EGT temps go down under 475-500 before shutting off the car.

It's just part of owning a newer TDI. Yes it's inconvenient at times, but it's not something that would make me want to get rid of the car.

For me, fuel economy was secondary when buying the car. For years I loved the idea of a Golf TDI and how versatile it was. The ability to tow, build quality, handling, subtle styling, and the pure utility is what made me like the car. Good fuel econ was a great bonus.

I'm not someone that even thinks about the price of fuel, it's going to cost what it costs and there isn't anything we can do about it so it's pointless to stress about the few cents that separate the cost a gas vs diesel.

I bought a diesel golf because I wanted a diesel golf lol
 

VeeDubTDI

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Springfield, VA
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‘18 Tesla Model 3D+, ‘14 Cadillac ELR, ‘13 Fiat 500e
On this site it has become a standard for many that they must continue to drive until a regen is complete. In reality, I have never seen any data posted here, or elsewhere showing that this is a required behavior.

For me, on occasion I interrupt a regen when I arrive at home or work and I don't think twice about it.

Drive more, worry less.

Paul.
This has been discussed extensively. There is no scientific data to back up one method over the other because nobody has bothered to sit down with a sample of vehicles and interrupted regens for 100,000 miles and compared failure data to vehicles that have not had regens interrupted for 100,000 miles.

Common knowledge of oil coking temperatures and general mechanical sympathy would say that it is not good to turn off a turbocharged engine when the turbocharger is 1300°F. It is the equivalent of pulling a heavy load up a mountain and turning off the engine as soon as you reach the top.

If you or anyone else wants to interrupt regens for convenience, then have at it, but it shouldn't be advocated as a safe practice, especially when one of the main goals of this site is to maximize engine longevity.
 
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IndigoBlueWagon

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I started a drive to New York a few months ago and as soon as I got on the freeway the car went into regen. Stayed there for 30 miles at 75 MPH. Didn't have the cruise set. I was pretty surprised, but all seemed well after.
 

OsirisTDI

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May 30, 2007
Location
Middle TN
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Tech Package DSG Golf, Executive Egg
Just wanted to report an out of the ordinary experience simply for the sake of curiosity.

*First off the car ran perfectly the entire time. I didn't experience any loss in performance, strange noise, dash lights...etc. Just a really long... it lasted 25+ minutes and ~19 miles of driving in mixed city/highway. The scangauge read 1100-1400F Pre-turbo EGT and 1100-1200F DPF for the entire regen which in my experience is perfectly normal.

After 20 minutes I was starting to get concerned just because it has never had regen last that long. I disconnected the scangauge and then re-connnected just to see if it was a glitch...

Thanks!
This was a regen of the NOX storage unit.
 

OsirisTDI

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Middle TN
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Tech Package DSG Golf, Executive Egg
It was a regeneration of the diesel particulate filter. The NOx cat regenerates very rapidly, as seen below.

Go for a ride on a highway. Bring someone with your VCDS. Initiate a DPF regen while driving, observe. After the DPF regen, initiate a NOX regen while driving, observe.

What you see during the VCDS initiated NOX regen while driving is very close to the OP's observation with Scanguage.
 

VeeDubTDI

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Springfield, VA
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‘18 Tesla Model 3D+, ‘14 Cadillac ELR, ‘13 Fiat 500e
If a NOx regen involved 30 minutes of elevated exhaust temperatures, I would think I'd be noticing them more frequently, based on the frequency shown in the graph above. :confused:

From my short period of driving a new Beetle TDI, the NOx regens involve very short periods of elevated exhaust temperature. I could be way off base though... I haven't tried initiating either of them in VCDS to see what happens.
 

OsirisTDI

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Tech Package DSG Golf, Executive Egg
If a NOx regen involved 30 minutes of elevated exhaust temperatures, I would think I'd be noticing them more frequently, based on the frequency shown in the graph above... I haven't tried initiating either of them in VCDS to see what happens.
Yeah, give it a try... It was bizarre.
 

VeeDubTDI

Wanderluster, Traveler, TDIClub Enthusiast
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Springfield, VA
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Newbie question: how do you know a regen has started? And how frequently do they typically occur?
Elevated exhaust temperatures. The dead give-away is when the DPF temperature is over 950F. They typically happen every 200 - 400 miles and last about 10 minutes.
 

hotpocketdeath

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Mar 18, 2010
Location
Suwanee, GA
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2010 Golf TDI
Newbie question: how do you know a regen has started? And how frequently do they typically occur?
I use the Torque app and monitor exhaust temps. There are 4 temperature sensors and the 3rd one is essentially the DPF. Whenever it spikes up above 900 or so, like VeeDubTDI mentioned, it's in regen.

