So in theory when the required temperatures are reached then the regen is continuous until loads/speeds/temps reduce?

 

Seems odd when I have read many comments/complaints in this forum over the years about regens starting just when they get home after a long (speedy?) journey.

I was under impression it was as follows:

Passive regen: Normal cruising driving conditions the ecu does its thing with extra fuel to raise the exhaust gas temps enough to burn off the soot.

Active regen: driving conditions not enough to raise the temps to regen levels so ecu adds revs, fuel and cooling to force the dpf into regen.

 

Either way it requires extra fuel to raise the exhaust gas temps.

6 hours ago, Scot5 said:

 

This is typical of the replies to expect. Not for a second saying that's incorrect and if other garages solve the problem great.

 

BUT

 

Everytime I pass a Morrisons, the fuel forecourt is full of cars. Now if their fuel was crap and kept throwing up issues, their forecourts would be empty.

 

Conclusion:  It might be your car that's the problem?

So how come the ONLY time this CEL appeared was when I filled at Morrisons - not before and not since???

 

That seems pretty much cause and effect to me...

 

Of course you are perfectly at liberty to disagree

56 minutes ago, Gerrycan said:

So in theory when the required temperatures are reached then the regen is continuous until loads/speeds/temps reduce?

 

Seems odd when I have read many comments/complaints in this forum over the years about regens starting just when they get home after a long (speedy?) journey.

 

I don't know, I can only report my DPF is sitting pretty

I'll continue to buy diesel from any supermarket or fuel station which ever is the cheapest. Have had no problems in the past. 

Can i be dumb and ask what the heck this regen malarkey is all about?

From what i can tell noone really knows whats better. I put in morrisons fuel when im low and passing but will put in a little then get esso later. Know guys who work at the refinery at Grangemouth and say theres little difference as all tankers fill up from same pipes then its what the companies put in or dont that makes the difference and even then they are quite secretive about it. One mate has always used Bp ultimate fuel and has never had bother with his cars so dunno if that says anything.

3 hours ago, MarkyG82 said:

I was under impression it was as follows:

Passive regen: Normal cruising driving conditions the ecu does its thing with extra fuel to raise the exhaust gas temps enough to burn off the soot.

Active regen: driving conditions not enough to raise the temps to regen levels so ecu adds revs, fuel and cooling to force the dpf into regen.

 

Either way it requires extra fuel to raise the exhaust gas temps.

 

No, a passive regen, as already stated, is when the load conditions are as such that the exhaust gasses heat up the DPF enough to turn the soot into ash. There is no input from the car at all. Personally, I am of the opinion that cruising on the motorway does not get the DPF anywhere near hot enough to do any passive regenerating but I would happily change my view if somebody showed me some evidence.

 

The only time extra fuel is added during the exhaust stroke is when the car is doing an ACTIVE regeneration.

3 hours ago, tunedude said:

 

I don't know, I can only report my DPF is sitting pretty

 

If your car is tuned, as your username and signature both suggest, then it won't behave the same as one in factory calibration.

 

I think for standard cars all regens are probably active, but some will be much more noticeable than others.

 

I vaguely remember reading stuff on tdiclub  a few years back about people watching for rich spikes in the oxygen sensor readings to know when their cars were regenning; that suggests active intervention and increased fuelling.

Edited 21 June, 20196 yr by Wino

10 hours ago, Russ77 said:

 

The best think I did was to buy a £12 bluetooth ODB2 dongle and £3.30 for he VAG DPF app, you can see exactly what the car's doing in terms of DPF regens

 

Any particular dongle? In the market for one you see for this very purpose.

 

53 minutes ago, Wino said:

 

If your car is tuned, as your username and signature both suggest, then it won't behave the same as one in factory calibration.

 

I think for standard cars all regens are probably active, but some will be much more noticeable than others.

 

I vaguely remember reading stuff on tdiclub  a few years back about people watching for rich spikes in the oxygen sensor readings to know when their cars were regenning; that suggests active intervention and increased fuelling.

 

I wouldn't say most regens on a bog standard car would be all active if you're doing the  mileage to get the exhaust system up to temperature. Active regens were added to the DPF system because manufacturers became aware of them getting blocked potentially too quick if drivers didnt get them up to temperature. It's a bit of a back up feature so to speak.

Edited 21 June, 20196 yr by tunedude

1 hour ago, courty said:

 

Any particular dongle? In the market for one you see for this very purpose.

 

This one https://www.amazon.co.uk/gp/product/B01AC7I7BO/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1 😀

Sometimes I think ignorance is bliss. Just let it do what its be designed to do.

It's a built in feature of which you have little or no control over.

 

 

1 hour ago, ords said:

Sometimes I think ignorance is bliss. Just let it do what its be designed to do.

It's a built in feature of which you have little or no control over.

If your driving profile suits the DPF regen requirements then I agree there is no problem.

But for those people who don't have the requisite profile/mileage then ignorance could be less than bliss.

 

I also disagree that the driver has little control over the process, especially when a cheap dongle and app can give ample warning that a longer drive, or letting the engine tickover for 5 minutes, might be a good idea

Edited 22 June, 20196 yr by Gerrycan

I was always told that should only buy a diesel with DPF if every 10th run is at least 45 minutes.  Nice simply rule.

 

An engineer friend explained that active regen won’t start until fully warmed after starting, which takes 20-25 minutes (nearer 30 minutes on cold winter day), then takes 15-20 minutes.

