Fabia 1.6 CR TDI 90bhp appalling fuel consumption

[delta925]

'Estate Man'

I don't dispute your comments that due to the driving style some will get significantly lower mpg than others even though they think they are driving economically.

However this does not account for the issue at least a few are having with a 12% or more increase in fuel consumption for a few days / 100+ miles after a DPF regen.

I had my first service and let the local dealer, who took over from my supplying dealer, do it.

I explained my concerns about why the fuel consumption increase was occurring and the potential effect on both the catalytic converter and DPF as well as the cost.

As expected the diagnostics showed no errors and they said the dealer network system had no details of this issue.

Hence 'status quo' ....

[Guest]

HI delta, it's confusing isn't it. The reason for this 'variable' fuel consumption is (it now appears) down to the way modern diesel engines respond to differing driving styles. The more a diesel is driven with economy in mind, ie: light footed, lower revs, higher gears etc, although you may get a reasonable fuel economy initially, this usually starts to tail off and the engine starts using more fuel. This is due to a build up of particulate matter, soot etc that coats not just the DPF, but the CAT, the valves, injectors, pistons etc. Light footed driving encourages this. That lowers engine fuel efficiency. The car responds by injecting even more fuel into the exhaust system to start a regen and burn the DPF clean. This causes a further drop in fuel economy for a day or two. However, the fuel economy then starts to improve, sometimes dramatically and will be ok as long as the owner/driver doesn't spend all their time driving again with a light foot. Driving with a light foot even at 60 or 70 doesn't actually get the engine very hot where it matters. So it's essential to burn it clean often with more revs and load and avoid using 5th gear when it isn't needed. It's an overdrive and often isn't needed when on 'A' or 'B' roads. It hits the economy and dirty's the engine reducing economy. Many drivers of the 1.6cr engines get as much as 10mpg's or more by not using 5th gear. Much of this is down to the way modern engines have to run to comply with emmission rules. Some is down to the fuel we use now which is very different to the diesel of 10 years ago. The fuel itself is cleaner but the way it burns actually isn't when at low temps, which happens at low revs on light throttle. People are finding that once they know this and run the car at slightly higher revs, give it a blast often and just drive it, they fuel economy is darn good and regens are not a problem, happening less often and only at the default times/mileages. But everyone need to get to know the car, the engine sweet spots, and adapt accordingly to how it needs to be driven. The car won't actually adapt to them.

[Guest]

Hi Estate Man,

From previous discussions, I guess what you say about keeping the revs up around 2000+ applies equally to the 1.2TDi Greenline engine. Oder?

Tim

Yes it does Tim. Of course we are talking about general cruising and driving, but generally the 3 cylinder engines like more revs than the four cylinder ones. My 1422cc PD TDI love to rev too. It can, like yours, be driven at lower revs but it's not the best way to get good economy on a run. But speak to some other Greenline 2 owners on here for best advice on that.

[Black]

I can see your argument but why does the gear change indicator suggest the style you say is so bad?

[Guest]

Hi Black, that another confusion isn't it. The gear change indicator is just a guide, and it's something that's a bit gimmicky really IMHO. I've had cars in the past with them, both petrol and diesel. Some electronically controlled and some vacuum switch operated from the intake manifold. Either way, I never found any of them any good. I honestly thing manufacturers don't explain enough about them to customers. In fact, one of the 'surveyed' individuals from last year who was having considerable trouble with his fuel economy (average of just 52mpg) from his 1.6cr Fabia, was so religously following these lights and getting into 5th gear at 14-1500 revs that it totally screwed up his economy. He was one of the individuals that I actually went out with for a drive to see how he was handling the car. After getting him to ignore the lights his consumption went down massively. Overnight he reported getting an average 60 mpg by increasing his revs across the range and not using 5th gear so much. He just thought he had to be in 5th gear as much as possible to get the best mpg. Poor old engine was struggling and regening all the time, and he'd been driving it that was for nearly 10 month! The garage had taken it in for testing 3 times and found nothing wrong. So, we gave it a good blast and altered his driving style and he's doing fine now. He was even considering selling the car and taking a financial hit on it. Not now, he is pleased with it.

