Tweaking aouto gearbox Xantia V6

sirrah09 · Post by **sirrah09** » 01 Feb 2010, 10:17

Has anyone had experience with changing the configuration of the auto gearbox of a V6 Xantia.

In order to trigger lockup on mine I have to take the road speed up to about 64km/h at which point the revs drop from 1800 to 1300. If I reduce the indicated speed to 55km/h (50km/hr actual) the revs drop to 1100 but it is very difficult to stop it from unlocking and going up to 1500.

My 93 Honda civic has a similar system but goes into "lockup" at around 50km/hr and stays there.

Would love to change my Xantia to same and improve urban fuel economy.

Post by **CitroJim** » 01 Feb 2010, 10:29

sirrah09 wrote:Has anyone had experience with changing the configuration of the auto gearbox of a V6 Xantia.

Only accidentially

I once rebuilt a V6 4HP20 with gearsets that originated from a 4HP20 fitted to a 2.2HDi 406. The gear ratios were well different and the ECU became very unhappy indeed.

In theory, I'm sure what you wish could be done but it will involve tweaking the ECU and modifying its gearchange laws. This can't be done at all easily and not using a Lexia.

It would needs someone very clever to be able to access the ECU at machine code level, reverse-engineer it and write new laws to it...

Mine seems to lock up a tad earlier than yours and stays locked at 50 km/h if I'm gentle with it.

I wonder if a gearbox/ECU reinitialisation might help. This will reset all the auto adaptive paramaters and force the ECU to re-learn the gearbox characteristics. A Lexia diagnostic machine is needed to perform this task and there is no other way (that I know of) to achieve it.

Us Poms find our V6s pretty frugal (relatively) when running around town...

lexi · Post by **lexi** » 01 Feb 2010, 10:33

Don`t know. The Civic is a different animal isn`t it? Older school box with no mapping etc. I had a Jatco box that I put a switch on from the ECU to the lock up solenoid. I could then lock up from second gear

.

Jim or V6 will know..........they have had the bits of them in their grubby hands

edit: I`ve posted at same time as you Jim!

lexi · Post by **lexi** » 01 Feb 2010, 10:40

I meant to ask Sirrah. How's your V6 running around in the heat over there?. They do generate heat. What are the indicated gearbox temps?

sirrah09 · Post by **sirrah09** » 02 Feb 2010, 05:39

Lexi . . . I do not have a gearbox temp gauge but the water temp seldom gets over 90. Having said that I have been amazed at how much heat the engine generates which is particulary noticeable when I open the drivers door with the motor running and become enveloped in a wave of hot air from under the body. Spose thats normal?

Jim ... I think a reset would be a good idea as the auto seems, only occassionaly mind, to go a bit crazyand whizz up to 3000rpm when I am quietly accelerating up to 50kph. a bit of a blip on the pedal seems to correct it. I finally found out about these Lexia gizmos last night. . . I wonder if anyone in auckland has one.

I may seem a bit obsessive about this fuel economy thing but my gorgeous, ecofriendly, wife tolerates my indulging in the pleasures of a V6 on the basis that I have assured her it can do better than 10 litres / 100km around town. So far I have been struggling clocking about 10.6.

Hey lexi my little 4wd shuttle is the epitome of cutting edge motoring circa 1993. It is going strong at 280,000km and I cannot bear to part with it. We use it as a town truck (nearly as good at the job as the 1015 GS break I owned in the 70's) The bodywork is pretty battered tho and Alicia is really glad to be able to take the Xantia to her high school reunion garden parties.

Post by **xantia_v6** » 02 Feb 2010, 06:34

I have been trying to think of a way to get you a bit more economy, but these computer controlled engines and transmissions don't seem to give many options.

Have you considered an LPG or CNG conversion?

Maybe the best compromise is to drive it 10% less?

Post by **CitroJim** » 02 Feb 2010, 06:53

lexi wrote:I had a Jatco box that I put a switch on from the ECU to the lock up solenoid. I could then lock up from second gear

Sadly, on the 4HP20, there is no lock up solenoid as such and the lockup is fully ECU controlled to the extent that it's not simply on or off. It has a third mode, piloted, that allows limited slip.

I find that with judicious use of speed and throttle, I can get mine into third gear quite quickly at 50km/h and with correspondingly low revs and what appears to be a fairly firm torque converter.