Then said don’t want to be going too fast as airflow will cool the exhaust system making it take longer, he joked it would be fastest in uphill crawling traffic jam. 

 

3 hours ago, SurreyJohn said:

I was always told that should only buy a diesel with DPF if every 10th run is at least 45 minutes.  Nice simply rule.

 

An engineer friend explained that active regen won’t start until fully warmed after starting, which takes 20-25 minutes (nearer 30 minutes on cold winter day), then takes 15-20 minutes.

Then said don’t want to be going too fast as airflow will cool the exhaust system making it take longer, he joked it would be fastest in uphill crawling traffic jam. 

 

I've had a regen begin within 3 miles/5 mins of leaving work, the coolant wasn't even up to temperature.  Surprised me tbh!

This AA link outlines the DPF rather well..........

 

https://www.theaa.com/driving-advice/fuels-environment/diesel-particulate-filters

On 21/06/2019 at 10:00, Scot5 said:

Can tell you right now, the only direct answer to your question will be biased opinions from armchair speculators - nobody will be able to tell you the actual reason.

 

What I'd be more concerned about is when you say there are more regenerations per tankful.  How many re-generations do you typically experience per tankful? If the car is going thru regeneration quite often then that suggests the fuel isn't your problem. Are you driving EXACTLY the same each week?

 

 

 

One of the reasons I got shot of my Octavia VRS 184 diesel was the constant regens.

 

Disclaimer: If you read my other posts about the dreadful fuel economy I got out of the thing, I'm quite happy to accept that I bought what we used to call "a lemon" and that others mileage might vary.

Edited 22 June, 20196 yr by john999boy
Speed claims removed as contrary to Briskoda Rules.

On 21/06/2019 at 16:11, PetrolDave said:

So how come the ONLY time this CEL appeared was when I filled at Morrisons - not before and not since???

 

That seems pretty much cause and effect to me...

 

Of course you are perfectly at liberty to disagree

 

Great example of human's poor ability to differentiate between causality and correlation.

 

What is even clearer to me is that CELs do NOT regularly come on for the 15 million other drivers that sometimes fill up at Morrisons.

 

I find the argument that is is a coincidence more compelling than that it is causally related.

 

Of course you are all perfectly at liberty to be wrong

 

One of my best friends  is a chemical engineer at Total and his role is managing refineries, their input crude oil and their output product, and he has also spent a number of years troubleshooting their refinery facilities across the world.

His comment on this subject – buy the cheapest fuel you can as there is very little (if bugger all) difference in what you get at the pumps…

My car has never had a CEL come on for a regen.  What fun am I missing?  And yes, it does regen.  Did it a couple of days ago.

2 minutes ago, skomaz said:

One of my best friends  is a chemical engineer at Total and his role is managing refineries, their input crude oil and their output product, and he has also spent a number of years troubleshooting their refinery facilities across the world.

His comment on this subject – buy the cheapest fuel you can as there is very little (if bugger all) difference in what you get at the pumps…

 

 

The fuel is the same but the additives that the companies decide to add will vary quite a bit, which is where this varied experience of how the fuel responds comes from.

Still of the impression that driving pattern has a greater effect on regen cycles.  If I run in S mode I've noticed its more likely to complete a cycle before my journey is over. Even if just popping across town.

2 minutes ago, MarkyG82 said:

 

The fuel is the same but the additives that the companies decide to add will vary quite a bit, which is where this varied experience of how the fuel responds comes from.

Still of the impression that driving pattern has a greater effect on regen cycles.  If I run in S mode I've noticed its more likely to complete a cycle before my journey is over. Even if just popping across town.

 

Indeed but his comment was related to the stuff you get at the pumps - post additives...

 

Anyhow - I agree that driving style is more of an issue - for example a lead footed foot to the floor driver may get a DPF up to temperature better but will also be producing more particulates due to overfuelling (witness a non-DPF car accelerating hard as an example) so will be more likely to need a regen...

On 21/06/2019 at 20:05, SuperbTWM said:

No, a passive regen, as already stated, is when the load conditions are as such that the exhaust gasses heat up the DPF enough to turn the soot into ash. There is no input from the car at all. Personally, I am of the opinion that cruising on the motorway does not get the DPF anywhere near hot enough to do any passive regenerating but I would happily change my view if somebody showed me some evidence.

 

My MK2 Octavia can certainly regenerate passively when on motorways and dual carriageways.

 

I've posted this graph before, basically I logged a few drives back to back with VCDS, you can clearly see the measured soot level (green line) dropping when the DPF is hot enough:

1 hour ago, Jono said:

human's poor ability to differentiate between causality and correlation.

Human's poor ability to understand the difference between causality in a specific case and endemically.

On 21/06/2019 at 10:16, ExpiredInTransit said:

Noticed that every time I run a tank of Sainsbury diesel my Octavia will regen 2-3 times a week (tank lasts about that long).

 

When you say "every time" Im assuming you've seen this more than once with supermarket diesel.

 

With my car I often find that a regen occurs after re-fuelling, noticed by the fan running fast when I stop the car.

I assume that this is because I reached a level where regen is required but it was prohibited because the fuel level was below a threshold.

At the next refill, regen is allowed again & so starts as soon as the other conditions are ready.

 

I use mainly supermarket fuel but normally a case of whatever is on my route when the warning pops up.

I've never noticed a difference between big brand vs supermarket.