407 sw fuel issues?

[Vaux]

Hi all. New on here so hello everyone

Im having a few intresting issues with my 407sw 1.6hdi manual 5speed (2008-58 plate)
Its mpg has been poor most of its life but its getting worse im now finding it hard to get above 34.7mpg, im now lucky if getting 440miles to a tank (last fill was 62.5lts and got 452miles but dont drive it right down like this normally)
What really kicks is i also have a citroen grand c4 with same engine and im getting 52mpg out of it and i dont drive no diffirent, so the fact the c4 is bigger/heavyer and poor aero wise tells me somthing is wrong with the pug?
As this is my working car i need better mpg as its costing too much for it,
I swapped the 406 for this and that was a 2.lt and it got 40ish mpg,
Ideas?
Thanks

[jmkent]

Quite a few things can affect mpg... when was it last serviced, oil & filters? Do you carry weight around in the boot? Roof racks? Tyre pressures?

If none of the above, then you may need someone with Planet to give it a scan and see if there are any faults present

[sterion75]

I am getting between 39-42 from my 1.6 hdi if that helps, mixed driving and a light foot. As jmkent says, would pay to get it scanned with pp2000, it could be a fault such as fuel pump etc, you wont know without a global test for faults

[jmkent]

I'd have expected you to get more than 39-42 from a 1.6 - I'm getting that with my 2.0, and that includes a lot of short journeys with a cold engine (only 3.5miles for me to work, of which the first 2 are up hill barely getting 16-18mpg )

[Vaux]

Yes she has roof rack on with ladders and steps on,
Yes she carries alot of weight in the back, (+200kg)
Tyres pressures are on the high side, front at 2.8 and rear at 3.2bar,
Tyres are in good nick and only get through fronts every 24k and rears at 34k so not hard driving,

No fault lights on, when new had major faults with depollution faults and engine faults which turned out to be te ecu failing, (replaced at 23k)

Shes going on ramps in morning to see if theres anythink binding on brakes

£90 @1.42,9 = 415 miles again!

Also tryed main garage fuels over cheeper super market type made no diffirence apart from the 1-2p per lt more,

[jmkent]

That is definitely much higher pressures than recommended, which I believe is 2.6bar front and rear 2.6bar, and 2.8bar rear when loaded.

I think you've found the reason for the poor fuel.... rook rack with ladders and 200kg of weight in the boot is going to make one hell of a difference, especially as its the 1.6 without a lot of grunt to overcome all this.

[Vaux]

There load rated tyres so will be different,

I would agree with that conclusion but why does a 307 same set up same load manage 46+ mpg, also +8months ago the 407 was low 40's?
I do know what you mean though,
Also the c4 still beats it when roof box on and van on the back which is rated at 78% load weight and still gets 42+?

Think a trip to usless puegeot is in order! Last time they caused more problems then they fixed typical stealers

[jmkent]

I can see why the 307 would get more than the 407, probably just due to size/weight between the two, but as for why the 407 has dropped in recent months, who knows? Best bet probably is as you say to get it checked over, and the brake check probably worthwhile

[Vaux]

I know makes no sense in my eyes, nor the person whom pays for my fuel card, as been questioned why there is such a difference and im at the garage more and do less miles?

Theres only 160kg diffirence between a 307 and 407 any way,

Just looking for ideas?

[sterion75]

I am disappointed jmkent, especially as I was told 67mpg was possible before i bought it. Got me fair excited. I have changed all the filters, its showing regular regens but the engine cooling fan shows not working. This puzzled me no fan but regens mm. Tried direct wiring and actuator test, nowt. I dont welly it, and keep inside the speed limits even with my new speed limiter toy, 49 would be better, but no.