Xantia "snow mode"

sirrah09 · Post by **sirrah09** » 13 Dec 2009, 19:02

I have recently acquired a mint 1998 Xantia V6 . . . I was looking for a 2ltr but this one was just too much of a deal to let go by. The car, which I bought on internet sight unseen, is magnificent and a thorough check by a citroen specialist mechanic has confirmed that there are no issues. On the down side I have the challenge to persuade my eco wife that the fuel economy is not as bad as some ratings would suggest. So far we have achieved 10ltr/100km for mixed driving however on reading my owners manual I noted the snow mode "prevents 1st gear from being engaged and avoids high revolutions" which seems like an excellent economy mode to me. Up till now I have been using a light foot in city driving to keep the revs down to 2000 or less which is sometimes tricky. After reading about snow mode I tried it and it works brilliantly. The car pulls away from start quite easily and revs are 1800 or less all the way to 55km/hr. My question is whther there is any other feature of snow mode that makes its use for city driving on a routine basis a bad idea. I have searched the net and can find nothing.

Post by **xantia_v6** » 13 Dec 2009, 19:21

I don't think you will damage anything through regular sue of snow mode, but I don't think it will do anything to improve your economy.

Firstly, the transmission ECU (in normal map) is tuned to make gear changes that match the maximum efficiency of the engine.

Secondly, starting off in second makes the torque converter work a lot harder, and the extra losses there are likely to be greater than any gain in volumetric efficiency of the engine.

You could try it and report the results.

deian · Post by **deian** » 13 Dec 2009, 20:28

I wouldn't recommend snow mode myself, i've had one of these myself in the past and the fuel economy is surprisingly good for what the engine is coupled to an auto box.

Auto boxes have a long tradition of being bad at fuel economy because of the energy lost as torque converter catches up with the engine, it's the fluid gushing around waiting to lock up, it's like the clutch but it slips smoother because of the fluid.

Nowadays the autoboxes have whats called lock-up mechanisms where the gears lock up to the engine and bypassing the gushing fluid (wasting energy) over a certain speed.

Luckily the autobox on the xantia v6 is the intelligent type with a lockup mechanism and it is also auto-adaptive meaning it will adapt according to how you treat the engine.

Naturally sport mode is NOT economical, it is there to make car go as madly as possible. Snow mode is also not economical, all it does it start in a higher gear, I think 2nd but maybe 3rd (this was the case in a bmw i used to own), so therefore the torque converter will do a lot of work to smooth the flow of energy (torque) from the engine to the wheels without stalling the engine or spinning the wheels (hence the terms snow mode), it smooths the delivery of power to the wheels to prevent spinning.

For direct power delivery, the best mode to use is the normal mode, drive how you like and the box will adapt for economy! This is what I would recommend. Don't worry about the power you feel in normal mode, it is nice and meant to be like that, slowing that delivery down via snow mode is not ideal for economy. FYI the gearbox has 6 normal adaptive modes it will choose for economy based on your driving style.

Hope that helps. Nice car isn't it. Don't waste the sport mode too, use if when your alone or something

Post by **CitroJim** » 13 Dec 2009, 20:33

Welcome to the world of V6 ownership and to the forum sirrah

Wonderful cars. There can't be many in New Zealand!

I have nothing to add to what xantia_v6 has said but a perusal of the 4HP20 manual might reveal something specific but in all my readings of it, I've not seen anything significant about snow mode...

The V6, for the record, is rather good on the economy front when compared against some other 3 litre cars

keeop away from the sport button and try tokeep it in the most economical map and it'll repay you.

A tip when running through urban 50km/h spped limits is to acclerate just above 50km/h until the 'box changes into third and then gently drop the speed back. She'll then stay in third rather than dropping back to second.

Post by **CitroJim** » 13 Dec 2009, 20:34

Sorry Dei, we clashed a bit there

Both typing at the same time. You clearly type faster than me and make more sense

Stempy · Post by **Stempy** » 13 Dec 2009, 22:06

Or you could just pull two spark plugs out

AbangCorp · Post by **AbangCorp** » 14 Dec 2009, 07:40

no lah, shakey
not economical at all

Post by **CitroJim** » 14 Dec 2009, 07:53

Stempy wrote:Or you could just pull two spark plugs out

I experienced a 6 running on 4 when my ignition coil failed.

They loose an awful lot of power and don't run nicely at all

sirrah09 · Post by **sirrah09** » 14 Dec 2009, 08:02

Thanks for the helpful replies. I might just leave it for now and practice getting the best out of auto adaptive system. I will try your technique Citro Jim.

citronut · Post by **citronut** » 14 Dec 2009, 08:23

Stempy wrote
"Or you could just pull two spark plugs out"

or just tie a knot in the fuel line, not to tight though TEA HE

regards malcolm

Post by **xantia_v6** » 14 Dec 2009, 18:33

I forgot to say welcome,

and I come from Christchurch (NZ), but have been an economic refugee in the UK for about 10 years.

I didn't realise that V6 Xantias made it to NZ, when I was in NZ, the available range was quite limited.

Is your V6 a Mk2? It should be, but you never know how long it takes anything to get to NZ.

sirrah09 · Post by **sirrah09** » 15 Dec 2009, 09:50

Yes it is a MKII but does not have cruise control nor is there any reference to auto adaptive transmission in the owners manual so I am not sure it has it. I think the NZ models were sourced from Singapore in those days but I could be wrong.

Post by **CitroJim** » 15 Dec 2009, 10:08

All V6s have the ZF 4HP20 gearbox and the fact it has a sport and snow button means it is ECU controlled and therefore auto-adaptive.

The handbook only makes vague reference to it.

sirrah09 · Post by **sirrah09** » 16 Dec 2009, 05:27

Its a pity that the auto adaptive thingy doesnt have a driver selection option or better still, given Citroens flair for innovation, voice activation so you could just turn on the ignition and croon "eeeaasy boy" or shout "go baby go!!" and Bob's your uncle