DPF regen causes diesel to be not as cheap as you think shocker…

Twice in 1200 miles, resulting in my car now at 39.9mpg average.

FFS

Not a regen issue as such , but when mine does do a regen i lose about 5-7 mpg for that tank ! .. the mpg just plummets ! .. lowest ive seen is 49.7 mpg .. which compared to yours is good

I’ve done 18000 miles in my mk3 focus from New and never noticed a regen happen. I must have a dpf on a 2014 car surely.

Jesus! My 1.8t petrol Octavia vrs can achieve that. What car is it?

Thats 39.9 during a 25 miles round trip with 20 miles on the M25 stop start and the regen happening for most of that.

I have read in some cards its not as obvious as others. In our Ford Kuga, and can feel it going a bit flat. I the Alfa (this one) it goes flat for 10 minutes. In fact 2 days ago I had a seized rear caliper fixed, and I has a minor panic think it’d seized back on, pulled over and felt the rear disc & caliper, which were warm and the same both sides, it was then I noticed the lumpy tickover – another sign of regen.

I would add that the same journey came out at 46mpg with no regen last night.

A regen is the last resort for burning off particulates – normally if your journeys are too short / low engine load so the exhaust does not get hot enough to burn them off unaided.

DPF regen

A what now?

Every day’s a school day. Now I know what’s causing my intermittent hot and smelly rear end (arf). Initially thought it might have been brakes (on exhaust side) binding, but inspection resulted in no burnt fingers. Thanks!

Interesting PH thread on this

A regen is the last resort for burning off particulates – normally if your journeys are too short / low engine load so the exhaust does not get hot enough to burn them off unaided.

Using Google, you’ll find a lot of cars initiate the cycle every 300 miles or some such interval. I’ve done 1100 miles in 3 weeks, mostly m/way and all with BP Fuel (1.5 tanks Ultimate, the current normal).

Diesel it Satan’s fuel!!! Trust me I’m an engineer*…

*automotive engineer – so for once it is a semi relevant thing to claim!

Diesel’s day is over, wouldn’t buy another personally.

Nitrogen Dioxide init

My Leon would suffer really poor MPG when regening…. but then it’s method of raising the engine/exhaust temp is to chuck loads more fuel in!

Yeah, mine comes on at annoying times and takes 15mins of less power, delayed throttle response, burning smells and a wheezing engine sound.

It would be great if cars could let you know when one is coming up and you decide when to instigate it (up to a point), by pushing a button. That way you could time it for a longer run instead of during a short trip that may be less time than the regen time.

I’ve not noticed mine entering the regen cycle but if you add in the Webasto auxiliary heater kicking in during this cold snap the between fill average is now in the very low 30’s.

I know I should have gone for more cylinders and a supercharger.

One of the certainties of Alfa ownership is a disappointment that it doesn’t work as well as it looks.

Diesel’s day is over, wouldn’t buy another personally.

Nitrogen Dioxide init

* 😐 while waiting for first ever diesel car to be delivered *

I know I should have gone for more cylinders and a supercharger.

Yes, if buying new I’d buy one of the new 60mpg petrol engines. I needed a cheaper 5-6yo car as a stop gap though.

I’ve been out to several breakdowns where the reported fault is “burning smell and stop-start not working”. So I explain that it is’t a fault, simply the ecu trying to do a dpf regen.
People I have been out to complain it always tries to do the regen at stupid times, a particular favorite seems to be as you pull onto the drive so it sits there gently smoking and stinking the house out.

I know I should have gone for more cylinders and a supercharger.

Yes, if buying new I’d buy one of the new 60mpg petrol engines. I needed a cheaper 5-6yo car as a stop gap though. [/quote]

Nope, not new as they stopped making them over 7 years ago and definitely nowhere near 60mpg. Talking about an S-Type R (V8 400+ horses), whereas I bought a V6 2.7D on a whim without thinking too much about it. Lovely car, roof racks for the bike but low 30’s from a diesel after a MK3 Mondeo TDDI and close to 50 bit of a shock.