Just to be clear, I'm not talking about Mike H.

Edited 19 April, 2012 by Estate Man

[raisbeck]

50,000 miles in my gl1 now. Only 2 yrs old. 5th is a waste of time under 60. Engine is much happier in 4th. 4th is geared almost the same as standard tdi 5th. Gl1 gear ratios are the same as the cr.

I treat 5th as an overdrive or motorway cruise gear. Need to be at 70 to get even 2000 rpm. Engine is designed for max torque 1800-2200. This is IMHO also the most efficient range to be in. 60 I'm 4th puts it at 2200.

[xreyuk]

Personally for me, I've found my engine to be best between 1500-1700 revs for cruising, up at 2000 it's about 10mpg worse. I don't know if my Leon 1.6CR is much different to the 1.4TDI, but it sounds like the revs are the same (mine is 2000rpm at 70mph). I have spoken to other Leon ecomotive owners, most of them finding that theirs is most efficient between 1500-1700rpm too.

My engine is also tight, so I don't know if that will change over time, but according to most driving graphs, generally lower RPM is better, but as estate man says above, you can't go too low otherwise it adversely affects the car (blocked DPF etc).

Estate man - is there a chance that over time running at 2000rpm will become more efficient than the 1500-1700rpm?

Edited 19 April, 2012 by xreyuk

[Guest]

It will certainly become more efficient right across the rev range as the engine beds in further. At the moment your engine experiences expotential frictional losses at 2000rpm than at 15-1700rpm which is accounting for the fairly large increase in fuel consumption at those revs. It will improve but I can't say if it will be more efficient on your Ecomotive engine than at 15-1700rpm. My guess is there won't be much difference between the two rev limits once fully bedded in.

[xreyuk]

No worries, well I'll be watching the average fuel economy over each tank for a while nearly up to 6k now and it looks like it's getting better on the motorway, but I haven't had much time on there, all the jobs I seem to be getting for work at the moment are in the same area so lots of urban/country road driving.

[delta925]

'Black'

My thought about the gear change indication is that the thresholds were not adjusted when the engine was changed from the 1.9 PD to the 1.6 CR.

'Estate Man'

As I've posted before due to the traffic levels on my daily commute there is little opportunity to drive in a more spirited heavier footed style when in a line of traffic at 65-70mph or on urban roads with 20 / 30 / 40mph limits. I never use 5th below 60mph and apart from setting of in 1st select a gear so the revs are never below 1500rpm. A few time I have tried keeping in 4th at 65-70mph for 4-5 miles but every time the displayed single journey mpg is lower.

Ultimately so long as I don't end up with big bills in 5+ years time for a replacement CAT and/or DPF because of an issue from new creating abnomally high levels of emissions for around 40% of the total mileage while my long term average mpg could be around 55mpg rather than 51 I accept the increased fuel use is due to having to meet emission levels and is offset by the low RFL.

[Black]

It is interesting about the light. I do struggle with the idea that the Engineers that designed the engine have set it at the wrong point. Having said that I know form my own experiences driving the car hard does not drop the economy as much as expected so i can buy Estatemans point. Also backed up by the fact that he gets a much better economy than I ever did on my 1.4 TDI!

It may be worth feeding back to Skoda about the light settings!

Edited 20 April, 2012 by Black

[MikeHart]

I Definitely got one of the bad cars, I also believe there is a problem with certain versions of this engine. Further to my earlier post when my car had spent 2 weeks with the dealer I have not noticed the judder since but have noticed 4 regens of the DPF when the idle speed sits steady at 1000 RPM (750 RPM when not regening) the fuel economy seems to have improved by around 5 MPG. Whatever they did to it seems to have improved it, but for me this has all come too late, the enjoyment of driving it has been overtaken by constantly waiting for the judder to happen at every junction or set of traffic lights, and the obsession with fuel economy. This coupled with the dismissive attitude from customer services has led to me trading in for another make. Overall I have been very disappointed with my Skoda experience.

