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My HDi 110 doesn't seem to be as superbly economical as some of the others around. Have heard of lots of people getting 50mpg+ & the best mine has ever done is about 45 on a very long motorway run.

Whilst cleaning the engine cover I noticed that under the injector rail I have little puddles of black liquid - there's like a little shelf under the rail that it sits in - & it seems too thin to be oil. Is there any chance that I've got leaky injectors or a leaky rail or anything like that which could also be affecting my fuel consumption? Have had it running with the cover off & can't see anything p**sing out anywhere, but it could just be coming out when I'm putting my foot down.

Anybody got any ideas & would any of them be a fairly straightforward DIY fix?

Lots of HDi's get this black stuff and most say it's oil from the rocker gasket and also the breather tube off the head.

A diesel leak will show as a clean area mostly as the fuel kinda washes stuff away.

45mpg aint too bad but you should be able to get 50 if you try to. There's only the obvious stuff like tyre pressures, air filter, driving style etc to suggest at first and then maybe a live code read to see what the HP pump is producing.

That's a relief then. Had an HDi 90 Xantia a couple of years ago with the same thing, but from what you say it definitely isn't diesel as it is very black. If it is an oil leak it is just a dribble too as I think I've had to top it up once since it was serviced in April - hardly uses any at all. Am seriously contemplating getting that KWP stuff off Ebay & doing a DIY remap, but didn't want to do anything if there were any possible probs or leaks in injectors.

Maybe I'll give that a go & see if better driveability improves things. How would I get that live code read to see what the pump is producing? Is that just the same as getting fault codes cleared?

A good code reader will tell you the live rail pressure at tickover and higher rpm's. Apparently a steady 298bar at idle is a good indicator rising to 1000bar I think but a rock-steady idle reading seems to be the one to watch.

Re-mapping very often produces higher mpgs (once you stop playing that it)

I only get 41.5mpg avg, but then again mine's tweeked a little bit

Only black stuff i've got is soot from a leaky egr - might have to make it disappear - the egr that is