xantia HDI fuel consumption

[isisalar]

Happy Easter everyone. My HDI seems to doing about mid 30's fuel consumption and I'm sure it should be better. The use is not the most favourable, a bit of weight on board, a roof rack on, a mix of driving but including a lot of short journeys and lately a lot of ticking over just to keep warm.
Car starts fine, pretty much as the TD did when warm, but never on the first crank like the TD did when cold, I don't know whether this is normal for an HDI. No smoke, a very slight diesel smell from the exhaust when started from extreme cold but nothing like as much as the TD with 3 working glowplugs. The engine hasn't missed a beat since i got the car and it drives beautifully. There is a slight 'stutter' after running for a couple of minutes from cold whilst driving on a small 'throttle opening' but for no more than a second or so, its then gone until the next cold start. I've not seen the temp over 75 yet and would have changed the thermostat but have been told more than once that this is normal.
Checked the air filter-fine.
Cleaned the maf- improved engine driveability enormously.
I put in £35 diesel last week with a dose of Slick 50 fuel system treatment with an estimated 10 litres in the tank. As expected the engine is now performing even better, the stutter remains but I think it's gradually improving, however I've just clocked 110 miles and I'd estimate I'm about halfway through the diesel, obviously need to run the cleaner through the system fully.
I read in a post today, about a petrolC4, that disconnecting the battery for 30 mins to clear the ecu of nasty thoughts might improve things, would this apply to an HDI?
Could anyone suggest anything else to try please?
Would a Lexia session help?
The car is in extremely dire need of a hydraflush and filter clean and will be done as soon as it's warm enough, would this be a factor?
Kind regards
Paul

[Northern_Mike]

The Berlingo was doing this, and returning poor economy recently, about 35mpg. Shocking. I filled it with diesel, and really thrashed it for an entire tank, taking it up near the redline, driving it at 70-75mph in 3rd down the motorway, and generally revving it hard.

It's fine now, last 15 litres worked out at 44mpg, back to normal.

[isisalar]

That sounds like a lot of fun but a trifle impractical and antisocial on the mean streets of North London Mike. I do have a scenic route I can take on a regular journey I'll be doing tomorrow, going to Garston and will certainly give it a go, but one time on said route, but for a mimser, I would have been caught in a radar trap so I am very wary on that road on Saturday afternoons. M1 home though!
Cheers
Paul

[citroenxm]

Ive a HDi 110 Exclusive. with 240k on it. She is still returning around 53mpg (Shes a hatch though, not an estate).

I do though have my boot FULL with all my tools all the time, so is quite heavy. So I find 52mpg actually VERY good indeed. Also a tuning box is fitted too.

35 sounds awfull! Have you removed the engine cover and had a look for any fuel leaks from for example the leak off pipes, or even weeps from the high pressure pipes. You will know this from having damp injectors.

A HDI, if all hi speed heating heater plugs are working, should start first turn of the key NO ISSUES... If its not, then theres a fuel issue some where.

[Citroenmad]

My Hdi Xantia does about 52-54mpg on average, which is excellet in my book.

Sounds like there is something wrong, try giving the maf a clean with some electrical contact cleaner. I did that to mine recently and MPG improved even more.

[Peter.N.]

They should be capable of 60 mpg driven gently under ideal conditions but with short journeys, very cold weather and idling to keep warm that could well be about right. Take it on a longish motorway or quiet 'A' road journey at a steady 60 mph and see what it does.

Peter

[citroenxm]

No, 35 is not good what ever the weather! I dont think it is anyway...

[Rhothgar]

If you nail it on a regular basis from lights, you will only get 35.

A long motorway run should give 60 driven on a steady throttle.

[isisalar]

No room to nail it round here, that might be the problem. I was expecting 50+ so I'm a bit disappointed. What about this ECU thing? If it still thinks its got a dirty MAF and injectors can I clear that by disconnecting the battery so it can learn the new values? Would a lexia show anything up? I'm new to this electric diesel stuff.
If it did 20mpg I'd still love it but I'd love it a lot more if it did 50, cant wait to do the hydraflush.
Cheers
Paul

[Citroenmad]

No, you shouldnt need to be disconnecting the battery, its all to do with sensors. If things are clean and its running well, it will know.

Im sure if I lived in London I would get similar MPG, my town MPG is about 40-45 but thats taking it easy and not sat in too much traffic.

How does it perform? Usually a lack of performance will give a lack of economy.

[myglaren]

Can you get one of the members closest to you with a Lexia to run a diagnostic. May be enlightening to see what that throws up.

[c.morewood]

Nearly 260k and the worst I ever got was 45mpg 80mph down the motorway 5 up with a topbox and full boot. Generally 1 or 2 tankfulls in late Dec to Feb gives about 48 mpg otherwise in the mid to upper 50's.. Haven't quite got 61 yet.. 35 tells me there's definately something wrong.. Are you sure you're calculating it right?

Chris

[electronmirror]

I have the same HDI Exclusive estate and regularly get 45-48mpg when trundling through stop start traffic. It improves to 55-58 ish when on a run at 'healthy' motorway speeds. The only time it has dropped to 40mpg was when the MAF began to fail, cleaning it produced a temporary improvement but it had to be replaced with a genuine Siemens a few months later. That was 3 years ago and the consumption has been pretty consistent since I bought the car 10 years ago.

[isisalar]

That's exactly what I'd like to do(Lexia session). What can/does this show?
There is no lack of performance especially since the MAF clean, the improvement whilst using the system cleaner will, i know, be temporary. Any lexia volunteers available over Easter? Don't mind traveling a bit.
Kind regards
Paul

[Northern_Mike]

That's exactly what I'd like to do(Lexia session). What can/does this show?
There is no lack of performance especially since the MAF clean, the improvement whilst using the system cleaner will, i know, be temporary. Any lexia volunteers available over Easter? Don't mind traveling a bit.
Kind regards
Paul

If you can get it to Staines about 2pm Sunday to my office I'll take my lexia to work. .

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