Poor MPG

[albert81]

There's no reason to be worried about anything. ........after all u get 44mpg.

[.....]

Originally Posted by albert81

There's no reason to be worried about anything. ........after all u get 44mpg.

but I was getting more...hummm

[Avulon]

Have you run the on-board diagnostics temperature monitor? maybe it's not getting up to temp. Plenty of info on diesel thermostats and running temperature and relationship with mpg on the forum.

[vindaloo]

I wish my diesel delivered 44mpg.

[.....]

Originally Posted by Avulon

Have you run the on-board diagnostics temperature monitor? maybe it's not getting up to temp. Plenty of info on diesel thermostats and running temperature and relationship with mpg on the forum.

See first post!

[Avulon]

Originally Posted by .....

See first post!

I did. Of course I did make a natural assumption that the car wasn't bowling down the road at 70mph when that reading was taken, I could be wrong...

87 on the T4 with the car standing still is quite different to rolling down the motorway with a 70mph breeze through the radiator. Unless the fan is running the radiator will do very little to cool a stationary vehicle unless it's angled to let some convection to take place. My question was aimed at evaluating the performance of the thermostat. A premature opening thermostat or one stuck open will have little to no cooling effect unless the car is moving.

[Doc Evil]

There could be many contributory factors as to why your not getting same MPG will list a few take your pick
wear in the sensors (as they get older their performance dan deteriorate )
Different fuel (even from same garage it can be different from time to time depends on where its refined)
Weather conditions (head winds placing extra drag on car or very hot air can have detrimental affect on combustion efficiency)
Driving conditions (idiots pulling out in front of you or having to accelerate more often even gently will use more fuel than coasting or constant speed)
Brakes binding slightly (a sticky piston can play havoc with your MPG)
Aircon issues if used
Extra electrical load (it all has a detrimental affect)
Dirty car (if airliners quote it as an issue why not us) lol
I'm sure others could add to this list of things that may have had a cumulative affect



Doc

:cool:

[polinsteve]

I blame **** modern derv. We had 3 diesel 75s in the family and all achieved close on 50mpg on a run. Since the advent of "cleaner" diesel I get about the same as you. The only way I can achieve 47-48 mpg is to keep the speed down to 60-65 mph and that is not usually an option I care to choose.

[clf]

Originally Posted by .....

Ok I'm looking for some ideas as to why my mpg has gone down.

Motorway driving at 70/75 mph the car will only return just over 44 to the gallon.
It used to give more than that.

The car is a diesel manual with the 160 map on it done by Brian.
The engine has had a tetra clean treatment. The oil has just been changed along with the crankcase breather filter.
It's also had new vitron O rings fitted I got from Jules.
It has an ERG bypass fitted and an inline thermostat fitted ( engine temp measured at 87 degrees on the T4 session)
The car has only done 94 k

When I noticed this a few weeks ago I took the car to Rich and he put it on his T4 which confirmed the Maf sensor was fine but said two of the injectors were iffy. I have had both of these injectors refurbished and although the car runs smoother it has made no difference to the mpg.

I've just come up from London and over a 300 mile round trip (nearly all motorway) the car has still only returned 44.1 mpg.

Has anyone got any ideas whats causing the poor mpg?

How much more than 44 mpg are we talking about? It would be realistic to see a drop of 3-5mpg with air con on. Similar with tyres slightly low.