How often should the DPF be regenning?

[phil5556]

I'm noticing that quite often my VRS is idling at 1000rpm with a bit of a stutter - which I have assumed is the DPF doing it's thing.

It probably happens about every 300 miles.

My commute is fast A roads and I don't pootle about in low gears so wondered if it was a bit excessive?

We have a VW T5 van with DPF and I think I've noticed that doing it a couple of times since we've had it, definitely not every tank full. Unless it's more discreet about it?

[Jevpls]

Unless it's more discreet about it?

 

If you aren't being idle then you might not have noticed it. Probably the best way to see is monitoring the fuel consumption. If it consumes usually ~5 l/100 km and if it raises to 6 l/100 km for some while then it's probably because of DPF.

That can be done only on flat terrain because that's the only way of getting even fuel consumption. Driving uphill/downhill changes fuel consumption every second and you won't be able of seeing any increase.

[silver1011]

The DPF is pre-programmed to attempt a regen at set mileage intervals, regardless of the soot loading. If the DPF is now regenerating more frequently than before then something has changed. Assuming it isn't the journey type, fuel quality or oil specification then it could be on it's way out. 

 

The DPF on the older PD170 engine fitted to the vRS is well documented to be a bit of a problem child, especially as the car ages and the mileage increases.

 

I had a 2007 (57) PD170 vRS that at around 70,000 miles / 5 years old started to get problematic. By problematic I mean that it's presence became more obvious in a similar fashion as you describe. The higher RPM's is normal, the jerkiness, uneven idle and increasing amount of regens is not. As it turned out for me it was a clear indication that the DPF was simply getting tired, it was nearing the end of it's life.

 

I covered high mileage, steady motorway runs but regular (daily) fast A road stints too, virtually no city or stop/start driving, this still wasn't enough to save the DPF.

 

Each time the DPF regens it burns off the soot leaving behind a small amount of ash which remains inside the DPF. As the level of ash increases it begins to cover the internals of the DPF making it less efficient which in turn prompts more and more regens. It sounds to me as though you are entering this stage of the DPF's life.

 

There are other documented issues relating to the DPF too, the mass VOSA initiated injector recall had an adverse affect on the life of the DPF for a worryingly large number of owners. The sensors that control how and when the DPF regenerates are a known weak point on older cars too but more often than not these result in a warning light on the dash. 

 

If the only symptom you have is a noticeable increase in the number of regens then you should be good for a while yet, once you start seeing the DPF light forcing you to drive the car at a set RPM for a few miles then it will be time to make a tough choice, replace it with a brand new OEM / Skoda DPF @ £1,200, replace it with a patented aftermarket DPF £600, have the current one professionally cleaned @ £250 (a short term fix, the problems very quickly return) or have the insides of the DPF professionally gutted, welded back up (to pass the MOT) and the DPF sensors mapped out for £450.

 

It is very possible on a 2008 that you might have the later CR170 engine fitted as this was the crossover year. The CR (Common Rail) engine was designed to work much better with it's DPF and includes a catalyst to help keep the temperatures up for easier passive regens (where the soot is burnt off through normal driving thus reducing the number of active regens required), if this is the case it might be worthwhile getting the car scanned for any fault codes. The DPF's on the CR engines are mostly affected by duff sensors, some of which can begin to fail before bringing on the EML (Engine Management Light) or glowplug light.

 

[phil5556]

Thanks. I shan't worry about it just yet, but will keep an eye on it. Having posted this I haven't noticed it doing it since, I have switched to "posh" diesel for the last couple of tanks, although I doubt that's made any difference.

I have scanned it and no codes (apart from one about taking the light switch out) and no engine lights or DPF light.

I'm pretty sure it's a PD but tbh can't remember what it looks like under the bonnet

I'd like to do away with the thing completely but keep hearing rumours that MOTs are going to start checking for them and I drove past a VOSA checkpoint the other day which got me thinking....

[Ali1987]

Hi im a newbie can any 1 help me I brought a second hand 2010 octavia vrs dsg desiel iv changed throttle body an 5 pin clip because it was damaged now 1 fault left 008213 Iintake manifold flap position sensor bank 1

An p2015-000-implausible signal

[Ali1987]

What can I do mechanic sed need new inlet manifold runner the car doesn't lose power its ok an wen I open the bonnet it feels like iv opened the oven door is that normall thanks

[phil5556]

Start a new thread so people will be able to find your question

[Ali1987]

Ok thanks

[phil5556]

A quick DPF update incase anyone is interested.

So it is a PD BMN engine.

I've done a couple of thousand miles since starting this thread. I've been sticking to using posh diesel, mostly BP Ultimate and Shell V Power or whatever it's called now.

My daily commute is still A roads but I use 6th gear less, only if I'm sitting over about 60. Also done a decent 900 mile motorway trip.

I'm not sure if it's the better fuel, not sitting at low revs in high gears or the better fuel but I haven't noticed a single regen in a couple of weeks now. So something seems to be working.

Either that or is just coincidence that they've been happening while sitting on the motorway.

I bet it starts doing it again tomorrow morning now I've posted this :/

[mannyo]

If you have not had the DPF pressure sensor replaced, then it maybe worth considering doing so. Early ones were prone to failure, and it can fail but not trigger any faults because the ECU still sort of understands the readings. Eratic Regens because the car thinks the DPF is more clogged than it really is could be a possibility.

[phil5556]

If you have not had the DPF pressure sensor replaced, then it maybe worth considering doing so. Early ones were prone to failure, and it can fail but not trigger any faults because the ECU still sort of understands the readings. Eratic Regens because the car thinks the DPF is more clogged than it really is could be a possibility.

No I haven't but I have just changed it on our VW Transporter after it threw up a fault code.

[pikpilot]

I'm not sure if it's the better fuel, not sitting at low revs in high gears or the better fuel but I haven't noticed a single regen in a couple of weeks now. So something seems to be working.

Either that or is just coincidence that they've been happening while sitting on the motorway.

 

 

 I can tell when mine is in DPF regen as the mpg falls by 10mpg.

 

This is a true comparison as the journey is always the same and starts from home and then onto a dual carriageway less than a mile from home.

Normally, once the engine is hot, the average mpg shown on the display is 55 mpg. 

When in regen, it shows 44 mpg at the same point and continues at this level for about 20 miles before climbing back slowly to the norm.

 

I use cruise control on this route as the road is quiet and this puts the rpm within the range for regeneration.

 

Between these longer trips I do a lot of short journeys (I know I shouldn't !) so perhaps I need more regen than some other drivers.

 

So when you are the motorway, check your average and instantaneous mpg occasionally and see if there are periods when the figures are lower than you expect. 

[phil5556]

I've never noticed the mpg change significantly on the motorway. It slowly climbs and falls depending on how I'm driving.

And 55mpg?! I don't get anywhere near that unless I reset it sitting at 60 with the cruise on.

Real world I get 47 on a decent run which I'm more than happy with, and 41 on my daily commute with usual running around.

[pikpilot]

And 55mpg?! I don't get anywhere near that unless I reset it sitting at 60 with the cruise on.

Real world I get 47 on a decent run which I'm more than happy with, and 41 on my daily commute with usual running around.

 

Perhaps that is the difference between a Vrs and my 1.6 litre 77 kW engine. On country roads, and with some anticipation of the need to slow down, I get over 60mph.

[phil5556]

Ah, I assumed you were talking about a VRS too.

I can't complain, I bought it knowing it wouldn't be the best on fuel. It's better than the X Type it replaced and quicker