Im having a problem with the mpg of the car, it is around 4-5mpg less than would what be expected of the figures of this particular model- 1.8 16v.
I tried all the usual stuff- emissions, brakes, CTS, full service,
A garage has suggested it could be the cambelt which may be off a tooth, his words not mine.
Would this cause a 5mpg drop? Car runs fine otherwise and is mainly town used (80%) , with the occasoinal motorway journey.
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Vehicle details and maintenance history, please.
659.
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Citroen xantia would be my guess looking at some of rip's past postings. However, I'll wait for his confirmation before editing the subject header. ( :whinge mode on: something I wouldn't have to do quite so often if more people actually read and took notice of the sticky messages Tips On Posting To this Forum & Include car make in the subject header - :whinge mode off: )
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yes xantia ,1996, but the question was a general one regarding cambelt and mpg
any ideas anyone?
{Car make / model and mpg problem added to subject header - DD}
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Should add cambelt changed in Jan 02 by main dealer which was around 35,000 miles ago due to a recall, although the car had done 63k by then. No leaks, no oil use etc on the car.
The car has had manufacturers recommended history, and i have given the filters, oil (total 10w 40) and sparks a change.
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it is around 4-5mpg less than would what be expected of the figures of this particular model
The book figures rarely match real life figures as the book figures are calculated under optimum operating conditions.
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I agree with DD.
The official combined MPG figure is supposed to be the closest to what you can expect in the "real world", although most road tests report a 5 mpg or so deficit between what they actually get and what the combined figure says.
Manufacturers tests are as follows:
Urban: An engine started from cold in lab conditions and operated at varying speeds (max 50 km/h, average 19 km/h) over a theoretical "distance" of 4km.
Extra Urban: conducted immediately after the Urban test (so engine is warm) and consists of half "steady speed" driving and half variable speed driving (max 120 km/h) over a distance of 7 km.
Combined is an average of the two, and the one that is often quoted as the "expected" figure.
You don't need to be a scientist to appreciate that these tests completely ignore many of the variables that detrimentally affect fuel consumption in real life. In other words, it's no wonder no car seems to match its quoted figure when driven in the real world.
Cheers
DP
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If its any help, I have a 1999 2ltre 16v petrol Xantia. My driving is 95% cross country to work and back 13 miles each way. Route includes 1 long (2 mile) hill and usual cotswolds undulations. I don't hang about looking at the scenery. The car does between 31 and 33 mpg. It seems to stay in this range winter/summer/aircon/no aircon/fast trip/slow trip.
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Cambelt being a tooth out generally knocks the edge off performance and gives a slightlly lumpy idle - would also expect emissions to be a bit out.
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thanks all, but fuel consumption is bad, round town its around 20mpg, and 30mpg on the motorway @ 70 mph.
i would have thought 25 and 35 would be about right. so something is amiss, less around 2mpg for the air con
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If cambelt was out by a tooth it would be more than mpg affected.
Can't believe a dealer would suggest that idea and then let you drive car without a big advise being given to you. Could be causing all sorts of other problems if it was the case.
But I suspect problem (if any) lies elsewhere.
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Have you ruled out a fuel leak? I'd be expecting MPG well into the 30s on a motorway with a 2.0 litre hatchback. My 1.4 litre Almera gives anything between 40 & 45mpg on a run.
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There was a recent What Car article on the inaccuracies of manufacturers MPG figures. A few were spot-on, many far from the truth.
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Have you ruled out a fuel leak? >>
Ive had a look in the engine where the fuel rail and injectors are and all fine. Also checked and changed the fuel filter. Had a look underneath the car at the fuel hoses but they go under a cover. Can?t see any leaks. Surely a fuel leak on this scale would have a large smell to.
On other forum xantia owners are suggesting low 30s mpg on mixed use.
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rip,
To be honest your consumption doesn't seem too far away from reality to me. I do very little stop/start urban driving and very little motorway driving either.
How are you measuring your consumption? I do tankfull to tankfull using the trip indicator in the car. That is accurate enough for me, I'm not a consumption freak. I know mine's a 2ltr as opposed to your 1,8ltr but the Xantia is quite heavy and I doubt if the engine size makes much difference. It "may" be that the smaller engine is working harder to do the same job.
With fuel injection I would have thought that a leak would show up easily.
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mjm
Consumption is measured over say an average of £100 worth of fuel (not in one go!). I make a percentage adjustment for town or motorway driving, less two mpg for air con if its on. currently 80% of my diving is town
Like is say, i would have thought 25 (town) and 35 (motorway) would be acceptable for the engine.
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According to the handbook,
1,8 16v manual
Urban 23,2 Extra urban 42,2 Combined 32,5.
Your consumption is a little high according to those figures.
I don't know what you can do about it, though, the mixture is controlled by the ecu. Assuming that you have no misfiring, the lambda sensor may be faulty. If so, I would have thought that the management light would be on. An emissions check would probably check this, but I am sorry, I'm not a whiz kid with electronic diagnosis.
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Don't forget though that these figures are measured in a lab with the engine strapped to a bench and not even installed in the car. The actual car is not tested - only the engine by being put through a computer simulation. It does not take into account the kerbweight of the car, additional loads (passengers, luggage etc), aerodynamic variables (roof racks, windows down), tyre pressures, electrical loads on the engine, air-con (if applicable) etc etc.
If you subtract 5 mpg from the combined figure (which more than one magazine article I've read suggests is a reasonably accurate guide, the car should average 27.5 mpg with 50/50 urban and open road use in lab conditions. It's never going to get close to these conditions in the real world.
Cheers
DP
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Many moons ago I hd a Honda stepthru moped OHC via chain that I rebuilt from scratch.
A friend alos bought one but his had an oil leak.
I helped him to rebuild it with new gaskets but as he had 'done a course on mechanics' he knew better than me and set the cam up how he 'thought looked closer' to the marks than I had put it.
We went for a test ride after and he just couldn't keep up with me.
On returning to his house he noticed that his engine was hotter than mine.
After a mug of tea he changed the cam position by the one tooth that I had said was the right setting (I had carefully noted on stripdown the position) and we tried a test ride again.
He kept up with me and the engine was more responsive (with that little power you really noticed the difference)
The point of my story?
If it was one tooth out then I would expect a performance drop (and a lot worse than 5mpg )and overheating.
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A few years ago I owned a Ford Capri 2.0 Ghia Auto that had a cam-belt out by one tooth. Performance was slightly strange, initially torque seemed OK but it seemed to have no power above 2500 rpm. I have bad memories of trying to join the A1 at night on a very tight slip road , on kick down it was hopeless. In desperation I stopped to look under the bonnet for something wrong and noticed that the exhaust manifold was glowing red hot! When I finally found and corrected the problem the power increase was incredible, the economy only changed a bit though.
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