Hey All

My Octavia is coming up to needing a service in the next month or so ; so I'll see if that improves things somewhat - but to be fair, since my last service (oil + filters) and numerous parts I replaced as part of my Overboost solving saga (boost hoses, n75, MAP and MAF sensors, reverted back to stock from a remap, etc) I seem to be under the illusion that my fuel economy has plummetted.

Can anyone give me some ballpark figures of what their 110tdi or even 130tdi (give or take) nets them in miles on a full tank via mixed driving?

I recently replaced all my tyres for some fuel efficiency B Sportrac tyres which recieved good reviews, and everything else seems in good order.

However despite the instant trip computer guage hovering around 50 - 60 mpg on the motorway and 40mpg around town, it never feels like I am getting anywhere near these figures.

I spend £60 to fill him up, and on a commute of 15 miles a day averaging 40-60 mph I seem to recently be rinsing the whole tank dry in around 350 - 380 miles :-S

When I first got the car, I was almost certain through mixed driving I could get 470 odd miles from a tank !

After investing so much money into Otto the Octavia, I don't really want to let him go especially with only 57,000 on the clock, but I feel really bummed about my economy at the moment.

Does anyone have any advice as to what may be causing a sudden drop in fuel economy? (Performance etc is good - especially since following Lofty's Mr Muscle guide and sorting my overboost woes)

I do occassionally get a little nudge of overboost but subsequently taking it out for a good thrashing after seems to set things back to normal!

Edited 9 January, 201313 yr by MurphmanL

I used to get 450-500 miles out of a tank on my old 110tdi. Have you had the car checked for fault codes recently?

Not recently no, last time I did have two - one was the overboost classic one and the other was something about coolant - negative current against positive open or something like that...

Either way, the overboost one I solved and the negative current cooling thing went away on its own (seems an intermittent one) somtimes it would show up, others it would not !

Have you checked the timing with VCDS?

I normally expect around 600 miles per tank (fairly sensible driving). Certainly at half a tank of fuel indicated the trip computer will have just rolled over 300 miles. I do tend to refill the car up when there is about 1/4 of a tank left. I have to drive to work tomorrow so I can dig out a couple of receipts and do the sums if you like. My commute to work is 60ish miles each way so the car gets warms. My drive is a mixture of villages and rural A roads (good for 60, and a short section of dual carriageway), plus Weymouth and Salisbury! My car is 2001 110TDi with 207k on the clock, currently on winter tyres.

If your commute 15 miles each way, or total? If total, then then car will never get warm, so your figures seem low, but acceptable given the short distances you drive.

If you are still seeing an overboost fault, then try manually operating the actuator on the turbo again and see how smooth the movement really is, or even consider a second clean. Any boost leaks on the pipework? How clean is your EGR assembly?

cleaned up the EGR valve etc at the same time as Mr muscle-ing and did a good 2 hour cleaning with lots of pumping around 2 months ago - not sure how the carbon has built up quite so quickly.

I'm not overly knowledgable of car mechanics, the Mr Muscle treatment really pushed my confidence and that was with help!

The commute is 15 miles total, so 7.5 each way. When I think about it though my 1.4 Litre Nissan Note Petrol used to fill up on £40 of fuel and I'd get 330 miles so the octy isn't doing very well in my opinion.

AS I say I'm certain I used to get >500 miles mixed, suddenly it's as if it's literally drinking through the diesel , nothing seems too amiss though.

Guess I could ask my mechanic to look for a fuel leak / blockage maybe? :-S

Come to think about it, the fuel computer when filled up comes up with 505mi as the range.

By time I leave the forecourt and get onto the main road its down to 465mi and then slowly but surely depreciates unevenly until it's all gone by 370 miles or so!

Just a few days ago I put £20 in and it took the needle to just under half - trip said 165 mi , have driven a total of 60 miles and trip is now saying 80mi and it's close to setting off the fuel reserve light ! Not very good value for £20 fuel :(

Edited 9 January, 201313 yr by MurphmanL

How's your air filter looking? Mine was caked after only 8k this time round, dirty roads and wind kicking it up

Sounds daft but where abouts are you getting your fuel from ? My dad was running his superb on morrisons diesel and getting 350-400 miles to a tank he then tried shells standard diesel and now gets around 450 ish per tank

If it helps, I either use Waitrose fuel (95% of the time), and Esso (5%). The Waitrose I use (not sure if this applies to them all) is now badged up as Shell, but that only happened after a refit a month or so back.

I still think part of your issue is that a diesel isn't really ever going to offer amazing figures on such short trips, although if you have seen higher then there must be something amiss.

As Lofty said, check your air filter, and when was the fuel filter last changed (although that isn't really a reason for it to "drink" fuel).

I do a similarish (11 miles each way) commute on a route that can be sore on fuel, and get about 440 miles (Winter) to 480 miles (Summer) from a tank (pressure cutoff to low fuel light).

I've only ever done quite short commutes to work (each way, not round trip), down to about 5 miles now, used to be 6-7 I guess and I was always informed by the computer that I had 520 miles to go after a fill up. I figures I was getting a bit less, high 400s I think.

Of late I've been doing quite a few longer trips on a dual carriage way, and with a little careful driving I have seen several miles to go readings of about 600 after filling up.

I can do a hard motorway run, finishing with some fast A road of about 380 miles and still have a quarterish tank I think it is. When I roughly calc'd that last time I was seeing a bit over 500 miles, something close to the inidicated 520 I think.

