What is the cause for my Low MPG?

[Masterkm]

I have had my 1.9TDi for over a year now and after a long run back from GTI Festival yesterday, it only returned 175miles from 17+ Litres which calculated to around 45.8mpg.

Now its had a new turbo fitted and runs perfectly fine without any issues but I dont know why its so low. Im sure faster cars are returning better MPG than that.

I know this MPG issue has been covered so many times but would like to figure out what it is, a list below shows the details:

1. Im running 18's instead of he 16's it came with and 36PSI all round
2. Its even remapped whcih should have increased the MPG more, but in fact has decreased it
3. Yesterday car was in cruise at 70mph with the odd overtake
4. Got a performance panel filter, dont know what diff that would make tbh
5. I used REDEX fuel additive in it on that journey, which was meant to improve it but nope.
6. Could it be due to not havin a 6th gear? as staying at 70mph is about 2500-2750rpm?

So is something wrong and what could I investigate to sort it out?

Thanks

 

[LeonCR]

how fast are you driving ?

 

[Masterkm]

Stick to speed limits and change between 1750-2000rpm

 

[LeonCR]

try dropping the speed to 60 on the motorway and see what difference it make

 

[Masterkm]

Will try that when I go to wembley in a few weeks, I know if i do 50mph in the speed restrictions on the mway for a good few miles the mfd shows about 51.3mpg

 

[TarekElsakka]

If you're going between 1750 and 2000 RPMs then you should be getting better MPGs. Sorry, I do not know the reason why you aren't.

 

[steroidchris]

When was the last time you had a full service?

 

[Masterkm]

Serviced yearly and last full service was in April 2012 about 1000-2000 miles ago. Oil and filter was changed again with new turbo end of August. Will be changing oil and filter again on saturday as was advised to after the turbo has settled in

 

[TarekElsakka]

Perhaps you'll notice an improvement in MPG when these things are done. Let's hope so!

 

[Masterkm]

Perhaps you'll notice an improvement in MPG when these things are done. Let's hope so!

I really hope so, because i look at the FR's and other cars with 2.0litres and they can easily achieve what I have even by driving fast

 

[steroidchris]

Serviced yearly and last full service was in April 2012 about 1000-2000 miles ago. Oil and filter was changed again with new turbo end of August. Will be changing oil and filter again on saturday as was advised to after the turbo has settled in

So, by changing the oil and filter on Saturday, that'll be 3 times in 6 months. I can't see it making any difference.
Could it be over fuelling?

 

[peter3hg]

Has the car been re calibrated for the new wheels? They probably have a slightly larger overall diameter including tyres.
My old shape Toldeo with that engine would return over 60 mpg on a long run averaging around 80 mph on the motorway. That was also remapped to ~142bhp and a ludicrous amount of torque.

 

[Masterkm]

So, by changing the oil and filter on Saturday, that'll be 3 times in 6 months. I can't see it making any difference.
Could it be over fuelling?

Hmmm how would I be able to investigate this? Is it a case of taking it back to P-Torque?

Has the car been re calibrated for the new wheels? They probably have a slightly larger overall diameter including tyres.
My old shape Toldeo with that engine would return over 60 mpg on a long run averaging around 80 mph on the motorway. That was also remapped to ~142bhp and a ludicrous amount of torque.

Re Calibrated? I just smacked the wheels on and that was it, got them from another member. Thats what im thinking bigger cars get better mpg and im wondering what is the issue?

 

[GrahamFR]

if the new wheels arent the exact same size as your old ones ie. tyre width plus alloy inch, then they will throw out your readings in both speed and mpg. (but they should be as the bigger the rim the thinner the tyre width)

However, did p-torque map your car before or after you changed your turbo?

 

[Masterkm]

The car was mapped before the turbo in April. Turbo changed in August. The readings are pretty much the same as my calculations +/- 3mpg

 

[GrahamFR]

The car was mapped before the turbo in April. Turbo changed in August. The readings are pretty much the same as my calculations +/- 3mpg

is it the same turbo? if not this might need your map redoing or even if it is the same turbo its possible they might not be exactly the same if you know what i mean.

Give p-torque a call and ask them what they think

 

[Adman77]

Isn't 36psi a bit high? Esepcially on the rear?

 

[shnazzle]

We get about 42 to 45mpg with my wife driving the CR170... so... I don't see the problem. 45.8MPG seems pretty good to me.

Mind I'm still very fresh off the 25-28mpg boat after my FR TFSi so anything > 35 is a miracle to me

 

[GrahamFR]

36 is a little high but shouldnt negatively effect mpg, should make it better tbh.

and its not bad mpg overall but it is bad for a 1.9tdi and if you stuck at 70 all the way a CR170 should get 50 over a decent distance

 

[Masterkm]

Its a new turbo as the old one was totalled, was thinking about giving P-Torque a call and see what he can do for me. But busy atm with work

I might reduce tyre pressure a bit to see what that does, but im sure it wouldnt make much off a difference