Fuel Economy on Octavia 1.9TDi is waaaay down

[Phil_P]

I've still only done a few hundred miles in my brand new 1.9TDI, but I'm just managing to squeeze 50.0 out of it by coasting down hills and pottering along with a light right foot (occasionally I give it some welly going up a hill just to check the turbo is still there ).

Given it's not run in yet and the weather is cold, I guess that's about right. I'm hoping for 55-60 once things improve with careful driving and a solid return of above 50 when SWMBO drives it with her leaden right foot (I swear she uses the go peddle as a foot rest!)

[Raglits]

(I swear she uses the go peddle as a foot rest!)

That could be where I'm going wrong... Only got 42-44 mpg out of the Saab I had and colleagues were getting 50ish

[octavia007]

Think I agree JohnGW...think weather has affected things more than I thought... the anti-waxing additives in diesel issue is quite interesting but on a long run from the South Coast to Cambridge (quite warm today)...still gotta unstable idle (850 - 900 rpm on 90degrees C),....still got horrid "lag" on acceleration...(couldn't pull the skin off a rice puddin').....on driving half the distance between 80 - 90 and then rest of the way driving like a cautious nun (55-60mph tops takin it really steady and coasting where I could) - still returning cr@p mileage compared to my last skoda.

The way I drove today - I should have at least evened out and averaged 50mpg..I ragged the last skoda I had - and even putting my foot down returned 50mpg on average.

Garage (AGAIN) this Friday....I'll feedback after that...that's assuming the garage actually employs mechanics and not "fitters" - and can thoroughly check different avenues to close off potential faults!!

[Stormchaser]

Mines down on MPG too in this weather.Now doing 45-50 where usually between 55-60 so its no suprise really.

[octavia007]

Went to the dealers last Friday, and took a technician in the car with me so he could see what I was trying to describe over the phone. To be fair - he was very helpful...and Skoda Octavia owner himself.

We went for a drive and I said the acceleration was v poor in 3rd 4 and 5th gears. We then disconnected the MAF sensor and drove some more. disconnecting the MAF puts the ECU in "default" mode. There was no real difference in performance, however he said that there would be notable differences if the MAF was faulty. Logically - this appears illogical! However I took his word, we went back to the garage and linked the car up to the £15K bit of kit (known as VAS...not VAGCOM) and he went through all the details. No fault (other than the disconnection) was showing for the MAF. I asked about the coolant and fuel temp sensors - but they seemd OK (but to check was a tricky job.

The readings (below) show (at normal optimum running temperature) that the status was in the prescribed range of settings:

Coolant Temp: 81.9C (specific value [or range] >75C)

Engine Speed (at idle): 810 rpm (allowable range 770-870rpm)

Specified Exhaust Gas Recirculation (EGR) 240 mg/H (allowable range 200 to 280 mg/H)

Current EGR: 225mg/H (allowable range 180 to 300 mg/H)

EGR duty cylinder: 43% (allowable range 20 - 90%)

Fuel temp: 69.3C (allowable range 20 - 95C)

Current air mass: 255 mg/H (allowable range 170 to 300 mg/H)

So I'm completely bewildered! I asked the guy why I was still getting poor MPG. The reasons he offered were:

ECU recalls/ memorises (to a certain extent driving styles)...so as I'm the 2nd driver, the previous driver's style could be "lingering" in the ECU. He said I should drive it as I would drive my last skoda. He also said I should give th car another 10k to seems how things "bed in" and to see if there are any changes. He said although the estate (which I have) is marginally heavier, there shouldn't be that much difference in performance. He said - sometimes diesel engines (mine's a BXE engine used from 07 onwards) should be better than the previous MkII Octavia I had (on a 55 reg). He also said that the immediate MPG signal on the dash was not nearly as accurate as the average MPG reading - and to not pay too much attention to it. I had been paying a lot of attention to it as the readings until cruising in 4th or 5th are very, very low (between 6mpg and 27mpg).

