Hard front end on xantia 2.0 vsx 1995

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AndersDK
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Post by AndersDK »

hayden -
As the corner (wheel) spheres has build-in damper blocks - they won't do as the center sphere.
Instead try swap the main accumulator sphere (engine front) with the center sphere.
Even the difference in capacity & initial pressure taken into account - a good/bad sphere is immediately recognised by this swapping :
1) a good main accumulator as center sphere should regain soft suspension.
2) a bad center sphere as main accumulator sphere should give near constant rapid ticking from the regulator.
If it does not show up like this - then you have an electric problem with the control of center sphere block (base) electrovalves.
alexx
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Post by alexx »

I agree with Anders - corner sphere won't do the trick.
Before swapping spheres, check ride height first.
You may also try following experiment (in theory it should work, but I didn't try): switch the engine on and wait the car to stabilise. In the meantime, open the driver's window. Switch the engine off, step out of the car and close the door. Then grab the car at the uppermost edge of the doors (that's why you need window to be open), right under the roof and start shaking the car left-right with it's natural frequency (about 1.5 cycle per sec). The suspension is in soft mode 30 sec after closing the doors and you shouldn't feel much resistance. After that, suspension will switch to hard mode and you should fell much higher resistance. That's because in hard mode left and right suspension cylinders are disconnected, and stiff dampers on corner spheres won't permitt almost any body roll. Pressure in middle sphere (whether high or low) won't have any influence here. But, if there is some problem with hydractive system, causing front of the car to be in hard mode whole of the time, the car will be stiff even first 30 sec and you won't notice any difference (or it will be minor).
hayden2004
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Post by hayden2004 »

ok will swop over the centre sphere and the accum one on sat morning and let you know , also the pump do's not click very offen !!!
mark.rayment
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Post by mark.rayment »

I am also having hard suspension problems on a 96 2.0 VSX. I dont think it is sphere related as it is OK for first few miles. Rear of car also drops about 2 to 3 inches if I stop and hold foot brake on for 20 to 30 seconds. I also can detect little difference between hard and soft modes. Problem slowly getting worse. Car has done 72000 miles
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AndersDK
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Post by AndersDK »

Mark -
I really think you should start out with Citaerobics :
http://citroenz.com/forum/viewtopic.php?t=42
Then post again if problems are consistent - preferrably with a bit more details on observations, service history etc.
hayden2004
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Post by hayden2004 »

ok replaced sphere on near side at the bottom i think its the right one !!!
still the same why unless i have replaced the wrong one the one in the centre of the car has a sticker on it saying acc/brake which looks new unless someone has replaced this one in error before[:(]
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Post by hayden2004 »

whats next god!!!!
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Post by DoubleChevron »

Hmm,
it's time to get all the front spheres (including the new spheres) pressure tested. It's not unknown for a new sphere to be flat. Also I've heard several people mention the ride height. The ride height is CRITICAL for comfort and handling, if it's to high the car will ride badly, if it's to low, it'll be smooth but will bottom out on big bumps in the road.
Then there's onto checking the earth points for the hyperactive suspension. I seem to recall there being a relay that switches the hydractive mode between hard/soft (I'll have to look up the documentation). If you can find this relay, short the bugger forcing the car to stay in soft mode and see what happens :[:o)]
seeya,
Shane L.
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AndersDK
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Post by AndersDK »

I don't know if there in fact is a relay in the circuit feeding the electrovalve.
But I do know the electrovalve is NOT controlled off a +12V feed.
It's controlled by an alternating voltage from the ECU.
This is to keep down the heat dissipation in the electrovalve coil.
A simple go/nogo test on the electrovalve would be to unplug it's connector - then testing the ohm's reading directly on the electrovalve for coil continuity.
I suspect it should read in vicinity of 100 ohms - large tolerance allowed. Obviously it should not read insanely hi (disrupted) - or insanely low (shorted).
BTW : does the connector contact pins and cables look OK - no corrosion or cable chafing ?
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Post by DoubleChevron »

Hmm,
it's bloody near impossible to diagnose these types of problems without the proper documentation. Does the electro-valve need to be hot to engage sports mode or comfort mode[?] If the electro-valve being off causes the car to go into comfort mode, disconnecting it should force the car to go into comfort mode. However as the car switches into sports mode once switched off I'm betting it'll always be in sports mode if you disconnect the electrvalve (otherwise you would drain the battery and cause unnecesary wear on the electro-valve when the cars not being used).
There still should be an 0volt/earth or 12volt feed to activate the middle sphere. With regards to it being a high current carrying circuit or not should be irrelivent as it'll be the 12volt signal that should drive the elecro-valve into comfort mode. Of course if the earth is dodgy none of this will make any difference at all. First thing to do is find and clean the earth point ...
So who has some documentation so we can sort this out rather than trying to 'guess' [:o)]
seeya,
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Post by alexx »

There are two different things.
Sport/Comfort mode means simply if hydractive switch is pressed or not. Depending on that, hydractive ECU constantly alters soft mode (electrovalves engaged - middle spheres connected) and hard mode (electrovalves not engaged - middle spheres disconnected).
When staying locked more than half a minute, suspension gets into hard mode (no A/C on electrovalves). When you unlock the car and open the doors, suspension should go into soft mode. During the drive, it will occasionally switch to hard mode - on sharper bends, accelerations, decelerations and higher vertical movements of the suspension. In sport mode, this will occur more frequently - that's the difference.
If front of the car is still hard after swapping accu and front middle sphere, and accu sphere is known to be good, and ride height is correct (suspension in the middle between bump and rebound stops), hydractive system should be suspected to be constantly in hard mode - in this case, front electrovalve not engaging.
Of course, it's normal that front of the car is not as soft as rear - it should be about twice harder, because of higher weight on the front.
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Post by AndersDK »

Shane :
Start by downloading/reading this document - suspension chapters :
http://www.tramontana.co.hu/citroen/guide.html
Then try out the Czeck CCC site for their Xantia documentation.
Recently they added at least some info on the HA system - on the electro schemata (electrics schematics) page - and BTW '98-on models aircondition (using a TD as example) - a problem you know off locally [;)]
http://citroeny.cz/servis/servis.htm
I've not yet tried out their XM pages for any recent additions on HA systems - you may do that for me [8D]
mark.rayment
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Post by mark.rayment »

Thanks Anders, I have carried out citaerobics. Car takes about 5 mins from low to high levels but also on second cycle, rear of car dropped from high to low instantly. The front dropped as it should do, slowly. It then would only raise at rear after lowering fully . Re establishing normal ride height took about 3 mins with engine reving. Any ideas?
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