Disappointing fuel economy, Octavia II

[Rabbitboy]

Hi,

 

I recently bought a late 2009 Octavia II 1.6 TDi and am finding that I’m consistently getting a disappointing 39mpg.  This is compared to the 55mpg I was getting with my 2000 Octavia I 1.9 TDi.  I’m driving mostly on country roads, no traffic.  Can anyone tell me if I should expect more, and if so what a garage should be looking at?

 

Thanks

[langers2k]

I'd expect more if it's getting up to temperature, what length of journey are you doing?

 

How are you measuring the fuel consumption?

 

Have you checked the obvious causes like binding brakes, tyre pressures and that it's been serviced recently?

[Rabbitboy]

I'd expect more too.  Well, it's good to know I'm not alone.

 

It had had a service before I bought it, but from a small garage whose reputation I know nothing about.  So, yeah, I'll need to get it serviced again myself I suppose.  

Tyre pressures okay.  

Brake binding I'll get checked out too.  But wouldn't I notice that while driving?

 

Cheers

[Rabbitboy]

Oh, and I'm measuring the consumption by filling the tank and noting the miles covered.  Same as I was doing with the old car.

[Ootohere]

Apples and pears really with the great engine you had and the Euro 5 emission 1.6 TDI CR that VW even had to fit defeat devices to to be cheating the emissions testing.

 

Has your car had The Fix, so new engine management and a flow device fitted?

http://skoda.co.uk/dieselinfo

 

[Rabbitboy]

Thanks.  I checked, it hasn't had this fix.

 

So I suppose I just need to get the car serviced at a Skoda garage and see...

[Ootohere]

If at a Skoda Dealership you need to be sure they know you are not having the Fix. 

 Made very clear if by some error they do it they will get sued.

 

Tape over the OBD port.

[Rabbitboy]

Erm... help me out here!  You're saying I SHOULDN'T have this particular Service Action done?...

[sakta]

17 minutes ago, Rabbitboy said:

Erm... help me out here!  You're saying I SHOULDN'T have this particular Service Action done?...

Yes. The new software may ruin economy and reports say worse performance slightly. But this varies, some people complain, some say it feels the same.

 

Either way, the higher emissions wont affect you!   better off without it

[pikpilot]

Don't get the fix done. Of those that have the fix 1-2 years ago there seems be a rising number of 1.6 engines that have had the dpf fill up completely or disintegrate internally due to failed regenerations.

The result is that the excess of fuel used for regeneration goes into the engine oil which in-turn can cause the engine to burn the oil/fuel mixture in an uncontrollable runaway which destroys the engine.

[Rabbitboy]

Good to know, thanks!

 

So do you think I should bother paying the premium to have the car serviced at a Skoda garage, as opposed to a reputable local garage?  Or maybe just once, having recently bought the car?

[langers2k]

Checking the brakes for binding is easy enough, check the temperature of the alloys after a normal drive. I'd suggest using the back of your hand and if one is much hotter than others it could have a problem.

 

If the tracking is massively out that might also cause issues.

 

What length of drive are you typically doing?

 

I guess you could have is scanned for fault codes using VCDS or similar. Not sure if anything will show up.

[Rabbitboy]

Thanks.  I don't have alloys, but will get the brakes checked out anyway.  I'm pretty sure the tracking is fine.  I typically do 4 mile one-way journeys, sometimes 15 and 30 mile trips, all country roads and motorways.

 

What's your view on using a Skoda dealership for the work/service, over a good local garage?

[langers2k]

On a 9 year old car I doubt it makes much difference as you're well out of warranty and unlikely to receive any good will from Skoda towards any failures. If the local garage is competent, it should be perfectly fine and cheaper to use them. Just make sure you're sticking to the service schedule and personally, I'd try and stick to genuine parts.

 

I think it's probably the 4 mile journey that's causing your low economy as modern diesels take a while to warm up and won't achieve full efficiency until they have.

 

It'll also be fitted with a DPF (diesel particulate filter) which catches soot from the engine and then is burnt off during a DPF regeneration. On such short journeys you might find it struggles to get hot enough to regen so you may need to take longer journeys occasionally to keep the DPF in good health. How many miles has the car done?

 

I hate to say it but a petrol may have been a better choice given the usage you've described...

[Rabbitboy]

I see.  I guess I just assumed that, if there were no technical issues with the car, it would give me at least the same fuel economy as the older Octavia for the same kind of use.  Checking the real mpg figures online had reassured me of that.

The car's done 110,000 miles, by the way.

Cheers

[FatblokeVRS]

We had poor MPG with the VRS CR when we got it a few years back. We were getting around 400 miles to a tank of diesel and the rear tyres had the sawtoothing issue.

 

Had it in to the dealer twice for tracking. They didn't do it right as we still only got 400 miles per tank.

 

Took it in to a specialist for 4 wheel alignment. Immediately jumped up to 480 - 500 miles per tank.

 

We get it checked and adjusted every so often and still getting 480 - 500 miles per tank and no sawtoothing of the rear wheels.

 

Even with a remap, I have managed 54MPG (average over the tankful) but normally mid to high 40's.

 

I change the oil and filter every 5, 000 miles also.