My wife’s Fiat 500 multijet does a regen around every few hundred miles or so depending on how its driven. The dpf light has only ever come on once a 70mph blast in 4th up the motorway cured that. Average mpg is around 52-55. We were told in no uncertain terms by the fiat dealer not to buy a diesel with a dpf for pootling around town. She does a lot of motorway driving, its never been a problem. We tested a 1.2 petrol 500, my farts are more powerful.

So really the title should be – diesel car not suitable for stop start journey on m25 shocker.

* while waiting for first ever diesel car to be delivered *

*While having just purchased my second diesel but seriously not giving a shit what people on STW say*

New car needs an Italian tune? 🙂

DPF regen

A what now?

Its like in Doctor Who

Kryton now looks like Peter Capaldi. If it happen again he’ll look like Idris Elba

[Spoiler alert]

I know I should have gone for more cylinders and a supercharger.

No, more cylinders and swap supercharger/turbo for cc 🙂

Sorry, but the reason your car is “only” doing 39.9mpg is because you can’t drive for s**t.

(A single DPF regen uses approximately a maximum 150cc of fuel to light off the trap. Your car has a fuel tank that holds probably 60 litres.)

Sorry, but the reason your car is “only” doing 39.9mpg is because you can’t drive for s**t.

Educate me, oh wise one.

Kryton57 – Member

Thats 39.9 during a 25 miles round trip with 20 miles on the M25 stop start and the regen happening for most of that.

Depending on what you mean by ‘stop start’ I would say that 40mpg during driving that consists mainly of accelerating, braking or sitting still not moving isn’t too bad…..

Perhaps you are expecting too much from a diesel?
If you aren’t moving, you aren’t doing your fuel economy any good and if you are constantly accelerating and then having to brake you aren’t going to get massive mpg numbers.

Coming to work today my mpg was up to about 56 before I hit the back end of the normal traffic on the A14, about 25 miles into my commute. By the time I got moving again up to ‘normal’ speeds, it was down to 50mpg. And because you are sat still for so long with your mpg dropping, it takes longer for the average to come back up.

This is a shocker? I thought the was common knowledge! I’ll be going back to petrol soon as I’m no longer doing the miles to warrant owning a DPF equiped car, that and modern day patrols get good enough mpg for my liking.

Indeed stumpy, its not me that’s arguing my MPG is crap and my driving skills are at fault.

A regen won’t help it either. Maxtorque needs to read the thread – for the 3 weeks I’ve had the car either some or all of that time has also been spent with the rear caliper binding. Hence in the 45 minute journey after it was fixed, from Dunstable to North London sandwiching the M1 and M25 between the rush hour traffic at each end the car averaged 51.8mpg.

But my LIFESPAN OF THE CAR MPG is showing 39.9 I suspect influenced by those reasons, and who knows, maybe the previous owner drove around town all day for the 3 years he had it.

I’m also getting new boots in Monday as mine really are the shitiest tyres in the world. After that I’ll reset the Total trip/average/range and see what I on the fixed setup.

My journey during the week is 8 miles each way, I travel fairly good distances for leisure purposes at weekends.

My DPF is not even noticeable, no issues and consistent performance.

Love diesels.

so 39.9mpg is average for the trip or cumulative average? If it’s cumulative average and you don’t know when that was last reset, then why not just reset that and see how you get on?

My Wife’s Ibiza (with dpf) is a 2 litre with 140bhp & until recently she was averaging around 50mpg on her ‘through town’, fairly stop-start commute.
Now she’s doing a longer, more free flowing commute she is regularly seeing 60mpg average on the computer, so even accounting for several % of optimism on the computer’s behalf she is still getting 55mpg or so.

I drive her car every now and again, and can’t say I’ve notice it doing a re-gen. How do you tell?

