Thirsty V6 Xantia

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Ozzie Kuma
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Thirsty V6 Xantia

Post by Ozzie Kuma »

I have been working thru some issues with a V6 I bought a year ago & the only major issue I have left is that it seems VERY thirsty on petrol. It seems to run very well, smooth, very strong acceleration, there does not seem to be any odd problems,..( leaking fuel etc) so I was wondering just what can be done to "tune" a car these days?? A mechanic suggested the vacuum may be out & is planning to put it on a Lexar , I know nothing about such things.
Any hints/ suggestions ?
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Post by addo »

First thing is usually to test compression. At the same time it's possible to evaluate spark plugs.

Weak spark is the usual cause of fuel overconsumption - my 605 has all plug leads open circuit and drinks like a sailor on shore leave. Lexia will show the dwell times of each coil pack, which helps to identify any failed ones.

If you've got a duff coil, jgra1 is shortly to post some stuff over to me - you could perhaps arrange with him to include any small items in the same box.
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Re: Thirsty V6 Xantia

Post by DickieG »

What consumption figures are you getting?
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Re: Thirsty V6 Xantia

Post by jgra1 »

I have a spare coil pack.. I shuold keep it but I dont need to right now..
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Re: Thirsty V6 Xantia

Post by Ozzie Kuma »

plugs etc are fine I think, all look new-ish. Consumption , don't have figures just know it is about 1/3 worse than the VSX I drive. ... shall get some figures.
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Re: Thirsty V6 Xantia

Post by RichardW »

What engine is in the VSX though...???

V6 is usually quoted at around 30mpg average if you're not pottling round town, or giving it some beans. Expect to see <20 if you do that :lol:
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Re: Thirsty V6 Xantia

Post by Mandrake »

Watching this thread with interest :lol:
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Re: Thirsty V6 Xantia

Post by Ozzie Kuma »

Vsx is 2 lt.
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Re: Thirsty V6 Xantia

Post by xantia_v6 »

If I recall correctly, on moving from a 2l VSX auto to a 3l V6, my consumption went from about 35 MPG to about 30 MPG, same driving style, same routes (mostly UK motorway driving at the time).
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Re: Thirsty V6 Xantia

Post by lexi »

The key with V6 autos............keep out of the town.

The short journey and crawling through town or traffic light kills them for fuel.
Early V6 Mondeo and Vectra are the same. Group the journeys and do the long runs.

The Vel will do 30mpg on Motorway but it drops to 17mpg in town. I think in town the Xantia will only do 20mpg.
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Re: Thirsty V6 Xantia

Post by Ozzie Kuma »

Sound like what I suspected is the case, V6 is not a city car. Just as well I have the two of them, long may they keep going. Still does no one have any technical comment on the issue?? are these cars such that nothing can be done to "tune" them?
Just a side issue for those who have owned these two Xantia,VSX & V6, did you notice a big difference in the steering / handling / ride,... my VSX steers like it is on rails & the ride I consider "true citroen" , smooth but firm, superior to the V6. The V6 is very light in the steering a bit "wallowy" unless pushed then it tightens up but the VSX is still superior. I have had the "toe" reset 4 times to different settings , now it is back to factory settings & although I don't think the spheres need it, I am getting them all regassed next week just to make sure it is not them. Thoughts.
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Post by addo »

Suspension bushes.

They wear in sneaky ways; you won't notice it on passive toe setting but on the road they toe out more. This causes more vagueness and extra fuel usage - I was flabbergasted when the toe was reset on mine and it came in 26mm - fuel usage dropped 20%!

Really though, the "tuning" is more a case of watching what's happening with the coil dwell times, looking at the plugs and also checking compression/vacuum.
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Re: Thirsty V6 Xantia

Post by Ozzie Kuma »

( hey mate ) Bushes are fine.... Jason H suggested it may be the vacuum too, taking it to him next week to do his magic.
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Post by addo »

Low vac will be either an air leak into the inlet manifold or throttle body, or low compression on a cylinder (unlikely, but worth checking).

To test the bushes, you can't just pry them as they start to fail well before this method gives results. Try accelerating hard from a rolling start - once you are about 15-20km/h, boot it. If the car pulls to either side you have aged bushes. Test two is at a small, tight roundabout see if the outer wheel seems to change toe when pushing it hard around.

I'm envious of the refurbished spheres - been trying to get my hands on a gassing rig.
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Re: Thirsty V6 Xantia

Post by Mandrake »

Ozzie Kuma wrote: Just a side issue for those who have owned these two Xantia,VSX & V6, did you notice a big difference in the steering / handling / ride,... my VSX steers like it is on rails & the ride I consider "true Citroën" , smooth but firm, superior to the V6. The V6 is very light in the steering a bit "wallowy" unless pushed then it tightens up but the VSX is still superior. I have had the "toe" reset 4 times to different settings , now it is back to factory settings & although I don't think the spheres need it, I am getting them all regassed next week just to make sure it is not them. Thoughts.
I had a 2 litre petrol 8 valve 1997 VSX probably very similar to yours and now have a 1998 V6 Exclusive.

Now that I've fitted new spheres to the V6 the ride and handling is very similar to the VSX. I wouldn't call the V6 wallowy at all.

The steering on the V6 is a bit lighter, however there are some variations in steering feel between different model and year Xantia's, due I believe to slightly different steering racks. (Front tyre size and tread can affect how heavy the steering is too...) Personally I found the steering on my VSX a bit heavy and like the lighter sharper feel of the V6 steering.

I would suggest check the ride height is correct, too high will sometimes make a Xantia feel a bit wallowy, otherwise it all comes down to the spheres that are fitted. My guess would be that the car may have comfort spheres fitted, or the wrong spheres fitted, as the feel of the ride and handling comes 90% from the springing and damping rates of the spheres.

What is the history of the spheres (new, old, regassed etc...) and are they original Citroen or 3rd party ?
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
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