Techy DPF info

[Llanigraham]

I'm still trying to understand why you need this info?

[Ryeman]

It only interests me in that I might learn how to avoid longer term DPF issues and extend its life cos I'm a tightarse :-)))

[muddyboots]

I'm still trying to understand why you need this info?

 

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).

 

 

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

 

 

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.

[muddyboots]

Oh, and: 

 

I doubt many will be interested in this level of detail...

[weasley]

Sorry, but you're wrong.  I am FASCINATED by this level of detail!  I work in an industry very much linked to DPF life and find this really interesting (and totally understand your "because I can" reasoning for doing it!).

 

As a scientist I also love a good chart and like to analyse and dissect it.  One thing I noticed is the apparent difference in resolution between EGT sensor 3 and 4 - is this a charting anomaly (ie line-smoothing on one trace but not the other) or are the data really this different?  Is the logging frequency the same on both?

 

Keep up the good work. 

[Nick P]

It looks like EGT 3 and 4 are the same sampling frequency. With 4 sitting further back in the exhaust away from the manifold, I'd expect the chart to be smoother.

[muddyboots]

One thing I noticed is the apparent difference in resolution between EGT sensor 3 and 4 - is this a charting anomaly (ie line-smoothing on one trace but not the other) or are the data really this different?  Is the logging frequency the same on both?

 

Keep up the good work. 

 

 

That's actual data, no smoothing, and the logging frequency is the same on both.

 

There are actually 4 measuring blocks for EGT in VCDS, but the first two don't seem to give any sensible values so I guess they're not used on a CR170 Yeti.

3 and 4 both showed sensible data, both warming up as expected when I first start up, block 3 warming up more quickly.

So I think it's fair to assume block 3 measures temps going into the DPF (which is effectively EGT as it leaves the engine, as the DPF is mounted so closely to it) and block 4 measures temps on the DPF outlet.

Block 4 will presumably always lag block 3 due to the mass of the DPF honeycomb in between.

If there are times when Block 3 is cooler, I wonder if this is on over-run, when cooler air is passing more or less straight through the engine, and cooling the DPF inlet.

 

Remember that last graph I posted is over a fairly long period of time, probably around an hour and a quarter.

Haven't got the data to hand to check, but I think data is logged every 1-2 secs; am logging 12 blocks simultaneously in VCDS "turbo" mode. 

[muddyboots]

Thing I'm keen to understand is the meaning of "measured soot" and "calculated soot".

The "calculated" value seems to rise fairly steadily, whereas the "measured" rises more slowly and fluctuates a lot more.

 

Wonder if the guys at RossTech know....

[thingy]

I see,       well not quite.

Anyway, very interesting. Thanks to muddyboots for an intriguing post. 

Part that I find strange is; Loc. 338  the Ks since last regen of 100770m. That seems a long long way. Still maybe my maths is wrong, again.

Good luck to you and keep up showing us the info.

[muddyboots]

I see,       well not quite.

Anyway, very interesting. Thanks to muddyboots for an intriguing post. 

Part that I find strange is; Loc. 338  the Ks since last regen of 100770m. That seems a long long way. Still maybe my maths is wrong, again.

Good luck to you and keep up showing us the info.

Think the units are wrong in VCDS for that block, should be metres not kilometres

[muddyboots]

Found this interesting page on the RossTech site:

http://wiki.ross-tech.com/wiki/index.php/Diesel_Particle_Filter_Emergency_Regeneration

 

Remember it's CR engines in the Yeti, so skip past the stuff for the PD engines.

[weasley]

Aaah, I assumed 3 and 4 referred to cylinder numbers. That explains that.

There will be a lot of algorithm-based data based on some sensor data and plenty of interpretation and extrapolation. I am told that OEMs would replace all sensors with algorithms if they could (including things like coolant temperature and even fuel level) as software is cheaper than hardware (and easier to install, share, change and update). I would guess that they use cross-DPF pressure delta to make assumptions about soot (and ash) loading, as well as data from the engine map to determine how the engine has been running (and therefore what amount of soot would be expected).

[Ryeman]

Did I get this right....there are two soot values?

Would it be that one is total, pre DPF and the other is post DPF and the closing of the values triggers regen?

Just a thought, or am I simply showing my ignorance again?

[Balfy]

Great info Muddyboats.

 

We also have a CR170 2.0 which had some DPF concerns after a few good years of motoring and it once went into a limp-home mode. 