She hasn't the miles of mbanes, I can only russle up a poxy 174k.

Tom

I do 60 way round trip each day 6 days with a 110Tdi and I run either BP or Shell depending which end of the journey the light pings on at which then needs a 48litre ish fill... Last few fill ups looking at the Fuel log app gave as follows...

48litre fill gave 544 Miles... 51.52mpg

47litre fill gave 513 miles...49.62 mpg

46.80litre fill gave 505 miles 49.06mpg

46.89lites fill gave 567 miles 54.97mpg

48.65litres gave 595 miles 55.60mpg

36.91 litres gave 320 miles 56.15mpg...

Cold weather and the MPG goes to **** I find... Anyone ran with the grille half covered to up the engine temps? Or used one of them Heko winter covers?

Just checking on Parkers it says that we have a 55L tank, that's 12 gallons. It also says that we get 53 mpg.

So in a utopian world of driving at the pefect constant speed, correct temp, no extra load on the engine, no stop starts, no hills etc etc we should get 636 miles.

Tom

So in a utopian world of driving at the pefect constant speed, correct temp, no extra load on the engine, no stop starts, no hills etc etc we should get 636 miles.

Sure I could do that

I used to get 47mpg out of my 110 estate. Occasionally saw over 550 on a tankful but only on long journeys. Usually around the 450-500 mark. That was running standard, over nine years from new.

I usually get about 550 miles from full to light on, but the bulk of my weekly mileage is driving to Shropshire on Monday morning and back to the North East on Thursday afternoon, with a normal 15 minute commute down country roads in between. Normally works out at about 53 mpg.

I have a L&K 110, running on WVO. I get 450-600 from a tank. At the moment its nearer the 450-500 range. Its winter... de-misters, heater, climate control, lights, wipers, heated seats, mirrors, fog lights, they all get used more and reduce your MPG. Maybe try turning everything off and take it for a spin. This might improve things. I always found my car improves after a service, is yours due? Check your tyre pressures, this makes a big difference, and check your under engine cover isnt doing a good impression of an air brake underneath. Also, my car is best on A roads behind lorries, get on a dual carriageway and its crap. Best MPG is 40-50MPH, in every 1.9tdi I have ever driven! 90, 105, 110, 130 and 150!!! 6th gear helps a little on some models.

My old 90 used to touch 700 a tank driving like a grandad. But then the turbo and EGR used to clog up quicker than a fat blokes arteries.

After bigger nozzles, remap, straight through exhaust, bigger boost pipes, and some stream lining, i can now get near 900 miles from my 90 bhp motor, but for that i drove to chichester and back from blairgowrie in one go, but had to refuel near glasgow on way home, 55 mph all the way and 76mpg

55mph = tooooo boring. Drive faster and enjoy life

You mention you've had intermittent codes popping up regarding the coolant signals - Do you know if the Coolant temperature sensor has been changed on your octy? It's quite a common fault, and VAG released a revised part at some point to fix the issue.

The sensor tells the ecu what temperature the engine coolant is at to enable the ecu to adjust fuelling accordingly, and so if that's on it's way out the computer will be thinking the engine is constantly cold and over fuelling, hence wasting your fuel.

I'm afraid i don't have a part number for the revised part but they're relatively inexpensive, and it's the green sensor you'd be looking for that replaced the originally fitted (black) sensor. There's plenty of posts about the issue on here.

I'd give it another scan as a starting point anyway!

Hi All

Many thanks for all replies - something is definitely amiss, I'm not driving it particularly hastily and I recently burned thorugh £20 worth of fuel in 105 miles (60 of which motorway at 70mph) , recently been to BP and filled up with £40 worth to see if perhaps the fuel I am using isn't too good.

Trip CPU showed 300mi on £40 and within 15 miles driving now shows 265mi :( but alas I did have the heating and seats on today due to the snow.

No idea how you guys are hitting 600+ miles from a tank , are you actually pressing the accelerator? - when I first got the octy though I was sure I could get a good 470-520mi from a tank ! Now , I'm always at the pumps even though I've invested loads into the car over the past year!!

My service is due end of this month / early next along with MOT so I think I'm going to have a K&N air filter added and perhaps replace the coolant temperature sensor and see if that helps !!

Edited 14 January, 201313 yr by MurphmanL

58mpg. 47 mile each way a road commute.

Never above 2000rpm except a couple of times to clear out any soot.

90bhp classic.

250k miles.

Approx 700 miles to a ful full tank.

Did you know you can get an extra 7 litres in by pressing the air release valve inside the filler neck.

Just don't fill up, drive 2 miles and leave your car in the sun all day....

I have kept a chart of actual fuel consumption for the last seven years. Most of that time it has been short journeys with the occasional long motorway blast. In the winter the water is usually up to 90 at the end of the trip but I doubt that the oil has reached proper temperature.

From the graphs, the average winter fuel consumption is 41.55 mpg and the average summer consumption is 51.75

i routinely get 700+mls from a tank, best iv managed 760 from brimmed to as close to dry as i dared..

but thats mostly a 25mile each way commute on a single carriage road normally stuck behind a couple of lorries..

Approx 700 miles to a ful full tank.

Did you know you can get an extra 7 litres in by pressing the air release valve inside the filler neck.

Just don't fill up, drive 2 miles and leave your car in the sun all day....

???????