Hello Astra1,

My car is currently in with the dealer and they are trying to recreate the shaking etc., which Skoda central now say is not normal. However, it's very difficult to get a regen when it's in the dealer. Is it possible for you to post the registration plate, garage etc. for your car so they can look up the details of what was done to your car? Might short-circuit things. Skoda technical are claiming they have never heard of the 'shaking during regen' issue, but there are several people on here who have reported it, so they are either not recording it, or lying. Don't know which, but to claim they don't know of it is rubbish. I told them of your experience, but they say no. I've found references to this shaking and low MPG across the VAG range.

Skoda customer services are without doubt the most useless bunch of incompetents I have ever dealt with. The MD totally ignored my email other than to pass it onto customer services. Shame on him. At least an acknowledgement would be the minimum to be expected. The customer services woman is patronising and utterly unhelpful. She refused to look into other records as she was 'interested only in your car'. After talking with the dealership who I had explained had done everything they could, she asked me to phone them for a booking and then had the audacity to ask me to close the problem as she'd done her job!!

I'm told they were good. Well, Skoda centrally now need to up their game massively, but I'm told this is across the VAG group and not just Skoda.

Many thanks,

Mike

[MikeHart]

Hello Mike, I've read your latest posts with interest. Sorry to hear you are still not happy. VAG does seem to have tried to refine the ecu software somewhat on some cars and I gather they have pushed one of the updates out to all the earlier 1.6cr engines as a precaution against too many regens. But, and I know you don't believe this, all the evidence suggests this problem is a driver issue and not a car issue par se! Or the owner has unrealistic expectations of how good the mpg should be for the use the car is put to in the topograhy it is used in. These statements do not rule out the fact one or two cars may have an issue (that's always possible), but VAG's own research on this engine and many others shows this to be the case and is backed up by the way the unhappy posters (most of them in fact) later post back to say all is well. My own research, such as it was shows this to be the case too when I followed 13 owners of this engine in Skoda and VW cars for some 10 months (it was meant to last just 6 but proved interesting to my own diesel engine project so linguered on a bit) who were adamant there cars were rubbish and were in some cases getting high 40's to the gallon when new. Their cars has been checked and shown that nothing was wrong. This included my sisters car incidentally. When some of the dealers suggested it was the driving style and they needed to learn a slightly different technique, as modern diesels capable of very high mpg's couldn't be driven like engines of old, they were outraged.

So, I actually went out to check a couple of the cars in my survey Mike. These individuals lived not too far from me and I was able to reach them easily. The cars checked out beautifully. Nothing I could find wrong. We then went for a drive with me as passenger. It quickly became obvious to me why the cars were doing so badly on fuel. The drivers were going very very light on the throttle all the time (this soots up the dpf and the cat, and doesn't help the injectors and valves either). On top of that they were not giving the engine any real work to do but staying in very high gears at low revs. In fact, many overused 5th gear which is really an overdrive, and not needed in many situations, but people are fixated in reaching 5th gear all the time believing it will give good economy. It doesn't, depending on the situation 4th can be much much better and deliver much high mpg's. As Seboni says earlier in your thread, 2000rpm plus gives good economy, but 1600 doesn't in high gears. The engine doesn't get hot enough to burn stuff clean if you stay at those low revs all the time without giving it some real work to do, and I don't mean just cruising at 70, that's not good either if you do it all the time. The actual speed you do is irrelavent if you don't give the engine some work to do to keep it nice and clean with nice big throttle openings and high revs for sustained periods. This engine is shorter stroke than most diesels and loves to rev. It then gives good economy. It took some time but with advice from me and one or two others on this site, I can tell you all the individuals in my survey modified their driving style and all of them without exception now get brilliant economy and all are happy. Some have posted on this site. I gather this is the case for many of the early posters on this subject too.

