DPF - MGP and rev limiting - Monte Carlo 105 CR

[A Laws]

Okay its been a while since I last roamed the forums when I had my Fabia VRS, but we've recently purchased a Fabia Monte Carlo CR 105.

 

The car is a 2011 with 17k on the clock so not brand new.

 

The issue I seem to have is that the MPG we are getting is very low compared to what we got on the VRS and IBIZA TDI sport.

 

We are averaging 39 MPG doing 20 mile journeys on A roads and dual carriageways.

 

I've also noticed that post arriving home via the dual carriageway the car always does into DPF bypass - Revs at 1k rpm, noisy and smelling.  

 

Now when it goes into this PDF mode it also limits the rev range when out of gear to 2.5k rpm.

 

Now if the car was new I could understand it going through the learning process etc but this should be broken in.

 

To me there seems to be an issue however the cars showing no fault codes.

 

Is it just me, or does seem to indicate an issue with the car - 39 mpg is very low - the VRS and IBIZA both averaged 51 MPG ?

 

Your thoughts would be greatly appreciated

[Huskoda]

It could be the car had a previous life unsuitable for DPFs and they filled it, hence why the owner got rid. I would have it VCDS scanned for ash content.

[bobjob49]

My mpg dropped when I had a failed lamda sensor. Did not notice any rev limit though.

[fabiamk2SE]

My mpg dropped when I had a failed lamda sensor. Did not notice any rev limit though.

Yeah. That should trick the engine into thinking it needs more fuel for the right mixture. Then actually making it run too rich.

It wont limit the revs in any way. Just gives it the wrong mixture.

[threadbear]

My Fabia is rev limited in neutral to 2500rpm. Seems to be the norm for this engine. My car also did regular regens at similar mileages as you are suggesting. Much less common at 44000+ miles. Or at least less obvious.

[A Laws]

As threadbear has indicated it seems normal that the revs are limited when in neutral.

 

Which just leaves the low MPG and DPF operation coming on every other day.

 

The OBD scanner i have is picking up no faults, whichI would assume would pick up a Lamba fault?

 

Also the Ash content that Huskoda is recommending is just purely a count?

 

If so what am I looking at for being good good/bad?

[GeneralPurpose]

A Laws, nice choice of motor. They are good. 

 

I note you are a new owner to the 1.6cr engined Fabia. Low mpg's are often a sign of a new owner to this engine. The reason the car is regenerating the dpf so often is indicative of maybe several things as the guys are saying. It's may also be indicative of the fact you or your wife haven't yet learned the right driving technique for this engine. It's worth experimenting. No offence is meant by those comments but it's proven to be the biggest single factor of low mpg's on this 1.6cr engine. Driver technique! Of course, also on what sort of roads/hills/journeys etc. That may sound a funny thing to say but it's often true. This engine likes to rev, it's a short stroke diesel engine by comparison to the previous versions. Revving it a bit more makes it run efficiently. Ignore the economy lights on the dash. They make you change up into a higher gear too early and this lowers your engine revs often too much. 5th gear should not be used under 55mph and preferably not until 60mph. It's a genuine overdrive and it makes the engine labour if used too soon. This increases the amount of fuel the engine uses. We found staying in 4th gear on 'A' roads gives much better mpg's than 5th gear. What sort of speeds to you drive at on those 'A' roads? You may just need to give the car a good clear out on the dual carriageway for several miles. If non of that makes an impact on your mpg's then a visit to the garage for a check up could be of benefit. 

[A Laws]

Well my wife isn't one for changing up too soon and usually drives A roads at 50-60 and dual carriageways with an appropriate increase.

 

The cars also has a few 'clearouts'.

 

An example is when on DC at 70 + 10% speedo error the car is only giving an average consumption of 44 mpg with cruise engaged over a 20 mile stretch after its fully warmed up - This just seems a bit low

[iSamage]

Well my wife isn't one for changing up too soon and usually drives A roads at 50-60 and dual carriageways with an appropriate increase.

 

The cars also has a few 'clearouts'.

