MPG drop

[Marnit]

Hi Everyone, this is my first post on here so please be patient . I have had my  2009 Octavia 1.9pd for a year now and

it has been great and is used for all sorts of tasks. I carry out my own spanner work and have

fitted a Valeo single mass kit as well as normal service work but my issue is will MPG. Until recently I could get 50 mpg with local driving and on a run 60 plus however since replacing the timing belt this has dropped of a fair bit.

The belt was fitted using the correct tools (fully inserted) and then checked on vag com which

gave a reading of -1.5kw the car now pulls really well, better than before the belt, I reset to 0.0kw and the power dropped off so it

is now set at -1kw this gives decent power but I have lost at least 5mpg. Sadly I couldn't check the torsion value with the old

belt so I don't know where it was set.

There is no smoke now but there was before, the only issue is the poorer MPG

 

Any ideas folks ? 

[Anddenton]

5mpg could simply be a result of the colder weather at this time of year. Mine has dropped off around 15% over the last month due to the cooling weather.

[marcusthehat]

yesterday was about 1 or 2 deg C. here in NI, our first proper winters day, I was noticably back on mpg's, by at least 5mpg, despite doing my regular Sat run over the mountain to visit my mother.

Over 5 years/90,000 miles this is what I have become accustomed to.

m

Edited 13 December, 2015 by dieseldogg

[jong123]

As 

Marnit +1

[Marnit]

That is interesting, may just have to wait for warmer weather then, thing is I only noticed the change after the new cam belt but I guess

that also coincided with the change in the weather. 

I have definitely changed something though as it feel like I now have  extra 20 tourque, it just feels more crisp if that makes sense.

By the way it is high millage for the year at 122 k 

[Gazman]

I put my winter tyres on last week and driving at 3 am this morning on a 25 mile run i was getting 34 mpg with the outside temp showing 8 degrees, was pouring down too and I was on un-lit roads, it's just the time of year..

[Greybeard]

That is interesting, may just have to wait for warmer weather then, thing is I only noticed the change after the new cam belt but I guess

that also coincided with the change in the weather. 

I have definitely changed something though as it feel like I now have  extra 20 tourque, it just feels more crisp if that makes sense.

By the way it is high millage for the year at 122 k 

Diesel's love to run on cool moist air. Had my Fabia vRS for 7 years, the PD130 in that always gave bonus MPG in summer but less grunt, come the Autumn weeks the fuel consumption would rise about 5mpg as per posts above but the crisper, torquier delivery was compensation for that! The difference was always noticeable as you describe, made those dry frosty February days well worth looking forward to.

 

Enjoy!

[Marnit]

Many thanks all for your thoughts I will have to see what happens when the sun shines again .

The only thing is that it's not really that cold here yet and it was a very sudden change in performance ie the day 

I changed the cam belt.

I do wonder if maybe it was incorrect before with low power and fuel consumption and now it's as it should be ?

Incidently what torsion setting has been found to work best ? I know the recommendation is 0.0kw but mine ran quite poor

at that setting. 

[seriesdriver]

I notice a slight drop November time when they start supplying the garages with winter diesel  as it is not quite as dieselly as summer fuel..

[Marnit]

Hadn't even thought of that tbh , there is more to this than meets the eye ..............

[silver1011]

Another vote for winter diesel here too...

 

https://en.wikipedia.org/wiki/Winter_diesel_fuel

[Jevpls]

 

Strangely, MPG improves again slightly as soon as the winter tyres go on. Probably because they go from 205s to 195s, but never could work out why.

 

 

Less grip area might be the cause. Might not as well. Tyres are different. Even 2 different summer tyres can bring different results.

 

About MPG. For me there is actually not much difference if we talk about greater distances. There is if we talk about short yourneys. The engine takes longer time to warm up and until that it consumes more.

[pipsyp]

Yep its winter blend diesel...gather it has to be altered so that cars still run properly during the colder weather...not entirely sure why though.

Oddly I think after a few tanks the car does begin to adjust to it though....I was only getting low 40's in my Golf GTD having been surprised to see low mid 50's with very few miles on the clock late Sept....it now averages about 46/47mpg pn a run which as others have suggested circa 5mpg down on its usual figures for similar runs.

[silver1011]

It's all explained in the Wiki link posted earlier, diesel can 'wax' in extreme temperatures.