Now, clearly I don't know what your driving style is like, so I may be completely wrong, but from reading your posts over time, you are saying the very same things my survey participants were saying about your car symptoms and fuel economy. Since Skoda cannot find anything wrong with your car it suggests you may fall into the same catorgory. Please don't think I'm having a go at you, I'm not. If you want to solve this you have to look hard at all aspects of this. It took some time for me to convince some in my survey (all experienced drivers of some years) that driving style was the thing that mattered most. But they all got there in the end. If there was something wrong with your car Skoda would have found it, believe me. Should VAG issue better/clearer driving instructions for these engines. Maybe! Keep posting Mike as your case is an interesting one. Thanks...good luck.

Hello Estateman,

Thanks for all your replies to my postings and the information is helpful and believe me, no offence is ever taken. I'll follow any route to try and sort this out. Do you have any experience of the shuddering whilst regening? I've tried driving over a few tanks with various styles to see what happens as you suggested this earlier. I did several tanks driving like a granny and then several driving as you say, staying in lower gears etc. and revving the engine much more. The former gave the best MPG and the latter the worst. I then tried driving at various speeds on the dual carriageways. 55-60 gave the best, with MPG plummeting at 70. Not necessarily surprising, although I was surprised by the size of the drop.

There are two interesting things that happen which seem to define this issue for others on this forum. The first is the shaking during regen (which I've had outside of regen as well) and the second is the regen run getting normal MPG, but it then dropping by 10-15% and gradually picking up till next regen. This suggests to me that the amount of soot in the DPF changes the MPG, but interestingly, the more soot, the better the MPG and I would have expected the reverse. Not sure if you have any thoughts on this; all options considered.

What I'm wondering now, is if I was too light footed early on and the engine has become sooted up and even blowing it out now isn't really working. Is there any mileage in using one of the engine cleaners you put in the fuel tank? Might give it a clean out and remove some of this? If so, do you have a suggested one?

Many thanks,

Mike

[Guest]

Hello Mike, nice to hear from you. Look whats happened. We've all been writing loads of stuff about this fuel consumption thingy!

Back to your problem. I think using one of the fuel additive cleaners is a very good idea. Seb, on this site has used BG244 (I think) which is one of the very best you can get. It will clean the inside of the engine and particularly the injectors. Check this but I believe it is DPF friendly too. Only use a DPF friendly additive. If you don't want to use that one then just use any other fuel system cleaner that is DPF friendly. But the BG244 is the very best (and most expensive). I have not used it myself, but many individuals on this site swear by it. It will make a difference I'm sure.

With regard to the shaking of the engine during regen. My sisters Fabia with the 1.6cr engine (105ps) started doing this during the first 2k miles. It wasn't bad but she did notice it. At that time she was driving the car in higher than needed gears at lower revs. Her fuel economy was not brilliant but not good either. After we had been out in it to see how she was driving and we modified her driving style, things started to change. Within a week or two of revving it more, the shaking reduced then stopped. After a month, the engine was giving 68-70mpg easily in 4th gear at 55-60mph. On the long motorway trips she does once a month she achieved 62-68mpg at 70mph in 5th. My theory is that the engine was sooting up and carbon was forming on the valves and elsewhere lowering performance, both fuel and power. It also caused the engine to shake when regening at idle. Since then she has not looked back. The car is completely different. She has nearly 14k on the clock now and is very happy with it.

If you do try the engine cleaner, do let us all know Mike how you get on with it. Good luck mon amie!

[MikeHart]

Hello Mike, nice to hear from you. Look whats happened. We've all been writing loads of stuff about this fuel consumption thingy!

Back to your problem. I think using one of the fuel additive cleaners is a very good idea. Seb, on this site has used BG244 (I think) which is one of the very best you can get. It will clean the inside of the engine and particularly the injectors. Check this but I believe it is DPF friendly too. Only use a DPF friendly additive. If you don't want to use that one then just use any other fuel system cleaner that is DPF friendly. But the BG244 is the very best (and most expensive). I have not used it myself, but many individuals on this site swear by it. It will make a difference I'm sure.

