Passat Active Regens - How Often [Fans run after shutdown]

Niner said:

Do you get on the freeway or highway or interstate much, where a 70 mph blast for 10 or 15 minutes would allow a passive regen to occur? Is there much biodiesel in your fuel there in WA?

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I get about 10 minutes each way of my commute on the highway.

Yes, PLENTY of BD here. I have a 275 gallon tote in the garage because I still use the B100 in the two 2005 Passats.

I add one gallon per tank for lubricity.

Jason4 said:

I've decided that I'm going to replace my current B5 A4 in August, it'll be my birthday and I'll hit the 200,000 mile target around then. I'm not sure what I'll get to replace it, I've been doing a lot of hiking and climbing lately and there are a few trail heads that have pretty rough logging roads on the approach. Like I said a few posts ago a TDI Touareg would be perfect but my price range is more like $30K.

As for raising the idle when you notice it's in the middle of an active regen go back and read my earlier post (#32). I work with this stuff for a living and trust me when I tell you that you aren't helping things.

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Remote access is why I have the 07 Jeep GC Diesel. MB 3.0L V6 for towing snowmobiles in the winter and the Polaris Ranger in summer.

No different running it 2500 rpm or on the freeway at that rpm.

TomB said:

Remote access is why I have the 07 Jeep GC Diesel. MB 3.0L V6 for towing snowmobiles in the winter and the Polaris Ranger in summer.

No different running it 2500 rpm or on the freeway at that rpm.

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I've looked a bit for a diesel GC but they are pretty rare. How has your's been for reliability?

Are you saying that there is no difference running your VW parked in the driveway at 2500rpm vs running it on the freeway at 2500rpm? Those two conditions are very different.

Jason4 said:

I've looked a bit for a diesel GC but they are pretty rare. How has your's been for reliability?

Are you saying that there is no difference running your VW parked in the driveway at 2500rpm vs running it on the freeway at 2500rpm? Those two conditions are very different.

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GC has been great. Yes, very rare. A co-worker just found one a month ago and got it.

Since you are so in the know of the TDI, how much fuel can be injected post combustion for the DPF regen? Can more be injected at 2500 RPM versus 900 RPMS. That was my point.

TomB said:

No different running it 2500 rpm or on the freeway at that rpm.

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yes, there is. speed and load are two different parameters when considering engine operation...

you're not helping it by raising the engine speed while stationary, unless your goal is preventing the regen.

I'm not especially in the know with VW's TDI engine, the engines that I'm involved with are much larger but the basic principles are the same. The control systems and strategies might be totally different though. I bet VW is using Bosch and so it is probably similar to some of the other light truck diesels like the Duramax in terms of control strategies.

I suspect that you could inject more post combustion fuel at a higher engine speed but not substantially more. You have more combustion events per minute but your amount of time that you have to inject post combustion is much shorter for each event.

The two things that are needed for a regen to occur are heat and fresh air. VW probably runs with less EGR during a stationary regen, I'm not sure how they would operate if you overrule their stationary regen mode. They might also be doing some tricks during a stationary regen that they don't do if you overrule it. In the system that I'm familiar with you would be taking the system from what is considered to be an idle condition (with a modified idle set speed) into a running condition with a torque demand based on the accelerator pedal position.

Ours did a regen on the way to Impex today. EGT was just under 1200F for about 5 minutes and coolant temp went up to 210-212F. No difference at all in the way it felt from a driver's perspective.

VeeDubTDI said:

Ours did a regen on the way to Impex today. EGT was just under 1200F for about 5 minutes and coolant temp went up to 210-212F. No difference at all in the way it felt from a driver's perspective.

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Did you get a log of this going on, on VCDS? Graphs or charts? Good find there.

Nope. Just noticed the temps on the ScanGauge. Never would have known if it hadn't caught my eye... perfectly seamless.

I'm not sure how relevant this is to you guys, but I still want to throw this out there for you all.

I am very familiar with diesel pickups and the workings of their emissions systems, and one of the ways I can tell when my friend's 6.4L Powerstroke is in a regen is by listening to the exhaust sound. Everything else in the truck sounds about the same except if you listen to the exhaust with the windows rolled down and you get on the throttle a bit. It's not a throaty nor a turbo sound, but rather that jetwash turbulent sounding whooshing of really hot regen exhaust being mixed with relatively colder surrounding air.

The reason I bring this up is for you guys that are always wondering how to tell when your car is in a regen, and because I suspect you can hear similar sounds coming from your Passat when it's "doin' it's thing." That said, this is just a theory about the sound coming from these Passats, but I figure one of you guys could "pipe up" (sorry for the pun!) and tell us whether similar observations have been made with these Passats.