 

An example is when on DC at 70 + 10% speedo error the car is only giving an average consumption of 44 mpg with cruise engaged over a 20 mile stretch after its fully warmed up - This just seems a bit low

Thats low. If you're not carrying excessive load, that number should be in the high 50s low 60s at 70-77mph. Trust me! Ive only ever seen a figure that low today and a couple of weeks ago, when the car was lugging 5 people and 110kg luggage to the airport. It sounds to me like the car has had a former life which wasn't exactly DPF friendly. Does it have any warranty left?

[A Laws]

Yep only 3 weeks ago we purchased it so got a years skoda warranty - Just wanted to make sure I wasn't being hypercritical before I take it back

Edited 23 August, 2014 by A Laws

[iSamage]

The only confusing thing to me is that if the DPF was full (or near enough), and a long run doesn't clear it, there should be warning lights showing on your dash....

[Gino4]

I have had my 2010 1.6cr Fabia for nearly 18 months now and it is used mainly on motorways and A roads and has done 15,000 miles.  The economy I get is around mid 50s on motorways and between 50and 65mpg on A roads.  Like A Laws, I do find the idling rpm too high (it does eventually drop from 950rpm to 800rpm after 3 or 4 seconds once stationary) but this is a nuisance in slow moving traffic where the car wants to accelerate but I don't, necessitating rapid declutching.  I discussed the problem with my dealer, as the car is stil under warranty and I would like it fixed, but I was informed that Skoda have issued a bulletin as this is a known problem with the 1.6cr engine, it is due to the ECU software and is DPF related, and nothing can be done to resolve the issue.  Has anyone else come across this?

[A Laws]

Could it be then that the car was driven 'poorly' by the person before us and as such the computer has adjusted itself to their driving style?

 

Is it worth carrying out an ECU reset and starting afresh?  If so will it reset all the locking setting etc or will they remain?

Edited 24 August, 2014 by A Laws

[Gino4]

You would hope that the ECU would be constantly monitoring driving parameters and responding accordingly, rather than locking onto data accumulated 3 or 4 years back.  I will have to ask my dealer if an ECU reset is possible and what other settings may be lost.  I have not noticed any DPF cleaning operation in progress on my car.  I have experienced this before with a Seat Ibiza 1.2 TDI courtesy car loaned to me last year, and was quite alarmed that on pulling onto my driveway the cooling fan was buzzing away and there was quite a pungent aroma noticeable.  When I returned this vehicle, I said to the dealer that there seemed to be an overheating issue but he explained that it was simply the DPF cleaning cycle and quite normal. 

[A Laws]

Well its back at the dealership - However i'm waiting for the 'No faults found' comeback.  Having said that Skoda UK are also monitoring what the dealer diagnoses/ comes back with as the car is still with in the 30day/1000 mile exchange period.  I don't really want to change it but if they come back with nothing they leave me no option.

 

The 600 miles we've had it has averaged 40.4 MPG on routes that the VRS and Ibiza TDI averaged 51-55 so in my eyes there is something wrong somewhere.

 

Fingers crossed they find something and this can be easily resolved.

Edited 27 August, 2014 by A Laws

[A Laws]

Well the dealer has come back with no faults found and during test drives over the last 24 hours say they have averaged ~50 MPG.

 

As they can not find any fault they advise there are no grounds for an exchange and if we did want to pursue that avenue would offer us the book trade in value for it, which is 1.5K less than we paid for it 3 weeks ago.

 

A bit disheartened atm.  All I can hope is that the poor MPG we've seen was due to the car cleaning itself etc from possibly where the last owner didn't drive it on particularly long journeys, and things will get better.

[Phil-E]

Have you given it a proper run? As is have you let it warm up nicely then found a quiet road and taken it to the red line a few times?

 

Also are you driving it the same as the 1.9 TDIs you had previously?

 

The torque curve is different on this engine and it prefers to be reved slightly more and with pretty tall gearing meaning that if you change up too early you can labour the engine and use more fuel than needed.

 

Have you also done a proper fuel usage calculation or just going by the dash board?