With regard to the shaking of the engine during regen. My sisters Fabia with the 1.6cr engine (105ps) started doing this during the first 2k miles. It wasn't bad but she did notice it. At that time she was driving the car in higher than needed gears at lower revs. Her fuel economy was not brilliant but not good either. After we had been out in it to see how she was driving and we modified her driving style, things started to change. Within a week or two of revving it more, the shaking reduced then stopped. After a month, the engine was giving 68-70mpg easily in 4th gear at 55-60mph. On the long motorway trips she does once a month she achieved 62-68mpg at 70mph in 5th. My theory is that the engine was sooting up and carbon was forming on the valves and elsewhere lowering performance, both fuel and power. It also caused the engine to shake when regening at idle. Since then she has not looked back. The car is completely different. She has nearly 14k on the clock now and is very happy with it.

If you do try the engine cleaner, do let us all know Mike how you get on with it. Good luck mon amie!

Hello again,

I think I'll try this. It's at the dealership at the moment and they're trying to get a regen so they can see the shaking. Murphys law says that it won't happen though!! My car has now done about 25,000 miles, so if it's clogged up and generally fouled, presumably it will need either the very best cleaner, or several doses of a lesser one. I guess the clogging could be quite bad. I've found the BG244, but only mail order. I might try something from Halfords for speed (Wynns or similar) to start with and if I start seeing results, either go for the BG244 for the full job, or maybe use another Wynns and do it over a few tanks. I suspect the clogging might be bad enough to take more than one go, even if BG244. Might check with the dealership and see if they have anything either. If I want something quick from Halfords (or similar) to get the ball rolling, do you have a favourite. I know they do Wynns and STP amongst others.

Thanks,

Mike

[xreyuk]

Using today as an example, these DPFs are a pain in the arse.

I did around 600 miles last week, 500 miles of motorway driving at 70mph, 50 miles of country roads and 50 miles of city driving.

This morning, started the car, and drove about 10-15 minutes, and before I know it the car is doing a regen. It's beyond me how after that much motorway driving it can be over 45% clogged (when a DPF regen starts)

[Guest]

Hi xreyuk, incidentally, I've got your PM and all of what you describe is completely normal, strange that it may sound. That's how all the Fabia's behave too.

For everyone's benefit concerning your last above post, your car was just doing a default regen I'm sure. These are included in the common rail engines to make certain you get the best life from the DPF and the fuel economy stays at a good level. As you have found out, this causes a temporary lowering of the average economy for a few minutes as the computer takes account of the extra fuel used to regen.

[MikeHart]

Using today as an example, these DPFs are a pain in the arse.

I did around 600 miles last week, 500 miles of motorway driving at 70mph, 50 miles of country roads and 50 miles of city driving.

This morning, started the car, and drove about 10-15 minutes, and before I know it the car is doing a regen. It's beyond me how after that much motorway driving it can be over 45% clogged (when a DPF regen starts)

You're lucky!! Mine seems to regen every 300-350 miles. About once a week in my life. This suggests the engine is burning dirty, which might be for many reasons. Whether this is the management system not working properly or me driving in an unsuitable style, I don't know. I've tried driving in various styles over the 18 months I've had it, and nothing seems to make a difference. Not saying this excludes driving style, but I have tried driving with higher revs and couldn't detect a difference. I find it rather interesting that motor manufacturers call things like DPFs an advance (they created them!!), but when you have to drive a car in a specific way to prevent the engine sooting up etc., it rather seems like we're going backwards. Obviously, driving style could affect economy, but it shouldn't affect reliability etc. unless grossly out of spec. This sooting up if you don't rev it hard is silly. There must be loads of drivers out there (old granny for instance :-)) who simply don't drive like that. Should Skoda (maybe VAG) put a caveat on their diesel cars that says old people shouldn't buy them?

