fuel consumption

paco · Unread post by **paco** » 18 Dec 2006, 12:14

hi

i drive a 1995 1.9 td it is currently returning around 30 mpg, is this reasonable, it is not driven hard and most of my mileage is a38 duel carriageway, is there a solution, am i being unreasonable

paco

Unread post by **Peter.N.** » 18 Dec 2006, 12:35

It doesn't sound very reasonable to me! Driven gently on a long journey my 2.1td XM estate will top 50 mpg! I take it that its not an auto, if so that could well be about right. A manual ought to average around 40 mpg unless driven very hard or constantly in traffic.

steelcityuk · Unread post by **steelcityuk** » 18 Dec 2006, 12:36

Doesn't sound very good to me. Have you checked for dragging brakes and such like?

Steve.

paco · Unread post by **paco** » 18 Dec 2006, 13:44

its not an auto and the brakes do not drag, just passed mot on friday, so where should i look first

Unread post by **Peter.N.** » 18 Dec 2006, 14:31

Does it smoke? Have you done a brim to brim tank test to ensure that your estimate is correct? Any sign of fuel leaks?

Unread post by **CitroJim** » 18 Dec 2006, 15:01

Peter.N. wrote:Does it smoke? Have you done a brim to brim tank test to ensure that your estimate is correct? Any sign of fuel leaks?

Good points. Also, a good, full service is not a bad idea, especially oil and filters.

If it smokes, what colour and under what circumstances? Smoke is one of the best diesel diagnostic tools there is!

Do you have any general running problems at all? Any starting problems?Is it feeling underpowered? Do you have a definite surge of power between 2000 and 3500RPM as the turbo spins up and gives boost.

I'd firstly suspect a fuel leak followed by turbo trunking loose/leaking and thereby reducing boost, leaky boost sense pipe to injection pump, cracked intercooler, leaky injectors, injection pump timing and blocked exhaust.

I'm inclined, at this stage, to think your high consumption is caused by one of the above causing the engine to develop less than normal power and you compensating by giving it more throttle and thus consuming more fuel.

jeremy · Unread post by **jeremy** » 18 Dec 2006, 16:54

Also worth getting underneath and making sure for example that the fuel tank isn't wet with diesel (or anywhere else for that matter.)

Another silly possibility if all seems well otherwise and you have the Roto-diesel pump is the leakoff pipes - I've had problems there a couple of times on the ZX and all you really notice is a faint smell of diesel - and the engine has dried off unless you look at it while its running. There is probably a small end cap on the injector nearest the thermostat (opposite cambelt) and I had one of those split.

BrianM · Unread post by **BrianM** » 18 Dec 2006, 17:37

Check the fuel pipes as they come up towards the priming bulb from under the car - but you should smell diesel or see wetness around the drivers side wishbone. 30mpg sounds bad - on the 2 Xantias I've had low to mid 40s is the norm

Brian

AndersDK · Unread post by **AndersDK** » 18 Dec 2006, 18:40

Would a '95 (turbo) diesel be MOT tested for any bad emissions in UK ?
If so you should have a printout of the test figures as a leader for fault finding.

If NOT - I'd suspect the diesel distributor pump fuel volume setting. A popular item to fiddle with to get more power on diesels. May not even smoke noticeable from exhaust.

paco · Unread post by **paco** » 18 Dec 2006, 21:30

no smoke unless i really boot it, this creates a large cloud of black smoke

Unread post by **CitroJim** » 18 Dec 2006, 21:43

paco wrote:no smoke unless i really boot it, this creates a large cloud of black smoke

That is quite normal and is produced in response to the pump delibrately overfuelling at full boost under heavy load. However it should not be large nor constant, more of a haze most visible in the lights of a following vehicle in the dark although it is often seen as a big cloud if you really boot it after pottering slowly through a town or when rapidly overtaking a very slow vehicle you have been following for some time. I have created several smokescreens like this in the past to quite spectacular effect. It should very soon clear though and even sustained running at full boost/high load should produce a clear exhaust.

30 mpg is still way wrong though. I only get that sort of consumption when I'm towing the caravan!

whitecrook2 · Unread post by **whitecrook2** » 18 Dec 2006, 23:36

For reference, I get around 32mpg driving 10 miles over 30-40 mins in town with maybe 3 miles of that 50mph dual carraige way. ('96 1.9td) Much better on a longer run, though. This is based on all of last years mile/fuel readings. It's fair to say I have a heavy right foot though.

Unread post by **Peter.N.** » 19 Dec 2006, 09:46

Could be a defective thermostat. Does the water temperature rise fairly quickly and then stay reasonably stable, does your heater give you a good blast of hot air? If the engine is running cold it will affect your fuel consumption.

paco · Unread post by **paco** » 19 Dec 2006, 21:48

thermostate replaced, brim to brim check shows 42mpg.

thanx to all who contributed.

f00lzz · Unread post by **f00lzz** » 21 Dec 2006, 17:38

Brim to brim method I average 41mpg (last check) and I also travel the A38 between Sutton Coldfield and Toyota... perhaps you are that maniac in the Xantia that flys past me everyday doing about 90mph !!!!