Sid_the_Squid · Post by **Sid_the_Squid** » 02 Feb 2010, 09:44

Giving this a try on my way home last night, I'm of the opinion that it is a question of gear ratios, the V6 is more of a motorway cruiser, this is reflected in the gearing ratios being quite long, 4th gear is quite high, bear in mind this car can do 220kph, as thus I don't think it will be possible to engage 4th at full lockup at speeds as low as 50kph, as the rev's would simply be to low to sustain (sub 1000rpm). I believe it gets close to full lockup at 60~70kph that's probably your best economy zone. I suspect your Civic can achieve full lockup at lower speed because of its closer ratio gearbox.
Money wise LPG is a good money saver, although would be hard to find space to fit on a V6, eco wise I don't know if it is any 'better' as you'll actually be burning more fuel, just a different sort.

addo · Post by **addo** » 02 Feb 2010, 10:04

I suspect you could actually wind a V6 Xantia "off the clock" if the roads were right. At 190, the four still feels like there's plenty to give but the front gets lighter than I'm happy about. So - the six ought to trounce it.

citroenxm · Post by **citroenxm** » 02 Feb 2010, 10:16

Sid_the_Squid wrote:Giving this a try on my way home last night, I'm of the opinion that it is a question of gear ratios, the V6 is more of a motorway cruiser, this is reflected in the gearing ratios being quite long, 4th gear is quite high, bear in mind this car can do 220kph, as thus I don't think it will be possible to engage 4th at full lockup at speeds as low as 50kph, as the rev's would simply be to low to sustain (sub 1000rpm). I believe it gets close to full lockup at 60~70kph that's probably your best economy zone. I suspect your Civic can achieve full lockup at lower speed because of its closer ratio gearbox.
Money wise LPG is a good money saver, although would be hard to find space to fit on a V6, eco wise I don't know if it is any 'better' as you'll actually be burning more fuel, just a different sort.

Sid,

Why did you quote the speeds in KPH? Most of us, but I realise not all, will be in MPH reading this..

Just curious thats all.

Paul

Sid_the_Squid · Post by **Sid_the_Squid** » 02 Feb 2010, 10:55

Really Paul, this entire thread is using kph, being as the original post is from NZ, expected a sharp guy like you to notice that

lexi · Post by **lexi** » 02 Feb 2010, 11:07

Thing is Paul........ Sirrah is working in KPH ....and litres per 100

V6 definately has long legs. I am driving Prelude auto as well and the gearing is lower. Obviously the V6 ratios are to suit that massive torque and the sports mode is there if you want it.

Yeah heat on the V6

I`ve felt that when you open the door. OR under the car when fans come on!! Gearbox oil sometimes gets to about 90 which is halfway.......usually 70 (about 1/3rd up the gauge).

Post by **CitroJim** » 02 Feb 2010, 11:59

We're now working in kp/h in readiness for whe the UK switches over. It's got to happen soon

lexi wrote: Yeah heat on the V6 I`ve felt that when you open the door. OR under the car when fans come on!!

That's in part due to the huge cat on the car. Looks more like and oil drum than a cat..

A lot is coming from the engine bay and it then becomes clear why the gearbox cooks and the wiring ends up brittle!

90c for oil is OK. Really get enthusiastic in the heat of summer and you'll get it above that easily

lexi · Post by **lexi** » 02 Feb 2010, 12:37

Interesting. All those smaller saloon size V6 of that Genre are the same with heat. Vectra V6 is similar. Everything is tight

Components will fail quicker in that heat.....inevitable.........but pleasurable

Post by **xantia_v6** » 02 Feb 2010, 17:47

Sid_the_Squid wrote: Money wise LPG is a good money saver, although would be hard to find space to fit on a V6, eco wise I don't know if it is any 'better' as you'll actually be burning more fuel, just a different sort.

Admittedly an XM, not a Xantia, but the neatest es9j4 LPG installation I have seen:

Actually the installion (perhaps complete with engine?) appears to be for sale

A modern LPG installation may actually be more efficient than petrol (especially the stuff available in NZ) because it has a higher octane rating, so the engine management can run more ignition advance without detecting knock.

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Tweaking aouto gearbox Xantia V6

Tweaking aouto gearbox Xantia V6

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