High fuel consumption on 1.4TDi

[cardaft]

Right, i dont know if im just being stupid about this so please bear with me

My car seems to be using loads of fuel, its currently on 150 miles from full and its already down to the half mark, i never get less than 200 miles by this point.

It probably sounds normal and its just like being in my 1.0 fuel consumption wise, but im sure there must be something wrong somewhere.

The acceleration is how it should be, its driving fine but using quite a lot of fuel.

So im puzzled, ive had a quick look under the car for leaks but nothing.

Could it just be down to the cold weather? i doubt it would effect it this much, it didnt last year anyhow.

Ive not change my driving style or been driving faster than usual either.

When i filled it up, the tank before it did 55.5MPG, then after filling up within 5 miles the needle was already off full!

Then i got 47 MPG and it keeps giving me about the same. I know 47 still isnt bad but for my small disel its not right im sure.

On long runs now i get about 56 - 60 MPG, where as before i used to average that and get 68-72MPG on a good run.

Something is wrong

Have any TDI owners had this, or are getting lower than average MPG since its been a bit colder?

What should i do about it? Is there anything i can check, get checked or something to try and improve it?

Cheers, Chris

 

[sssstew]

a noticable drop is normal, im down a few mpg as well. but the amount your experiencing does seem a little high. do a long run to confirm.

 

[ChrisGTL]

How does your air filter look?

All your tires inflated?

 

[al_b22]

Sounds normal to me. Im getting around 45mpg on my 1.4TDI. It may improve once its run in a bit. Not even got to 1000 miles yet.

The cold weather dont help cause it takes a long time to warm up, so its not running as efficient as it could at this time of year.

 

[cardaft]

Thanks for the replys guys

So its normal then?

I think it might be, its not using a load and it still drives as normal.

My tyres are all correctly inflasted, well actually ive just noticed a puncture in the front N/S (down to 18PSI!) So ill get that fixed. Although i only checked them last week and they were fine then.

It had a service about 1K miles ago, and had the air filter changed too.

Although ive noticed a slight sticky brake on the front so ill look into that. It wont be helping my MPg will it, but it is only very slight, and only when the brakes are warm.

I got 51MPG last time, so its a little better than last time. I think ill just put it down to the cold weather, and doing a fair few short runs where it doesnt get wamred up properly.

On a long run i got 62MPG, where on the same run a few months ago i got 74MPG. All motorway work at 70ish for about 380 miles.

Last saturday i did 400 miles, nearly all motorway although a it of stuck in traffic too and i only got 57MPG, which i was unhappy with.

So im not sure if its just the weather or what.

Someone on another forum did mention about their MAF failing on their TDi and it using more fuel but still got the same performance.

Chris

 

[brad1]

i cant believe your unhappy with 57mpg, that is quite good

 

[ChrisGTL]

That 18PSI tyre must of been dragging like buggery.

Still worth checking your air filter just to be on the safe side! Don't trust garages TOO much to actualy do the work you pay for.

Dealers are the worse offenders for trying to skank customers now - anything to save a couple quid here and there.

Pug garage has just told a bird who works here that her clutch is knackered, and she may need a new gearbox too.

So we got in and put handbrake on and lifted clutch in 1st gear - back end of car sat right down instantly, no clutch slip......nowt bugger all wrong with it! (apart from she is a she and they proper tried it on with her)

 

[cardaft]

Yep i know, 57MPG is still very good.... but not for my car really, ok i sound like a bit of an idiot saying im unhappy with 57, but i usually always get 65-70MPG on the same run.

The tyre went down fast since when i went to go out last night it was totally flat, so i got it fixed today, needed a new tyre unfortuntely and i dont like replacing only one. So it wont have been harming the MPG, only yesterdyas anyway.

Yep your right, garages arnt always to be trusted, but i changed the air filter myself so its got a nice fresh one in there.

Ill keep an eye on the MPg, see if it gets any worse.

