Heavy drinking diesel

[chunkolini]

We are in France and our diesel doblo is drinking way to much, like 38mpg.
Last year on this trip we did around 46 to 48. Mostly on autoroutes.
Ages ago on my old doblo my mot man put some 'additive' in which sorted it.
I know nothing about this stuff so some simple advice and ideally a europe available product name would be appreciated.
Car us driving fine otherwise

 

[lexi]

Apart from the usual suspects like blocked cat or dpf, I would check for a sticky caliper or handbrake and rule that out. Get it plugged in for any codes.

 

[voipio]

Have you hit any potholes, or caught any of the wheels on a kerb? Check the tracking, front and rear, and look for tyre scrub/wear at tyre edges. Are the tyre pressures OK? Is there any smoke out the back when accelerating?

 

[jenki]

Air filter blocked? Otherwise brakes binding possibly handbrake cable sticking.

 

[Bullet2012]

Fold up your kites and put them away, trying to tow them will create excess drag and dramatically increase fuel consumption.

 

[Guineafowl]

The additive might have been injector cleaner, Redex or similar. I’ve never found it works, but some swear by it.

If there’s any black smoke you might be looking at a boost leak - check for split hoses.

Dodgy MAF sensor - try unplugging and see if there’s a difference.

For brakes, very carefully touch the discs/drums after a short journey, to see if any are hotter than the others.

 

[8ob]

Always worth checking the bathroom scales, just saying

Bob

 

[Tangledfeet]

Hotter this year maybe - air conditioning being used more?

 

[voipio]

Have there been much into the wind driving?

 

[Tangledfeet]

Have there been much into the wind driving?

Or wind inside the car and other passengers have insisted on windows being open..?

 

[ostosix]

I think two stroke gas the same effect of vleaning system. . Make sure its go no leaks, leak of pipework. On long runs you’ve no way of spotting a leak like day to day on driveway.

I found fuel leaking from leak off line on my disco3, only realised cos i smelt diesel, looked underneath and then was able to track it back up to a fuel pump return connection

 

[Morrisman]

Always worth checking the bathroom scales, just saying

Bob

I’ve been puzzled why my bike has started giving 50+ mpg over the last six months, whereas for several years it was a rock steady 45mpg everywhere, 10 miles to the litre. I had an idea it was changing the gear oil and final drive oil.

You’ve just made me realise, I’ve lost 3 stone over the last year.

 

[chunkolini]

Would two bikes mounted on the back cause excess drag?
We did not have them last year

 

[Trevorleach]

Would two bikes mounted on the back cause excess drag?
We did not have them last year

Massive amounts of drag

 

[julianthegypsy]

Would two bikes mounted on the back cause excess drag?
We did not have them last year

Yes it would!

 

[voipio]

Bikes, yes, though look at the other possibilities, too.

 

[julianthegypsy]

Years ago someone calculated that putting a bike on the roof would use so much extra fuel from London to Edinburgh that it would pay for a rail ticket. Roof is worse than rear but is still a huge drag.

 

[sako243]

Years ago someone calculated that putting a bike on the roof would use so much extra fuel from London to Edinburgh that it would pay for a rail ticket. Roof is worse than rear but is still a huge drag.

Not with current ticket prices

 

[julianthegypsy]

Not with current ticket prices

Yes, that had occurred to me! I believe when it was originally done it was a first class ticket too. For that price you could probably fly, with your bike and pay for a week's parking at the airport at today's prices!

 

[Farside]

Would two bikes mounted on the back cause excess drag?
We did not have them last year

Definitely. It might seem the back end is just blunt originally, but the bikes will contribute a load of messy chaotic drag.