The Passat exhaust is almost inaudible. A friend of mine has a 6.4 and a 6.7 and I know what you're talking about - although neither of them has done a regen lately.

By the way, welcome aboard!

VeeDubTDI said:

The Passat exhaust is almost inaudible. A friend of mine has a 6.4 and a 6.7 and I know what you're talking about - although neither of them has done a regen lately.

By the way, welcome aboard!

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Thanks! I plan on joining this TDI crowd at some point in my relatively near future, but my plucky Volvo is doing well so all is good!
Oh, and yeah I know what you mean there. My buddy is getting sick of 12 MPG and wants me to help him make those regens stop for good one of these days!

Expect 18 - 20 MPG after you fix that problem. That's in an F-450 though...

VeeDubTDI said:

Expect 18 - 20 MPG after you fix that problem. That's in an F-450 though...

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He has a F-250 4x4 short bed CC. So there is a possibility for a bit more MPG than that, huh?
He says EGR gotta go aswell. I think that'll help the MPGs along some too.

Let's not go too far down that road since discussing those types of modifications is a bit taboo around here.

But I agree.

I see, I see! My bad guys!

I'm wayyy too used to the Cummins, Powerstroke, and Duramax forums where that subject basically has it's very own section, and just happens to be the most discussed section there! But, I digress...

Noticed another regen on the highway the other day. It seems that the target exhaust temperature is 1125°F. The car does an amazing job of maintaining that temperature (or very close to it) regardless of engine load.

VeeDubTDI said:

Noticed another regen on the highway the other day. It seems that the target exhaust temperature is 1125°F. The car does an amazing job of maintaining that temperature (or very close to it) regardless of engine load.

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VCDS or scan gauge II that it was noted on?

ScanGauge II. We don't drive around with a laptop hooked up.

VeeDubTDI said:

ScanGauge II. We don't drive around with a laptop hooked up.

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Oh come on, you two are peas in a pod... surely the VCDS will be hooked up in june on long trips to MI and everywhere else you'll be going this month. One drives, the other one logs data.


Speaking of which, when BMW is testing their fleet and comes out from Death Valley, CA at 300 below sea level to Sabrina Lake up highway 168 at almost 10,000 feet in the Sierra Nevada Mountains, there are 4 or 5 folks in every car... one driver, and 3 or 4 engineers, each with a laptop, logging every thing they can think of for test purposes. I have seen these test crews in 5 or 6 different modeled BMW's numerous years in a row when on fishing trips in the mountains at lake Sabrina. The engineers don't wear lab coats, BTW... usually shorts, with ghost white legs sticking out of them, no tan lines, with thick german accents and limited english.

How do you get the scangaugeII to give you exhaust temps? Thanks...

You have to set up an X-Gauge for Cat #1.

Niner said:

Oh come on, you two are peas in a pod... surely the VCDS will be hooked up in june on long trips to MI and everywhere else you'll be going this month. One drives, the other one logs data.

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We might be surfing the internet and chatting, but not logging data. BORING.

VeeDubTDI said:

We might be surfing the internet and chatting, but not logging data. BORING.

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Maybe figure out a way to piggyback the laptop on top of the scangauge II from the OBD II port and start logging when you see the exhaust temps get jacked up. That would be an accomplishment. an obd II powerstrip?

Pretty sure you can buy obd 2 splitters

FirstOrbit84 said:

Pretty sure you can buy obd 2 splitters

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You can, but the SGII has two ports, you can just plug into the unused port and get the data from there, they are "T" internal to the SGII.

IXLR8 said:

You can, but the SGII has two ports, you can just plug into the unused port and get the data from there, they are "T" internal to the SGII.

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Forgot about that, good find! But does it work with VCDS and the license in the dongle?

Niner said:

there are 4 or 5 folks in every car... one driver, and 3 or 4 engineers, each with a laptop, logging every thing they can think of for test purposes.

The engineers don't wear lab coats, BTW... usually shorts, with ghost white legs sticking out of them, no tan lines, with thick german accents and limited english.

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youre describing pretty much every vehicle calibrator on the planet haha
there are couple other places around the country that are popular hangouts for OEM testing, where vehicle engineers can be seen "in the wild"

For reference, this is how hot the gas coming out of the tail pipe is at idle when a regen is going on:



It smelled like boiling pasta.

-J

I was kind of worried about that furnace blast hitting my front tire on my mountain bike, it was right in line.