 

Phil

[GeneralPurpose]

A Laws, you mention your have only had the car for 3 weeks. Sorry, but am going to plug again a very important point. I believe what you are describing is a classic case of 'not knowing the car' and this is leading to obtaining poor mpg. Witness the fact the garage obtained many more mpg's than you, although of course no two people may get the same mpgs and the routes will have varied to yours. While you may have an issue with the engine, dpf or brakes binding, it's unlikely. When this engine was released, masses of people were complaining of poor mpg, so much so that I undertook a study of 13 cars with this engine in. I followed the progress of these cars and drivers for around 15 months. That was unintentional, it was meant to last 6 months! Mostly these were Fabias, but some Golfs were included. The VW forum was also inundated with this same issue. I'm an ex-tech and engine design and development engineer. So I was interested to to get to the bottom of the issue. I visited several owners who were getting the worst mpg's and examined their cars for defects. I found none whatsoever except for one issue with a Golf. What I did find was a lack of understanding on how to drive this 1.6cr. Shorter stroke diesels like the 1.6cr require a different driving technique to diesels of old, especially when coupled to a high ratio gearbox like in the 1.6cr. Most were driving it in the traditional way using low revs and using the engines torque to get good mpg's and always using 5th gear from lowish speeds. But doing this, the reverse was happening as piston speed was being reduced too much and the engine then uses too much fuel and struggles. It may not sound as if it is struggling or that anything is wrong, but it is if you don't rev it sufficiently. It will also trigger too many regens, which you are getting, and is another indicator that it is maybe your driver technique that is wrong. Too many regens wastes lots of fuel and reduces your mpg's. Nearly all but one of the 13 cars in my study was being driven with far too few revs and this was the only thing responsible for the poor mpg's. I found one Golf that had a faulty ecu. This was replaced. All was good with that car afterwards. I'm not going into much detail or technical stuff here about the study (which was not wholly scientific) but it showed beyond doubt that driving technique is so important when using this engine. It cannot be driven like the older diesels. Absolutely ALL drivers reported a big improvement to their mpg's once I had instructed them on how to drive it. It was literally learning a new driving technique altogether for some of them. Many of these drivers had been driving for years and years and so were very experienced, yet couldn't fathom out what was wrong. But through some basic instruction and experimentation, the fuel economy came not only good but exceptional in many cases. All are now pleased and surprisingly, all obtain or exceed book figures. I'm sure this is all it is. Many in my study were reporting the issue just like you and were confident something was wrong with their cars. Of course, what I am saying could be all wrong concerning your situation. But I would doubt it. Just look at the number of posts on here about it and the number of people reporting the problem fixed by adopting a different driving technique. You should experiment with technique and I'm sure you will notice a difference. Don't use 4th too much in urban areas and don't use 5th gear under 55-60mph. It makes a difference. 5th gear is an overdrive and isn't needed all the time. It doesn't give best mpg's unless you are going above 55-60mph and preferably faster. Experiment! Good luck and don't be offended by any of what I am saying about driving technique. I'm sure you are very experienced as a driver. 

[A Laws]

Well upon picking it up the car seems different. Although they found no faults it picks up better with less hesitation. We always drive through the rev range not usually changing before 3.5k (and yes the car has had a good few clearout in the last few weeks)

 

Considering 'nothing' was found, and our driving technique hasn't changed, its now giving us 49 mpg, on a run where it was giving us 40.

 

I'm a bit bemused tbh - I don't know whether their testing has reset something or we had a bad batch of fuel. We'll adapt as we go to tune our driving style to the car but it feels like a totally different car since being picked up.

[Phil-E]

I wonder if they have actually done something? Maybe they have given it a software update or something... so although they didn't find anything wrong they updated it anyway. You would have thought they'd have told you that though if it was the case!

 

Phil

[GeneralPurpose]

That's splendid! I suspect the ecu has been reset. It's something that is done from time to time when customers report this issue even if no fault is found. It does however put the ecu into learning mode for 3k miles. It's only a basic learning function but it averages the engine paraments on all sensors for that amount of time and is aimed at optimising the power and fuel consumption to keep dpf emissions to a minimum. On the other hand nothing has been done and your fuel in the tank was just old and bad. But diesel doesn't go off in the same way petrol does, it takes a long time for that too happen. Perhaps your car was on the forecourt for ages before you bought it leading to the fuel going 'off'. Another thing, maybe you had excess water in the fuel filter and someone has drained it. Anyhoo, sounds like you are on the road to recovery. Keep posting please to tell how you are getting on with this issue. Thanks!