 

 

 

Edited 24 October, 2018 by FatblokeVRS

[andreasw]

I'm also not happy with my consumption. Don't know how to convert l/mil but it's 0,71L/Mil. That's 39mpg imperial. Sometimes it feels like the car runs much leaner. And sometimes it runs more thirsty. Haven't worked out how it works yet. Need to check my dipstick so see if the oil level is rising.

[langers2k]

I watched the temperatures on my 2.0l TDi CR140 this morning on country roads. With an ambient temperature of ~13'C and speeds between 50-60 mph due to traffic it showed:

- after 4 miles, the coolant was ~65'C and oil less than 50'C (minimum to show on the cluster)

- after 10 miles, the coolant was ~90'C and the oil ~70'C

- after 15 miles, the oil was in the mid to high 80's and I considered it warmed up

 

I'd expect the 1.6l to be pretty similar for warm up time and possibly explain your fuel economy.

 

It might be worth checking the oil ash level in the DPF as at 110,000 miles, it could be coming up for replacement depending how it's previously been driven. A cheap OBD adaptor and the VAG DPF app should be fine.

[J.R.]

Like you I had an early 1.9 110 TDi (2002) and had excellent economy, 55-65mpg, then I changed to a 2006 1.9 105 TDi (BKC engine) and was delighted to see that I was getting even better economy, 68mpg overall and indeed the first tank I ran to dry to check and got 800 miles, however on the second tank despite my dash display showing an average of 65mpg I had to refill at 620 miles and when I calculated the consumption from how many litres I put in it was around 50mpg.

 

Now I am an old fart with a poor memory, perhaps I jumbled the figures on the way home, perhaps it was 720 miles and I had reset the trip so could not see, perhaps I had not correctly brimmed the tank the time before, lots of perhaps but the way this tankfull is descending its looking the same way.

 

And to my great shame despite doing 140000 miles in the older vehicle I dont think that I ever cross checked the indicated consumption against the fill ups and mileage.

 

I will know at the next fill up if the fuel computer is over optimistic, trouble is if it is then the last one will have been, its as much a comparator as anything else and I probably wont make a correction via VCDS, I can afford the fuel these days not like in the past.

[pikpilot]

For a four miles one way journey in winter I get around 40 mpg on the display. In summer this is around 55 mpg. 

 

The high efficiency diesel engines take quite a while to warm up and this is reflected in low mpg for short trips in cold weather.

For a long non motorway drive in summer I get 60+ mpg and continuous fast motorway driving  gives around 55 mpg winter or summer. Dropping the average speed by 10 mph gives about another 5 mpg.

This is for the same engine as yours.

[andreasw]

6 hours ago, langers2k said:

I watched the temperatures on my 2.0l TDi CR140 this morning on country roads. With an ambient temperature of ~13'C and speeds between 50-60 mph due to traffic it showed:

- after 4 miles, the coolant was ~65'C and oil less than 50'C (minimum to show on the cluster)

- after 10 miles, the coolant was ~90'C and the oil ~70'C

- after 15 miles, the oil was in the mid to high 80's and I considered it warmed up

 

I'd expect the 1.6l to be pretty similar for warm up time and possibly explain your fuel economy.

 

It might be worth checking the oil ash level in the DPF as at 110,000 miles, it could be coming up for replacement depending how it's previously been driven. A cheap OBD adaptor and the VAG DPF app should be fine.

Interesting, can I check with VCDS? I have the OBDeleven, and I should be able to see if vcds supports it!

[langers2k]

4 minutes ago, andreasw said:

Interesting, can I check with VCDS? I have the OBDeleven, and I should be able to see if vcds supports it!

 

VCDS certainly can, I don't know about OBDeleven. If you can access the measuring blocks, look for oil ash volume or something similar.

[Jevpls]

Well, if the usual journey is 4 miles only then what do you expect? You get higher mpg only when the engine has been warmed up but it doesn't in 4 miles (OK, it might warm up but only in hot summer).

[andreasw]

I have 19 miles to work. So it's getting enough heat still only getting 39mpg.

[J.R.]

Mine reaches operating temp in exactly 4 miles, some warmth from the heater after 2.4 miles, stat opened by 4 miles.

 

I can however be up to 70mpg inside 3 miles, the visit to my friend in the next village, slightly downhill, after the return journey it will be maybe 65mpg, these are all from the fuel computer which I suspect of being optimistic but my MK1 Octavia was just as good.

 

It all depends on driving conditions of course, locally there is little or no traffic, no stop and go and low speed limits, a return trip to town which is a total of 3.4 miles and some stop start will return 55-60mpg as did the previous Octavia.

 

Whilst i know that the engine is  not fully efficient until warmed up, oil resistance etc I have always thought that the major advantage of diesel compared to petrol was during the warm up cycle, a petrol engine needs a richer mixture until up to temperature as those of us who are old enough to remember manual chokes will know well whereas a diesel once the glowplugs are turned off (or even earlier on modern post combustion glow systems) is self sustaining compression ignition without any extra enrichment.

 

I have tried this at the 400m mark from my home, the fuel computer starts at 200m, from a cold start I can be in 5th doing 50kph and look at the instantaneous fuel consumption and its barely any lower than the same spot, same direction, same speed after the vehicle has run for hours.