[Guest]

MIke, if you have done 25k then giving the engine a good clean out is a very good idea. It will be dirty. You may notice the engine running a bit rough for a day or two once you have put the cleaner in the tank. That's fairly normal if the engine is very dirty inside. But it will improve quite quickly normally. I've always used 'Millers' fuel system cleaner. I think they make a DPF friendly one too. Millers is what we used in the trade so I've just stuck with it. But they are all pretty good, but BG244 is the best everyone reckons.

[xreyuk]

I never realised that they did 'default' DPF regens. I can live with that, but I don't understand how the fuel consumption was so bad for 100 miles after it!

I also have used Millers Ecomax, which appears to have helped a bit as the engine feels better. I researched it before I bought it, and there have been a few people who e-mailed Millers to ask, and Millers have said it's okay to use it with a DPF, Euro IV/V compliant car.

[MikeHart]

I never realised that they did 'default' DPF regens. I can live with that, but I don't understand how the fuel consumption was so bad for 100 miles after it!

I also have used Millers Ecomax, which appears to have helped a bit as the engine feels better. I researched it before I bought it, and there have been a few people who e-mailed Millers to ask, and Millers have said it's okay to use it with a DPF, Euro IV/V compliant car.

Thanks for the information. The poorer economy after a regen really confuses me. Surely, the worst performance and economy should occur when the engine is dirtiest (i.e. soot in the DPF)? So, why does my car (and it seems yours) get better economy as the DPF fills up? Wouldn't this make extraction of the exhaust fumes less efficient?

[raisbeck]

Hello Estateman,

Thanks for all your replies to my postings and the information is helpful and believe me, no offence is ever taken. I'll follow any route to try and sort this out. Do you have any experience of the shuddering whilst regening? I've tried driving over a few tanks with various styles to see what happens as you suggested this earlier. I did several tanks driving like a granny and then several driving as you say, staying in lower gears etc. and revving the engine much more. The former gave the best MPG and the latter the worst. I then tried driving at various speeds on the dual carriageways. 55-60 gave the best, with MPG plummeting at 70. Not necessarily surprising, although I was surprised by the size of the drop.

There are two interesting things that happen which seem to define this issue for others on this forum. The first is the shaking during regen (which I've had outside of regen as well) and the second is the regen run getting normal MPG, but it then dropping by 10-15% and gradually picking up till next regen. This suggests to me that the amount of soot in the DPF changes the MPG, but interestingly, the more soot, the better the MPG and I would have expected the reverse. Not sure if you have any thoughts on this; all options considered.

What I'm wondering now, is if I was too light footed early on and the engine has become sooted up and even blowing it out now isn't really working. Is there any mileage in using one of the engine cleaners you put in the fuel tank? Might give it a clean out and remove some of this? If so, do you have a suggested one?

Many thanks,

Mike

There is a lot misinformation being placed on here about DPF and how it works. I did loads of research in to DPF before I bought my Greenline and I have to say the DPF is a total non issue for me. Some DPF designs, more so earlier versions dont have active regen, they use typically a cerium based catalyst to reduce the light off temperature in which case yes, a good run now and again sorted it all out. Disadvantage is the catalyst reduced the longevity of the DPF by non removeable ash. On the new Skoda the DPF is under the vehicle, doesnt use a catalyst, there is no way you are ever going to keep that thing clear by driving style, any passive regen is going to be minimal at best. it has to have the post fueling regen to get it hot enough to clear. Same applies on my car, I drove home from the Midlands to South Coast motorway all the way giving it some beans and it still regenerated at its usual 120-140 miles. Mine regens nearly every day as I do 100 miles plus, its done this since new and when when it regens its a non event, slightly noisier exhaust for 5 mins and lose a little bit of boost. All this waffle about taking the car out for a good run to clear the DPF is pure bunk. Only time you would do this is if you have been doing ridiculous short journeys not allowing the regen system to run a cycle and you get the DPF warning light. Any 'quick blast' will just fill the DPF until the next Regen. You dont have to change any driving style at all for a DPF, cane it, granny it....drive it how you like, but that Fabia will just go on collecting soot until the next active regen.