 

One of the main reasons we ended up buying the VCDS was to help clear codes and perform diagnostics without a dealership or local garage charging for the cost of performing the analysis.

 

I must admit I've not attempted to monitor a forced re-gen with VCDS connected but next time the EMU light comes on I will give it a go using http://wiki.ross-tech.com/wiki/index.php/Diesel_Particle_Filter_Emergency_Regeneration#1.6l.2F2.0l_R4_CR-TDI

 

Since the first limp-home issue we have completely stopped using supermarket fuel.

 

On occasions when the EMU light stays on longer than usual and I know it is the DPF I add some fuel additive to help matters and usually within the next driving cycle it clears.

 

I get the fuel additive from Costco at a good price and anything that can save me the cost of a DPF replacement is worthwhile doing.

[DonjSZ5]

The joys of going back to petrol.

 

But this said we have used super market fuel in ALL our cars, 13 covering approximately 800,000 miles with no power loss problems.

 

Only 1 of our cars, a diesel Vitara, ever went into limp mode and it was due to an air pipe popping off the turbo.

[weasley]

The joys of going back to petrol.

Direct injection petrols make more small particulates than diesels, meaning that future emissions regulations may well mandate GPFs.

Edited 29 May, 2014 by weasley

[DonjSZ5]

bring them on

[Ryeman]

To me, the story of second grade fuel from supermarkets, is more a case of successful marketing of/by 'Brand Power' ads on TV.

We need a 'deep throat' leak from within IMO.

[Llanigraham]

To me, the story of second grade fuel from supermarkets, is more a case of successful marketing of/by 'Brand Power' ads on TV.

We need a 'deep throat' leak from within IMO.

 

That might be the case in Australia, but over here it is well known that although the base fuel may be the same the supermarkets do not include all the same additives in their fuel. Typically that includes not having any or having a much less amount of system cleaners, and with diesel no anti-foaming agent.

[Ryeman]

Our 'cheap' diesel doesn't foam.

[BossFox]

Muddyboots, does this mean you are no longer planning to stage 2 your car and remove the DPF if you are spending this amount of time looking into the cycles?

 

My 170CR Yeti is now a bit over two years old, with 33,000 miles on it.

In that time I've only actually noticed a regen cycle about three times.

[Ryeman]

With a 5yr warranty, I'm too scared to have the ECU upgraded.

[Balfy]

The joys of going back to petrol.

 

But this said we have used super market fuel in ALL our cars, 13 covering approximately 800,000 miles with no power loss problems.

 

Only 1 of our cars, a diesel Vitara, ever went into limp mode and it was due to an air pipe popping off the turbo.

 

Perhaps we have just been unlucky and the problem may not have been down to fuel issues - it's a component that could have other issues causing the concern.

 

Our last two diesel cars have both had issues with DPF. Both are used on regular mixed journeys - very few short journeys I hasten to add. Regular services, etc.

 

Speaking with a local experienced garage mechanic about the issues, the first question he asked was where we bought fuel from and he suggested we look to buy elsewhere using a brand.

 

I'm not saying the problem has gone away, but we have not had a subsequent "limp home" issue since moving away from supermarket fuel. It's a personal decision and one I'm comfortable with.

 

Given we've done away with supermarket onsite shopping and saved more by not driving to the shops (and ending up buying more than we need) it's a win-win for us personally. 

 

Perhaps I need to do some more work with VCDS to get more insight into the DPF issues.

[Balfy]

Muddyboots, does this mean you are no longer planning to stage 2 your car and remove the DPF if you are spending this amount of time looking into the cycles?

 

My 170CR Yeti is now a bit over two years old, with 33,000 miles on it.

In that time I've only actually noticed a regen cycle about three times.

 

With the new legislation are people still looking at ways to "adapt" or "bypass" the DPF?

 

Again just a personal choice - I had looked at it previously, but given the new tests it is a risk that the car may fail the MOT and for that reason I've decided to take the option to keep the DPF - hopefully it keeps doing regens and clearing out successfully.

[skomaz]

With the new legislation are people still looking at ways to "adapt" or "bypass" the DPF?

 

Again just a personal choice - I had looked at it previously, but given the new tests it is a risk that the car may fail the MOT and for that reason I've decided to take the option to keep the DPF - hopefully it keeps doing regens and clearing out successfully.

 

It's a risk yes - but I've yet to hear of a vehicle failing under the new tests where a DPF has been removed...