With warmer weather still upon us - I'm still unsure about the diagnosis...but I'm kind of lost as to what to do next! Was thinking of installing a TDI tuning chip (about £30 for an OK one on E-bay) as this both improves MPG by a few miles and boosts performance by about 10-20bhp. However - I'd need to be sure it wouldn't harn the engine in the long run. Do you know if these tuning chips knack the engine? I used to drive my previous Skoda quite hard and still get 600 miles to a tank and get 50+ mpg!

Just really hoping I haven't got a "dud one"...but judging by the diagnostics results (which only showed to glow plugs had blown - which will be replaced Monday) - there isn't anything wrong with it. In spite of it being noisier than my last one, poorer performance than the last one and using a shedload more fuel than the last one!!

[menacer]

Had my 1.9 TDi (mk2 105 bhp) since the 22nd of December and im managing exactly on the dot 50mpg and thats driving just normally, not trying TOO much, i hope it goes up a little in the summer months!

[durhamfisher]

You could speed up the reset process by following this thread:

http://briskoda.net/forums/topic/146724-re-map-not-feeling-like-it-used-to-read-on/

Although you dont have a remap, it should work for resetting the driving style "memory" from the previous owner.

Dont by a £30 tuning chip from ebay, loads of posts on here on why you shouldnt.

Dont see the logic around the MAF disconnection, surely if it was working OK and you disconnect it, you should see a difference in performance?

Did you discuss the starting issues with the garage?

[octavia007]

Totally agree stacon. Where is the logic in disconnecting MAF? The performance is not nearly as good as the last MkII Octavia I had and yet it pulls OK(ish) on accelerating, and doesn't seem to be misfiring or anything.

Nothing really changed with the MAF disconnected though...maybe it takes a few miles to drop into "default" mode before performance drops off...and we only drove a mile or two.

I'll stay clear of tuning chips. Have read the low down. They aint great by the looks of it.

Really flummoxed still. Why should I still be getting 520 miles (driving like ya Nan) to full tank when in the past I'd be getting 600+ miles on the 2005 MkII (driving hard)? doesn't make sense!! Also - the engine seems to run a little noisier than the last one (although I'm possibly just splitting hairs here). Maybe time to try and see another dealer for second opinion? Any technicians out there got any ideas?

Did the reset on driving style yesterday. Driving to Bristol tomorrow - so I shall see how the mpg goes on a long run then and feedback.

The car (law of the s0d) starts fine now - so I put that down to cold weather and perhaps the fact that a couple of the glow plugs were faulty (changed today).

[Stormchaser]

Mines a 2006 Octavia 1.9TDi and i got the BXE engine in mine too.My MPG is starting to rise also now but i never look at the instant MPG reading on display i look at the MPG 2 reading which is as the mechanic stated a more realistic reading.The other day in the cold weather i was town driving and I was getting an instant MPG reading of 38MPG :'( and thought oh my god what the hell was wrong bjut looking at MPG 2 reading it was saying 53 MPG.So i wouldn,t take the instant as gospel.

Another suggestion on here is to do an ECU reset where you disconnect the battery for 2 hours then reconnect start engine and let it idle for 10 mins without touching the throttle and switch off.Then after drive as you would normally drive.I done this and now its much better and far more responsive and great MPG figures now but obviously i don,t hang around so the ECU logs my driving style.

Also i too have noticed far more engine clatter since but i put it down to the weather and slow engine heating.

Good luck and hope your MPG gets better.Keep us posted.

[redlemon]

i recently bought a 58 Octavia estate 105PD DSG with 8.5K on the clock, to replace a B4 Passat TDI 90.

have to say, i'm somewhat disappointed with the fuel consumption of the octavia. 46.5 average on the MFD, but a real life 42.3 measured brim to brim, and that's driven gently, mostly round town, but with some motorway. MPG2 has never got to 50. my old passat would have done an easy (genuine) 50 driven any old how.

we also have a B5.5 passat TDI 130 which was a bit juicy when new, but is now fairly frugal at 80K odd. maybe the octy will loosen up? i don't really want to wait 60 thousand miles though.

