High fuel consumption on 1.4TDi

[cardaft]

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

Its MPG is always worse in the cold, but it does seem to perform at its best when cold, ive got to say though temp doesnt make much difference to its power, just MPG.

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.

Yeah thats something to bear in mind, thanks.

Although generally i always get my diesel from the same Shell garage. I try not to use supermarket fuel, ive used it once this year and the MPG was quite low.

Well ill see how i get on over the next week/tank full with the MAF cleaned and a fuel system cleaner in now.

Thanks.

 

[cardaft]

UPDATE:

I still need advice with this!

Ive had this problem since i started this post late last year!

My MPG is getting worse, sometimes its hard to get over 45MPG, in a little 1.4TDI!

It drives and goes ok, it doesnt smoke more than normal and there are no fault codes present

I have bought a scanguage now so i can measure my MPG. Sometimes it does great and i can get 65-70MPG on a good run with MPG in mind.

Although sometimes its hard to get it over 50MPG, driving economically.

I have checked the scanguage with my calculated MPG and adjusted the gauage slightly to be more accurate.

One thing i have found since getting the scangauge is - if its doing badly it improves if i floor the car through the gears then continue to cruies at the speed i was at before the MPG increases when it settles. Although it often goes back to bad mpg a few minutes later.

So its as if something isnt switching or something. I know nothing about the electric side of cars!

Ive had it to the garage i use a few times and all he basically does is check for codes and says its fine. I know it isnt though, my average atm is about 48MPG, which is about 10 lower than i ever used to get.

Im seriously considering selling it, im getting a little depressed with it.

Any ideas anyone?

 

[SenorJose]

I think you should try to clean the intake manifould - perhaps with Bell-Add spary.
I had the problem with my old Skoda Octavia - it is particles from the exaust that are getting in via the EGR and building up in the intake - in my case only about half the area in the intake just after the EGR was free - and with a build-up like that MPG gets poor. Prehaps EGR cannot close properly .... ?

- Senor Jose

 

[Mr Biscuit]

I wonder if its intermittently cold fueling.
Have you checked / changed the enging temp sensor.?

I have an intermittent fault with the dash temp sensor (other half of same sensor), temp drops to zero, very rarely happens, & doesn't seem to effect MPG, which when not enthusiastic is 65.

Injectors are probably OK as your scangauge is accurately telling you what your MPG is. Double checked by your fill up calculations. This also rules out a fuel leak. (Scanguage calculates MPG from injector fuel volume settings as set by ECU fuel map)

Next would be the MAF (which you have cleaned) but usually when these degrade they produce a drop off in performance, which you say is OK.

You're seeing a 23% drop (65 down to 50), I'm sure this is a component fault rather than say tyres ,fuel, airfilter & the like, which individually might influence 5%.

I dont understand however why a hard acceleration temporarily improves your fuel consumption.

Might be worth putting your scanguage in a friends Arosa/Lupo Tdi and getting some benchmarks for you to compare against.

Also would be interesting to see what MPG is lke when the engine is cold ( not that its that cold at the moment)