[Jevpls]

No extreme temperatures are needed. So called "summer diesel" gets thick at approx. -12 degrees ©. Then it's not flowing through the pipes and the car doesn't run.

Special additives are added to prevent such situation. There should be some notes on the fuel stations about thickening temperature of certain diesel (-25, -32 or so). Probably in UK these temperatures aren't that low but I hope you understood the main idea.

[seriesdriver]

Whoever in charge who decides these things says winter diesel will be supplied between November and March.

[silver1011]

No extreme temperatures are needed. So called "summer diesel" gets thick at approx. -12 degrees ©. Then it's not flowing through the pipes and the car doesn't run.

Special additives are added to prevent such situation. There should be some notes on the fuel stations about thickening temperature of certain diesel (-25, -32 or so). Probably in UK these temperatures aren't that low but I hope you understood the main idea.

 

-12 is pretty extreme here in the UK 

[Phil-E]

I've noticed a drop in the MPG of late too with the same engine.

 

The average on the trip has dropped to 47.1 now.

 

I also have winter tyres fitted which seems to have made a slight difference as they have a lower fuel economy rating than my summer tyres.

 

Did a run down to Nottingham over the weekend and it seemed to be lower than usual. I would usually get at least 50mpg but just managed to get 47mpg. It was peeing down with rain too.

 

I also managed an abysmal 33mpg earlier today... but that was town runs and some A/B roads with the discovery of using Sport mode and holding the brake with my left foot to set off from a standing start... the gear changes are like I've never experienced before in this car! Oops!

 

On the subject of winter diesel and waxing... I once drove to Germany to a ski resort in our old Peugeot 306 1.9D. It had a full tank of 75/25 veg oil/diesel mix. With temperatures of around -20c overnight it started fine on a morning just with a few extra turns of the engine but it started and ran fine!

Edited 15 December, 2015 by Phil-E

[Jevpls]

Maybe that diesel was with some additives. I doubt that you had driven to Germany without refueling.

Like 2-3 years ago in the beginning of the winter my brother filled the fuel tank. He looked for some note proving that it's winter diesel but didn't find one, so he came to conclusion that it's obviously the one. That night was cold (approx. -20) and the next morning he wasn't able to start the car. The fuel was more like wax than a liquid. So, in the afternoon it was warmer and we took 2 hair dryers and after at least one hour of work and few unsuccesful attempt to start the car, it finally started. The original battery was almost empty while trying. Good that had another car to borrow battery from.

 

So, the summary: you won't die from that but it's a very unpleasant situation. Some time ago diesel drivers used to add some petrol but modern diesels aren't the ones to like that.

[Phil-E]

It will have been winter diesel yes.

 

And yes I can drive from York to Germany via Dover on less than one tank. Last trip we did 677 miles (1089kms) before refuelling and had driven into Dusseldorf then down to the Mosel. This was in the Octavia

 

The Peugeot 306 also had a bigger tank (60 litres vs 55 in the Octavia) so if you drove steady you could get really big ranges out of the tank.

 

Phil

Edited 15 December, 2015 by Phil-E

[pipsyp]

It's all explained in the Wiki link posted earlier, diesel can 'wax' in extreme temperatures.

Cheers Silver I hadnt read up on that. I did expect for diesel fuel to likely be more effected by lower temps than petrol as I guess its quite a bit more viscous.

[Metblackrat]

The winter diesel additive is good old petrol.

[Jevpls]

The winter diesel additive is good old petrol.

 

Actually it isn't. It used to be in older diesels but nowadays these modern diesels are quite sensitive to petrol. I wouldn't risk doing that.

 

By the way, about summer/winter diesel. I know that there is some EU regulation that allows to add like 5% of biodiesel to regular diesel in summertime (in Latvia it's not being done. I've heard that sellers somehow do not like it. Maybe it's being done in UK, who knows). This biodiesel is more sensitive to cold weather and in the wintertime it shouldn't be used at all (even that regulation allows that).

[skodacarman]

Your motor will run better on cool wet air, due to natural 'charge cooling'.

[Aspman]

Winter derv does drop it a bit.

 

-12 isn't so uncommon up here.

 

Also if the air is colder it's a bit denser and the engine will get a bit more oxygen per 'sook' and it'll put that little but more fuel in.

So your engine is just a little bit more powerful in winter.