Edited 30 January, 2010 by redlemon

[Avalon]

You're still running it in at 8.5k and look at the spec's, the 105 DSG, it's supposed to return 47mpg combined off the top of my head, running it round town with a bit of motorway will give a lot closer to the urban figure so it's more or less about where i'd expect it to be. Diesel only makes financial sense if you do a minimum of 2k a month, other than that it costs you more than an equivalent petrol to purchase and run.

[redlemon]

You're still running it in at 8.5k and look at the spec's, the 105 DSG, it's supposed to return 47mpg combined off the top of my head, running it round town with a bit of motorway will give a lot closer to the urban figure so it's more or less about where i'd expect it to be. Diesel only makes financial sense if you do a minimum of 2k a month, other than that it costs you more than an equivalent petrol to purchase and run.

i agree about the running in bit. it still feels like a new car, and i remember complaining to the vw dealer about the poor economy at our passat's first service (17K), and it's pretty good now.

however, others claim to get 50+mpg a few hundred miles from new. i do wonder sometimes if they are referring to what's indicated on the MAF or what's gone from the tank?

the octavia is mostly used for short journeys, but i have a longer one next week, so i'll see how it goes.

Edited 30 January, 2010 by redlemon

[Browny_37]

I usually only get around 360-400miles if im lucky around town, but im running larger wheels/tyres around 30mm wider than the usual culprits.

I've once seen 540miles to a tank, giving it some beans on one stretch upto Yarmouth. Then poodling around town at low speeds and back home at around 55-65mph.

I've often wondered is it the MAF or Lambda Sensor that could be the cause?

Could people state there mileage's aswell as there mpg?

Maybe a table could be built to represent everyones mpg figures (brim to brim & trip computer)

[dsr]

I have a 2.0 TDI 103KW and I get over 650 miles from a tank brim to brim on my daily 200+ mile commute (typically I calculate the MPG and it's 53-56mpg depending on weather, my mood and if there's an X month etc.) - yes I know it's a stupid amount of miles :(

I have kept a full record of all the costs associated with the car since I bought it 16 months ago and it's running average MPG to date is 47.80mpg. I've only recently started doing the long trips and they won't go on for that much longer - thankfully - I'm spending 20 hours a week in the car and I'm fed up with it.

D

[halfmanhalfbiker]

ive had my octavia 1.9 for 6 yrs and done nearly 140,000 miles and always had really good fuel econ. my journey to work is 45 miles of varied conditions including quite a lot of slow traffic and i have always managed to average over 60mpg. even driving really hard flat out only ever edged down under 50mpg. while practicing some HyperMiling techniques i was managed 72mpg!

but now i have an EPG light on and after replacing the fuel temp sensor and the cabling have finally come to the conclusion that the ECU needs reconditioning/replacing. this problem has coincided with poor idle and poor fuel econ. now im lucky to get over 45mpg on my normal commute :-(

apparently the EPG only lights up and shows a fault if the temp being recieved is outside normal params. so if the ECU thinks that the temp its getting is normal then it will obey the reading even if it is not real and not actually coming from the sensor. so in my case the temp sensor warning goes on and off. sometimes the EPG light can be off for a few days - but the car still runs poorly at the start and returns poor mpg. basically the car is running at the default temp and so is only correct for a very small portion of the journey.

now i have to find a way of replacing the ECU cheaply...has anyone heard of http://www.the-ecu-doctor.co.uk/???

[sniper29a]

I recently bought Octavia II 2.0TDi 103kW - I was slightly shocked by fuel economy :-D It is like my Subaru Impreza, while driving at 160kmh.

 

I get fuel economy about 3l/100km at "shopping" revs (about 1500-1750)

 

Average is about 5.6l/100km up to 2500 revs - EU highways at about 130kmh

 

Once, you start to feed the horses - average 20l/100km, it is like a Subaru :-D

 

My old Fabia 1.4TDi 59kW used to have about 6.5l/100 at 150kmh @3500 revs