Fuel Consumption

[bobak]

Hi,
I just solved a bunch of previous issues with my 56 plate Leon Reference Sport (PD 140) TDI by replacing the turbo with a brand new one, new fuel filter and oil change.

Anyway, the car's running very nice, as i'd expect it to, so quite happy there.

My remaining issue is the fuel consumption.

Just before i bought the car, I borrowed my friends Golf GT Sport TDI (140Bhp) 2008, which has almost the same engine. It might be a CR, i'm not sure. Anyway, sat at 70mph i'd get 50-51mpg and at 80mph i'd get about 48mpg.

I bought the Leon and at the same speeds (same journey and fuel etc too) i'd get about 47mpg at 80mph and about 49mpg at 70mph.... and about 50mpg at 50mph in the yellow camera zones.


So... before my turbo needed replacing, I was getting about 36mpg generally. I was told it's the turbo and it would be fixed once it was changed out. I changed it out - as I mentioned before - making sure the Oil Feed/Return pipes, Oil Filter, Fuel Filter and Oil were all changed for new ones and i'm getting about 39-40mpg on the motorways now on average.

This is obviously quite poor. Any suggestions? My friend said i need to reset the ECU after the turbo change by disconnecting the battery. I thought perhaps the MAF?

 

[EndlessNameless]

It's probably far too obvious, but check things like tyre pressures, you can lose a lot of energy unnecessarily deforming the rubber.

 

[bobak]

You reckon a loss of 10mpg from tyre pressure? I'll check but they look ok.

 

[AndrewJB]

Them MPG's are very low for a PD140

My PD170 was achieving them MPG'S , My Mates mapped MP140 gets high 50's

 

[bobak]

Yup. Agreed, hence I want to try and do something about it. Sometimes I get about 44mpg poodling behind some learner driver but otherwise it's been dropping low. Hence I'm wondering if my maf died a bit or something, just after the forums thoughts

 

[greyfloppyhat]

It will take a couple of runs for the ECU to readjust it's self to having better fuelling, more air etc. This is what I've noticed after servicing cars that are miles past they're service interval (not my own I'd like to point out) they still run a bit crap for a while but it soon adjusts and everything is well again

If your still having issues a couple of journeys on have a read through this
http://www.myturbodiesel.com/1000q/multi/low-power-fix-TDI.htm

 

[bobak]

Ah ok.
For the record though, it was serviced 7000miles ago so not overdue but I guess it has effectively just had major surgery!

 

[greyfloppyhat]

Ah ok.
For the record though, it was serviced 7000miles ago so not overdue but I guess it has effectively just had major surgery!

That's what I mean, the ECU has adopted to running on a broken turbo, it will take a bit to re adjust back to 'ideal' conditions

 

[bobak]

Ahhhh I get you. Is it true that if I leave the battery disconnected for 30mins or so it will reset those learned settings and return to default?

 

[greyfloppyhat]

Possibly but it will still have to learn to adapt to the engine as it won't be 'default', and neither will your driving style. Your best just to do a few trips and see how it goes. If after a week your still not happy then try disconnecting to reset everything(although I'm 100% works) or go through the list I linked.

It is possible there may be a small leak somewhere as the piping for the turbo, especially the intercooler never seals as well when it's removed and placed back on. Unless they renewed the o rings

 

[bobak]

The clip was recently renewed to the intercooler. Not the o rings. Ill stick it out a week and see, already done about 350 miles since fitted on friday

 

[bobak]

SOLVED:
Turns out its my right foot. Drove to work in a hurry this morning...got 40mpg. Drove home smoothly and steadily, not going above 80 and 51.4mpg average.

 

[Deleted member 74601]

lol.

I can't believe how many people say don't use cruise control. It's so much better overall than I am.

 

[rowley2k9]

Mines pretty crap only live 3 miles from work so most of the I see just about 30s if I do take it on a long drive I get about 45s

 

[Nath.]

lol.

I can't believe how many people say don't use cruise control. It's so much better overall than I am.

Agree, I hear a lot of people saying that they reckon they can do better MPG than CC. Personally, on a long run of say 50 miles or more there is no way I can do better. It would cost be another £60 in fines too.

 

[Deleted member 74601]

Agree, I hear a lot of people saying that they reckon they can do better MPG than CC. Personally, on a long run of say 50 miles or more there is no way I can do better. It would cost be another £60 in fines too.

Same here. I've no points since getting cruise control

 

[Jarre]

Same here. I've no points since getting cruise control

That's the only thing i miss from my clio, but to be honest i didn't use it that often. It can be retro fitted though, i believe.

 

[Deleted member 74601]

That's the only thing i miss from my clio, but to be honest i didn't use it that often. It can be retro fitted though, i believe.

Yeah, probably won't be hard. Most models tend to have the required modules, you just need to add the stalk and some sensor/controller.

I do mostly motorway miles so it gets a bloody lot of use, but when I found out it was more economical than me, I started using it in 30 and 40 zones.

 

[EndlessNameless]

Agree, I hear a lot of people saying that they reckon they can do better MPG than CC. Personally, on a long run of say 50 miles or more there is no way I can do better. It would cost be another £60 in fines too.

Should be possible in theory.

Most of us don't have that kind of concentration though.

 

[bobak]

I don't have cruise control on mine. One thing I regret not getting, but actually in a diesel I find it a lot easier to just maintain a steady speed.
As for the 3 miles in the diesel...yes you won't get good mpg...the cars not even earned up and lets hope you don't have a DPF...otherwise start saving for that bill.