Her previous 1.6 petrol 308 struggled to get 40mpg.

I’ve had 2 cars now that allegedly contain dpfs (f20 and f25). The car does lots of school runs and the odd motorway run.

I have never once noticed this dpf regen thing you mention.

I’m now close or maybe just below the break even point for petrol v diesel but prefer the way this engine feels to its equivalent petrol.

How do you tell

Common signs on older Alfa’s

a) Performance is slightly flat
b) If you are looking at current fuel consumption, it’ll be very low in comparison to the normal
c) Slightly jittery rev needle at idle
d) Car smells hot/burning smell if its still and you are outside the car
e) The Alfa turbo needle drops “suddenly” off revs, rather than the usual gradual retreat.

Thats from the Alfa forum and ties up with my experience with the exception of the turbo needle that I wasn’t watching.

I have never once noticed this dpf regen thing you mention.

It might not kick in as it hasn’t met the parameters – continious running of the engine at constant speed etc. It’ll keep going and filling up with soot for thousands of miles perhaps until the DPF gets to a point where the ECU will force a regen – you’ll get a light on the dash, and the garage should tell you to go an drive along a motorway or similar for an hour at mid revs / 60/70mph.

I had to go through the whole diesel/petrol thing this time last year.

I only do 15k a year but it’s all long journeys (cycle to work, supermarket is 1/4 mile away and quicker to walk, Big shops done on the way back from somewhere if needed) so the short journeys issue didn’t factor into it. Even taking into account the equivalent diesel engine would get 10mpg more than the petrol one I bought the added cost of purchase, servicing and the usual life of the DPF, DMF and depreciation meant the petrol came out cheaper by a decent margin. The fact that I’m actually getting better mpg out of my car than the book suggests (50mpg vs 47.6) means I will always be better off with the petrol.

Depreciation is the biggest cost on any car, fuel is just more noticeable as it comes out of your pocket every time you fill up.

Wait – you mean automatic regens, rather than taking it to the garage?

You’ve got 40mpg and you’re doing lots of stop start journeys? That’s not too bad on a brand new car if you ask me.

Anyway – re DPF regen – there are two kinds, in VAG land at least (and probably others, BMW I think). There’s passive regen, where it advances timing and reduces EGR to get the exhaust temperature up. You should not notice this in terms of performance, but it might sound different. This uses no extra fuel, and will work fine in normal driving. If you aren’t driving it enough for this to work, it then initiaties active regen, which is where it’s squirting extra fuel into the exhaust stroke which oxidises on the DPF cat and increases temps to burn the soot. This would harm your MPG.

I think it tells you it’s doing this, because it doesn’t want you to stop the car when this is happening. If you do, it’ll then put a light on and according to the manual you need to take corrective action – take it for a dpf cleaning drive.

EDIT oh.. is your car not brand new? In that case.. on the previous thread.. some people are only getting 40mpg from their diesels.. and some are getting 60. There’s a knack to it, don’t expect the car to do all the work…

Depreciation is the biggest cost on any car

Not of anything I’ve ever bought 😆

Maybe I’ve been lucky but since going diesel (170 common rail vag units in both cars) we currently do twice as many miles to the same amount of fuel as our previous petrol cars did whilst the performance in most circumstances is better.

Some very bold claims from the very latest petrol cars but they feel so slow at low revs you have to push them to get anywhere and then the mpg drops off the table.

My neighbour recently had one of those 1 litre 3 cyclinder turbo fiestas which have won many awards. Driven at all spiritedly it would drop below 30mpg on a combined route. The forums are full of many unhappy owners who purchased for the potential fuel savings.

http://uk-mkivs.net/topic/31023-dpf-regeneration-information-must-read-for-all-drivers-of-dpf-equipped-cars/

Noddy question (and I don’t own a diesel) Can an owner do manual a DPF clear out? i.e. empty out the accumulated particulates by hand/bag them out and take them to waste disposal for themselves? or is it a garage only job?