Techy DPF info

[muddyboots]

I doubt many will be interested in this level of detail, but I've found a copy of the VW Self Study guide on the "catalytic coated diesel particulate filter" (aka...the DPF).

 

See here:  http://www.volkspage.net/technik/ssp/ssp/SSP_336.pdf

 

UPDATE: The above link refers to older design DPFs. NickP provided this link to the self study guide of the 2.0L CR TDI engine:

http://www.natef.org/NATEF/media/NATEFMedia/VW%20Files/2-0-TDI-SSP.pdf

The DPF system is detailed from page 56 onwards.

 

For anyone wanting to know more about how their DPF works, it's a good read.

 

I was also poking around in VCDS at lunchtime, looking at what measuring blocks are available in the engine module, that relate to the DPF operation.

I've attached (hopefully) a screenshot of the ones I was looking at.

 

I remember driving home from work last night and thinking the engine sounded more gruff than usual, and wondered if it was a regen.

Looking at the time/distance values since last regen in VCDS, looks like it was.

 

I'm keen to understand how often, and why, I am getting active regens, so will probably log a few journey's worth of data in VCDS, along with EGT (exhaust gas temp). Be interesting to see how my typical driving pattern relates to EGTs and the need for active regens. 

Maybe there's a happy medium between driving gently enough to get reasonable MPG (but requires more active regens which uses more fuel, as EGTs are too low for passive) - and driving slightly harder so that EGTs remain high enough to regen passively and not require extra fuel to regen (but use slightly more fuel anyway).

 

Anyway, keeps my mind occupied while I'm driving at least, thought it might be interesting to some of my fellow geeks out there

[weasley]

That's really interesting. I'd love to know the inputs to the algorithm that is predicting soot and ash volumes.

[muddyboots]

Logged well over an hours worth of data tonight, over 40-odd miles. Right mix of roads, starting with urban crawl, followed by giving it some beans, and then some steady A-road cruising. Logged the measuring blocks in the earlier image I posted, plus EGTs and boost pressure.

 

WIll be interesting to see if & how the soot mass changed over the drive, just need to get the data imported.

 

Hoping to log again tomorrow morning and evening, hoping to catch it doing a regen!

 

Note I don't have any specific problems, just doing it out of geeky interest.

[Ryeman]

Thanks for that, extremely interesting.

I hate been treated as simply a consumer and treated like a mushroom in not being expected to know what exactly what is going on.

I've been running up to the CBD recently with the instant consumption indication showing strange jumps in consumption when on the flat from ~4.5 to 6+ for no apparent reason which I put down to regen as the only reasonable explanation.

I'd love to know at what speed the best compromise is achieved.

I am happy to cruise at 90 kph (GPS) but don't know if it's fast enough for natural regen.

I've noticed that at ~70kph in 6th you get sub 4L/100 but is this false economy?

How much fuel is consumed with each regen for instance?

Look forward to more.

[Nick P]

Probably worth noting that doc is from when they were about to launch the PD170 engine in 2005. The high level principals are mostly applicable to you though, but of course anything about unit injectors and cam profiles isn't relevant to a Yeti. Sensor numbering is also different.

[Nick P]

The training guide for CR 2.0: http://www.natef.org/NATEF/media/NATEFMedia/VW%20Files/2-0-TDI-SSP.pdf - this is the US version so I think the DPF portion should be the same as your car but there may be additional elements to the emissions control too.

 

See pages 56 onward for description of DPF and how regen works etc.

[muddyboots]

The training guide for CR 2.0: http://www.natef.org/NATEF/media/NATEFMedia/VW%20Files/2-0-TDI-SSP.pdf - this is the US version so I think the DPF portion should be the same as your car but there may be additional elements to the emissions control too.

 

See pages 56 onward for description of DPF and how regen works etc.

Great stuff, thanks.

[muddyboots]

... this is the US version so I think the DPF portion should be the same as your car but there may be additional elements to the emissions control too.

I notice in that guide, there are 3 different catalytic converters; one sat on top of the DPF, and two others separately downstream.

 

Any idea if the CR170 Yeti has all of those ?

[muddyboots]

Been logging a bit of data - see the attached graph.

 

If the guides are right, and passive regeneration occurs when EGTs are in the 350-500ºC range, then it seems that despite having a 40-odd miles commute, I'm not hitting that temp range for sustained periods.

I guess this is a result of rural A-road driving where there is frequent lifting off, and also speed is limited in many places to 40-50mph (by speed limits and/or other traffic).

Also note that the couple of spikes where the temps exceeded 500ºC were because of deliberate attempts to see how high they would go, IE putting the engine under maximum load for a period of time. These circumstances will very rarely arise as I don't intend to repeat that style of driving very often...

 

Not sure what the difference is between the two soot values. 

 

I'm hoping to log a few more journeys, and hopefully catch an active regen in action. 

 

 

 

[kenfowler3966]

My car is approaching 60k miles and is due to be replaced with a new Yeti in 5 weeks.

 

I do a fair amount of motorway driving and can honestly say I have never noticed a regeneration or any change suggesting one is taking place.

 

Presumably my mix of driving makes it unnecessary, eg 270 miles yesterday, mostly at 60mph+, and I repeat this trip every month for work

[muddyboots]

I should mention this again - not doing this because I think there's an issue, just wanting to understand more about what really goes on.