Its probably just the weather though isnt it, a slightl increase is expected, but i just thought it was a bit more than slight.

So then, who has tips on how i can improvie my MPG, think i need to be a more economical driver maybe.

 

[sssstew]

improving mpg is all about thinking ahead, anticipating slow downs or problems, driving smoothly, not flooring it, having a well maintained car and driving within the peak torque range of the engine ie not labouring or over revving.

 

[rv2583]

im lucky if i get 40 mpg from mine

 

[al_b22]

My fuel consuption seems to be improving now ive altered my driving style a little. Basically avoiding labouring the engine or reving too high, as my driving was a bit lazy. Maintaining the revs between 2000 and 3000 rpm at all times, never too low and never too high, I got over 50mpg this time with mixed town and motorway driving. I was previously getting 40 - 45 mpg.

I think the key to good economy on the 1.4TDI is not labouring it at low revs. This seems to waste more fuel than ragging it. After all, its a heavy car, and below 2000 rpm its basically a 1.4 N/A engine as there is little boost from the turbo, and it struggles to move the car - you can even see the unburnt fuel pouring out behind as black smoke! Keeping the revs up allows the turbo to burn the fuel more efficiently, and there give you more mpg (with less smoke! )

 

[EdButler]

TDi's optimal revs for thermal efficiency are usually 1700 (+/- 100) so you should really place your driving around that. 1/3 Below and 2/3 above for accelleration as the efficiency graphs thats i've seen resemble an obtuse quadratic.

Either way, you know when a TDI is overfuelling due to black smoke, so make sure all the airways are clean (inlet maybe coked up or air filter). The cold weather is also a major factor, mine used to drop 5-8mpg easily. Other advice is also sound on here

 

[cardaft]

Thanks for the replies everyone really helpful.

I do tend to keep low revs usually round town and change gear a bit early maybe. So that could be where im going wrong. Although out of town i usually drive it more in the revs so it does do better.

I have found that if driving it quickly in high revs and giving it a bit of welly it doesnt use much more fuel as driven normally.

So i think i need to change my driving a bit then, well just to see if i can get better MPG. Its averaging about 52-55 MPg now with is good for the driving i do.

Although for some reason about a month ago it had an off month and used a load of fuel, but now its back to normal again! Very odd.

 

[deezal]

The cold weather affects mine .The engine takes a long time to warm up, and I do quite short joiurneys mostly. MPG is down about 8-10mpg at the moment compared with the summer when I get around 58.

 

[cardaft]

Ok, my car is at it again, MPG has dropped down again.

Ive found that when its doing rubbish on fuel it isnt as nippy as normal!

Last month i got 61MPg with my usual driving and normal conditions. Under the same conditions and driving now im getting 50MPG. Still not bad i know, but its 11MPG less than i was getting last month

Whats going on? Could something be at fault with my car (MAF, EGR??) that has a intermitant fault maybe? Would this show up on Vag Com?

Its agetting a little annoying now, MPG is all over the place and haveing to fill up more often.

Even on a long run on the motorway the fuel gauge drops a load more than normal

Any advice would be much apreciated

 

[cardaft]

Am i being to picky?

Its just odd how it varies so much!

 

[al_b22]

Probably ties in with the weather being a bit colder again!

Although my 1.4TDI consistantly does 50mpg,and is still doing it currently

 

[cardaft]

Yes your probably right, its the weather. Although seems a little odd to vary this much.

Today ive cleaned the MAF sensor and also put a bottle of diesel treatment in the tank so ill see how it performs on its next tank full.

 

[sssstew]

it will perform better in the colder temps, due to the air being denser.

 

[Muttley]

A couple of things to think about:

Does the poor MPG correlate with where you buy your diesel from? Unless you always buy from the same place, keep a log of where you buy your fuel and see if it matches up. Supermarket diesel in particular often gives less mpg.

Also, in colder months the fuel will be winterised, which means less energy content per gallon. This will vary from source to source, so again it's worth keeping a note of where you buy from.