There's also some other signs as well. Usually during regen, the engine idles a little higher and not as smooth as it normally would.
 

vwexpress

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Oct 27, 2019
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Davenport FL
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2015 Golf Sport Wagon
So if I'm new to modern VW's and haven't been able to notice the regen cycle, and I go to turn of the car while regen is occurring, what happens to tell me I'm turning it off at regen. And it I turn it right back on to let it finnish??
These gauges you guys are seeing the temps on, price, difficult in install?
 

prsa01

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mpls,mn usa
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14 jsw 6m, 96 B4v, miss my a4 :(
So if I'm new to modern VW's and haven't been able to notice the regen cycle, and I go to turn of the car while regen is occurring, what happens to tell me I'm turning it off at regen. And it I turn it right back on to let it finnish??
These gauges you guys are seeing the temps on, price, difficult in install?
2014 jsw 6m - the things I notice that tell me I'm in regen (most to least noticable) :
- fans running full blast at idle
- slightly elevated idle speed (maybe 50 - 100rpm)
- warm(er) air from vents in stop/go just venting outside air
- less power from stop, more likely to kill engine if not paying attention
- don't overly notice if at highway speed
After shutting down engine, fans will run full blast if during regen for a bit. Not sure about immediately restarting but others have stated interrupted regen will resume relatively quickly on next start.
 

03GolfTDI

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May 4, 2003
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Atlanta, GA
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'12 JSW DSG and '11 JSW DSG
2014 jsw 6m - the things I notice that tell me I'm in regen (most to least noticable) :
- fans running full blast at idle
- slightly elevated idle speed (maybe 50 - 100rpm)
- warm(er) air from vents in stop/go just venting outside air
- less power from stop, more likely to kill engine if not paying attention
- don't overly notice if at highway speed
After shutting down engine, fans will run full blast if during regen for a bit. Not sure about immediately restarting but others have stated interrupted regen will resume relatively quickly on next start.
^This - I typically notice the fans running full tilt first then glance down and see the increased idle (just under 1k RPM). The fans are quite loud when running at 100% and at least my car are noticeable with windows up and while sitting still.

I have interrupted a few regens over my 7 months of ownership, the fans will stay on after you shut down the car. When it was quick stop (convenience store, grocery store, etc.) the car immediately started regeneration as soon as I started back up. I have interrupted a regeneration twice on my way to work and my car sat and cooled for ~9 hours, both cases the regeneration started back up before I could get out of the parking garage (maybe 3-4 minutes idling down 6 levels).

Bolded above - I have DSG and my off the line response is MUCH better when in regeneration, wish it drove like that all the time and not just regeneration mode. :D
 

meerschm

Top Post Dawg
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Location
Fairfax county VA
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2009 Jetta wagon DSG 08/08 205k buyback 1/8/18; replaced with 2017 Golf Wagon 4mo 1.8l CXBB
So if I'm new to modern VW's and haven't been able to notice the regen cycle, and I go to turn of the car while regen is occurring, what happens to tell me I'm turning it off at regen. And it I turn it right back on to let it finnish??
These gauges you guys are seeing the temps on, price, difficult in install?

Most of the devices just plug into the OBD connector. some come with displays, some will display on a smart phone

You can also get an auto-polar device that displays on the VW instrument display. cost is $300 plus.




on the original subject, set your google on "Self Study Program 826803"


look around page 71 or so



there is a pretty good section on the various regenerations that dance around each other, including the longer elevated temperature cycle.


the long one targets sulphur, happens right after a DPF soot processing cycle, and can go for 20 minutes or so.
 
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-:vw:-

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Oct 7, 2019
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Somewhere, USA
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2014 SportWagen
On topic:

I've had some lengthy regens. I've not noticed any adverse effects from them i.e. overheating.

Off topic/tangent:

If mine feels like pulling that regen crap when I'm a block away from work or the house I park it and go on about my day (into work or home for the evening).

I don't let an inadamant object determine my schedule or cost me money in fuel driving around in circles.

Nothing personal but I think some in this forum are a bit too tight with things.

Just my .02.

Sent from my SM-G955U using Tapatalk
 
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JD_2012GolfTDI

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Location
Cameron Park, CA
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2012 Golf
I also use the higher RPM at stoplights as a sign that a regen is happening.

When I notice a regen is underway I now tend to shift into S or manual shift in order to maintain rpms in the 2K-2.5K range and assist with the exhaust temps a bit for the regen to complete. Keeping it in D allows the vehicle to lug an low rpms, and decrease exhaust temps quicker. Seems like I have less regens interrupted now when I turn off vehicle.
 

roadlust

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On topic:

I've had some lengthy regens. I've not noticed any adverse effects from them i.e. overheating.

Off topic/tangent:

If mine feels like pulling that regen crap when I'm a block away from work or the house I park it and go on about my day (into work or home for the evening).

I don't let an inadamant object determine my schedule or cost me money in fuel driving around in circles.

Nothing personal but I think some in this forum are a bit too tight with things.

Just my .02.

Sent from my SM-G955U using Tapatalk

Doing that is hard on the turbo and the exhaust system because of the high temperatures.


My .02 is thankfully we are all different. ;=)
 
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