Having returned to a Grand Voyager after year in a smaller Eurobox MPV, we love the 2.8 auto, but we're only getting 20mpg!

Towing our caravan dropped it to 19, round town is 20, a long run up the motorway is 20...

Our previous 2.5 manual GV was much better giving 35-40mpg for similar journeys.

Is this what we should be getting or should we be seeing better economy?

If so, where should I start?

Many thanks

Steve

 

Everyone's mpg is different, but you should be seeing at least 30mpg. Are you using the computer to tell you the mpg or calculating yourself?

Regards
Richard

 

As Tfb says, you should back up your fuel economy estimation as computed with the brim-brim method yourself. I do this at every fill-up. To date I would say the computed read-out is not bad, working by counting the length of time the injector is open and squirting fuel, vs. the distance covered. (Solenoid injectors have three squirts per power stroke). Dirty injectors could upset this by making the fuel droplets too big for efficient combustion, therefore less power, therefore more pedal to compensate. And a little black smoke on hard acceleration.

There is one other point I'd check.
Jack each rear wheel off the ground, handbrake off, and see if the wheels turn easily. Even a slight brake bind will ruin your fuel consumption figure, and GVs ARE PRONE to back wheel brake bind. The handbrake design and its tortuous cabling, plus as Qinteq says its less than perfect design anyway causes this. The innards of the brake shoe operation get frozen up with rust, dirt, corrosion etc.

With a diesel automatic GV, some fuel can be saved by coasting in neutral as the hypermilers do. Maybe in the area of 5 to 10%. 30mpgUK should be attained in general town driving if there isn't too much traffic congestion.

But remember, fuel consumption is never as good as you'd like it to be!

Leedsman.

 

Chaps - thanks for your input so far.

The calcs are done via Fuelly.com so litres added and miles driven. The computer reckons we're doing 12.4 liters/100km, so about 22.8mpg so about right...

I'll jack it up and look for a binding handbrake.

There no visible smoke on acceleration, but before we bought it didn't cover that many miles in the year beforehand, and it was a reluctant starter for the first couple of weeks, so with dirty injectors in mind, any recommendations for a additive to add to the tank?

Any more thoughts from anyone else?

Thanks

Steve

 

HiYa sjbilton,

Right clog [and a boot full of tools] is always the biggest contributor to a thin wallet. I don't tow and get 33MPG average per annum on the overhead EVIC [Electronic Vehicle Information Center] counter. These gearbox's [41TE] have a learn mode time every time the battery is off. Drive with your clog down while its in learn mode and that's what your gearbox brain decides is your driving style, it then gives you Schumacher speed and consumption figures.

In a 2.8 if you never get out of 30MPH town driving in a week you will be lucky to do 20MPG because you will never get into top [auto box] gear. 30% town and 70% elsewhere should give 30+MPG. You will get the best MPG at this time of the year and a noticeable reduction in MPG in the winter. Cruise control is about a 500RPM saving in top gear. ASDA and other supermarket fuel lack the additives - you get what you pay for. I've read it and you've read it, so my brother and I did a neck to neck test [2 different cars] 2 years ago and it was more than a mile per gallon difference - no science - but a fair test at £85+ per tank.

Do a cheepo test :

- clear your EVIC and MPG from the car memory
- find a 50MPH clearway, 10-15 miles using cruise control what MPG do you get ? 50MPG ?

- clear your EVIC and MPG from the car memory
- find a 70MPH clearway, 10-15 miles using cruise control what MPG do you get ? 30+MPG ?

 

If you're going to clean your injectors with Forte' (the only one mechanics use), don''t just pour it in the tank. Mechanics pour some in the diesel fuel filter, reassemble and go for a drive, giving it some boot now and again.
I suppose you could run the fuel tank very low, then pour the lot in the tank, but it may not work. Then you've £15 gone... (Although I get it for £12 from the guy who does my MOTs).
There is also a possibility of trying BP's special cleaning diesel-ultimate at 40p a gallon extra, and I think there is a Shell equivalent to that. Might be V-power?

Leedsman.