Xantia Running temperature / Fuel consumption

hamster · Post by **hamster** » 31 Jan 2009, 12:55

Recently my fuel consumption has started to increase. I used to be able to do 420 - 450 miles before the fuel light came on and its dropped suddenly to about 350, yesterday it came on after 335 although i know i can do best part of 100 miles with the light on.

I also noticed that my coolant temperature isn't getting very high, about 70 -75 degress even after motorway driving. Could this be the cause of my increased fuel consumption that the engine isn't reaching temperature? What temperature should a 1.8 petrol reach?

I bought a new thermostat to fit yesterday but hjust wondering if there is anything else I should check while I've got it in my workshop tomorrow.

Car seems to run fine apart from beinng thirsty at the moment. I was happy with the 35/36 mpg I was getting before from a 10- year old petrol that owes me nothing.

Exhume.dk · Post by **Exhume.dk** » 31 Jan 2009, 13:21

oxygen sensor ? Changed mine, huge gain in fuel consumption

Water Temp. gauge for the ECU ?

Get a fault code read-out perhaps.

88 centigrade most likely( on catalytic ) but at least 82 centigrade.

hamster · Post by **hamster** » 31 Jan 2009, 13:25

Will change thermostat first and see if that helps. where is the oxygen sensor?

Can't afford to pay for a diagnotsic check at moment!!

MJM · Post by **MJM** » 31 Jan 2009, 14:30

Mine's a 2 litre petrol, just passed it's mot ok. It's the exclusive so probably the heaviest Xantia apart from the v6 and the Activa.

I've just changed the thermostat and coolant and it runs with the gauge needle just above the mark between the 60 and the 90 mark. I've assumed that's about 80 degrees. It's always read that even with 3 different thermostats fitted. It only goes higher when in traffic. Even "making progress" on the motorway doesn't make it run hotter.

On average I get about 33 to the gallon. This time of year it drops to just over 30. Driven gently (boring!) in the summer it will do about 35.
Your consumption is probably due to the current cold weather.

addo · Post by **addo** » 31 Jan 2009, 20:02

In response to the OP, I would suspect oxygen sensor or a restricted catalytic converter. It should do slightly better than 33MPG in cool weather - mine did that figure recently driven enthusiastically on dirt roads, in significant heat!

Thermostat can be checked if you have a reliable thermometer and can improvise a double boiler on the stove. I'd replace the rubber sealing ring when refitting, but reckon the OEM thermostats are pretty good quality and unlikely to be the issue.

Regards, Adam.

vince · Post by **vince** » 01 Feb 2009, 08:58

might seem like a stupid question but when you fill up do you go off the number of litres put in, or by the amount of money? Petrol has risen 5 pence or so around here in the last few days.....= less litres

Post by **myglaren** » 01 Feb 2009, 10:18

The volume of fuel (litres or gallons) as the price is always an arbitrary amount, changes day to day and filling station to filling station.

It is the quantity of fuel consumed to cover a certain distance that are the criteria here, the cost is insignificant but if you record that at the same time you can see how many pence per mile the car costs to use, disregarding repairs, servicing, insurance, tax MOT and other insignificant details

I always ask for a VAT receipt and write the mileage down on it then reset the trip meter. I feed the fuel quantity, price and mileage into a spreadsheet that then gives the MPL, MPG £PM MP£ Average consumption, Grand Average, total miles covered, total fuel costs etc. etc.Then there are other columns for other expenditure including Tax MOT, Servicing, spares etc. - you get the picture.

I'll get my coat - it's the anorak

hamster · Post by **hamster** » 01 Feb 2009, 13:05

is the oxygen sensor the same as the lambda sensor??

if so how do i test it and how expensive are they to replace if required?

thanks

Exhume.dk · Post by **Exhume.dk** » 01 Feb 2009, 13:52

hamster wrote:is the oxygen sensor the same as the lambda sensor??

yes it is

hamster wrote:if so how do i test it and how expensive are they to replace if required?

Try this Clicky

Seen @ 88 £ HERE

_kid_ · Post by **_kid_** » 01 Feb 2009, 15:15

i had a xantia 1996 1.8 16v, the mpg was shocking (do a past posts search), around town it was something like 23mpg (would drop as low as high teens) and it was driven sensibly, on the motorway 33 mpg was about average. Again driven at an indicated 70-80 mph. this was the reason why i got rid of the car.

The mot emissions were always very low (i.e. co was often 0.00% whilst the HC would be around 20 ppm). I changed the service items and stat it made no difference. No codes showing on a lexia machine, so i sold it- was not worth spending anyone more money.

I also changed the lambda sensor as a garage who said it was showing a code- made no difference- why would it- the mot emissions test the lambda anyhow.

if your mot emissions show lambda as ok- i would leave it. If you want to change it eurccarparts and Bosch dealers were the cheapest when i rang around- genuine bosch of course

Kowalski · Post by **Kowalski** » 04 Feb 2009, 17:34

myglaren wrote: I always ask for a VAT receipt and write the mileage down on it then reset the trip meter. I feed the fuel quantity, price and mileage into a spreadsheet that then gives the MPL, MPG £PM MP£ Average consumption, Grand Average, total miles covered, total fuel costs etc. etc.Then there are other columns for other expenditure including Tax MOT, Servicing, spares etc. - you get the picture.

I'll get my coat - it's the anorak

I've got a similar spreadsheet, complete with a graph showing my cost per mile going up over the 5 years I've had the car....

addo · Post by **addo** » 04 Feb 2009, 18:59

Moi, aussi.

I find the accrued total fuel outlay (thousands) the hardest bit to look at!