[xreyuk]

I don't think your comments about the DPF are correct, because I, like you, have done my research. Also let's not forget Estate Man is experienced with diesel engines.

The purpose of a regeneration is to raise the exhaust temperature to a point the soot begins to burn off. Giving it some beans and driving on the motorway raise the exhaust temperature high enough to burn off the soot, thus the car doesn't need to regenerate.

Also, I drive more miles than you a day, and I certainly dont regenerate anywhere near as much as that.

http://www.theaa.com/motoring_advice/fuels-and-environment/diesel-particulate-filters.html - Are you going to suggest the AA is wrong too?

Edited 24 April, 2012 by xreyuk

[MikeHart]

There is a lot misinformation being placed on here about DPF and how it works. I did loads of research in to DPF before I bought my Greenline and I have to say the DPF is a total non issue for me. Some DPF designs, more so earlier versions dont have active regen, they use typically a cerium based catalyst to reduce the light off temperature in which case yes, a good run now and again sorted it all out. Disadvantage is the catalyst reduced the longevity of the DPF by non removeable ash. On the new Skoda the DPF is under the vehicle, doesnt use a catalyst, there is no way you are ever going to keep that thing clear by driving style, any passive regen is going to be minimal at best. it has to have the post fueling regen to get it hot enough to clear. Same applies on my car, I drove home from the Midlands to South Coast motorway all the way giving it some beans and it still regenerated at its usual 120-140 miles. Mine regens nearly every day as I do 100 miles plus, its done this since new and when when it regens its a non event, slightly noisier exhaust for 5 mins and lose a little bit of boost. All this waffle about taking the car out for a good run to clear the DPF is pure bunk. Only time you would do this is if you have been doing ridiculous short journeys not allowing the regen system to run a cycle and you get the DPF warning light. Any 'quick blast' will just fill the DPF until the next Regen. You dont have to change any driving style at all for a DPF, cane it, granny it....drive it how you like, but that Fabia will just go on collecting soot until the next active regen.

Hello Raisbeck,

I think what was being said was about soot elsewhere in the system and general crud collecting on valves and things like that through the system. I don't think anyone was suggesting a blow out could clear the DPF, but that it might clean other bits, hence me asking about putting a cleaner through. I've looked under the bonnet of my car and the DPF is located at the back of the engine bay. It is easily identified by the large amounts of heat shielding around it and when I've stopped during regen, you can feel the heat pouring off the device at the back. Whilst regen distances seem to vary a bit, I would be very concerned by one every 120 miles. That sounds like way too often. Obviously, it will be affected by the brand etc. of diesel and I'm sure different ones give off different amounts of soot. I don't know, but I would have thought long motorway runs should produce less soot than shorter runs.

Thanks,

Mike

[Guest]

Hello Raisbeck, don't often disagree with you about anything. But, Mike is correct in as much as we are all talking about the effect of soot on the economy of the engine. But I can see why you may have thought otherwise. As you are most likely aware, the DPF forms a central part of why economy seems to be so affected on 1.6cr engines after regening and it regens more I've found if the engine is driven in higher gears at lower revs. I've realised this after studying owners with this engine, and my own bench testing on our new diesel engine development, on which we are running a NOX cat too. Driving at lower revs, light throttle etc soots the engine internals, which then gets passed onto the DPF. Incidentally, the DPF unit is a combined Cataylist & DPF in one. All diesel engines are required by law to have a catalyst, just as petrol cars are, to reduce the Carbon Monoxide and convert it to Carbon Dioxide and water, but you know all that. What I and my colleagues have discovered is that soot builds up remarkably quickly in the DPF when on light throttle for very long periods of mixed driving. Back pressure can increase alarmingly quickly on some engines and drastically affects fuel economy. Although, I agree with your statement that the DPF itself is a completely non issue for mostly everyone. They don't normally give and trouble at all and seem to last the life of the car or truck when you look back over history, no matter what type of DPF it is (paper disposable ones excepted). So people shouldn't be worried by the AA report, just be aware of it.

Edited 24 April, 2012 by Estate Man