 

Presumably my mix of driving makes it unnecessary, eg 270 miles yesterday, mostly at 60mph+, and I repeat this trip every month for work

 

Judging by what I've logged, I think if I did sustained cruising at those speeds I'd just be heading into the temp range where passive regens occur.

 

But this data is from a CR170, it may vary for other engines. The engine in a 110 TDI would be revving higher at similar speeds, which might help get the EGTs up.

[Ryeman]

So if I cruise at 90/56 for 40+ mins it's not enough stress to trigger regen?

[muddyboots]

So if I cruise at 90/56 for 40+ mins it's not enough stress to trigger regen?

 

Well some things to remember:

 - this data is from a CR170, other engines may differ. Ambient temps may well differ too and have some effect.

 - my driving is not a steady cruise

 - the temp range of 350-500ºC is where passive regeneration takes place, without any intervention from the ECU - it's just happens naturally due to the catalytic coating in the DPF.

 - if passive regen doesn't take place, then an active regeneration will take place periodically when the soot levels reach some set level, where the ECU injects more fuel for some time to raise the exhaust temps and burn it off. You may not even notice this is happening.

 

So driving with EGTs in the 350-500ºC region doesn't trigger a regeneration as such, it just happens naturally in that temp range (which is good as it doesn't use more fuel).

[Ryeman]

Muddyboots thanks for that.

Wish I had an EGT gauge cos I don't know if my style is 'hot' enough.

[muddyboots]

It's all measured using VCDS...(formerly known as vag-com).

If you have a laptop, you can buy the VCDS cable and a whole world of geekery awaits

[Ryeman]

It's all measured using VCDS...(formerly known as vag-com).

If you have a laptop, you can buy the VCDS cable and a whole world of geekery awaits

Oh dear!

Sorry, but is it just a cable......what does it connect to? (My ignorance of techy stuff)

[Wardy]

VCDS diagnostics cable connects to the car at one end (OBD port) and a USB connector at the other end, that connects to a laptop.

[muddyboots]

Oh dear!

Sorry, but is it just a cable......what does it connect to? (My ignorance of techy stuff)

You'd probably do well to have a poke round the VCDS forum on here ( http://www.briskoda.net/forums/forum/23-diagnostics-vcds/ ).

Also have a look at the RossTech site to what VCDS can do ( http://www.ross-tech.com/vag-com/ ).

 

But in short, VCDS is a WIndows program that eseentially gives you all the diagnostic / configuration capabilities of a main dealer.

It works on all VAG vehicles (VW, Audi, Seat, Skoda).

It connects to the "OBD2" diagnostic port on your car, on a UK Yeti it's tucked away out of sight under the RH dash.

To connect requires a special type of cable between the diagnostic port, and your computer. A laptop is obviously easier to work with!

 

VCDS isn't free; you can download it, but it requires a license.

if you buy a genuine RossTech cable, that will act as a license "dongle", which enables the software to work.

 

There are other cheaper cables, and no doubt knock-off copies of the software.

But given how valuable a tool it is, and how useful it's been to me over the last few years, I preferred to go the legit route and support the makers in the future development!

[Ryeman]

Is it Yeti specific?

[muddyboots]

Is it Yeti specific?

No, it works on all VAG group cars.

 

It also provides generic OBD functionality, so will read fault codes etc on a lot of other cars too.

[g6zru]

You'd probably do well to have a poke round the VCDS forum on here ( http://www.briskoda.net/forums/forum/23-diagnostics-vcds/ ).

Also have a look at the RossTech site to what VCDS can do ( http://www.ross-tech.com/vag-com/ ).

 

But in short, VCDS is a WIndows program that eseentially gives you all the diagnostic / configuration capabilities of a main dealer.

It works on all VAG vehicles (VW, Audi, Seat, Skoda).

It connects to the "OBD2" diagnostic port on your car, on a UK Yeti it's tucked away out of sight under the RH dash.

To connect requires a special type of cable between the diagnostic port, and your computer. A laptop is obviously easier to work with!

 

VCDS isn't free; you can download it, but it requires a license.

if you buy a genuine RossTech cable, that will act as a license "dongle", which enables the software to work.

 

There are other cheaper cables, and no doubt knock-off copies of the software.

But given how valuable a tool it is, and how useful it's been to me over the last few years, I preferred to go the legit route and support the makers in the future development!

 

 

 

 

I'd take issue with you about this part;"But in short, VCDS is a WIndows program that eseentially gives you all the diagnostic / configuration capabilities of a main dealer."

As far as I am aware VCDS is much more capable than the Dealers version and does many more things that they can't do!

 

Fred

[Ryeman]

Wow!

More than the dealer?

[muddyboots]

OK, exciting stuff, I've captured an active regen...

 

See attached image.

 

Pretty obvious when it happens, as the EGTs shoot up to around 600ºC.

Lasted for approximately 8 minutes.

 

It's been 287 miles since the previous active regen, which - if this pattern continues - it'll be almost 2 active regens per tank, or to put it another way, between 1 and 2 active regens per week for me.

[Ryeman]

Wow! 8 mins.

[muddyboots]

Wow! 8 mins.

 

Bear in mind I was driving probably around 50-60mph for most of that time, so a reasonable amount of exhaust gas flowing through the DPF.

I'm guessing if the regen happened while I was in urban stop/start traffic, it would have taken longer.