Hydractive Repair Kit

Post by **CitroJim** » 22 Apr 2007, 22:52

Another interesting point raised in the French document from DickieG is that the authour of the document recommended the use of a Schottky diode.

These have an avalanche reverse breakdown characteristic which effectively means they put a bigger and better short circuit across the electrovalve coil and thus absorb the back EMF generated more effectively than a standard silicon diode of the 1N400x family can.

deian · Post by **deian** » 22 Apr 2007, 22:54

AndersDK wrote: KISS = Keep It Simple Simon

He comes out with the most comical stuff sometimes, it's brilliant how simon and anders work together, technically they both know a lot, and have personal views and differing techniques on many subjects, but they never fall out and flame each other. It shows how professional this forum is compared to some others i have seen!! Excellent stuff guys. Where were we...

AndersDK · Post by **AndersDK** » 22 Apr 2007, 23:38

I'm not clutching to a straw trying to explain me out of the fact, that it may not be the spheres at fault.

- but ...

By far the spheres are still the most common cause to softness/firmness problems in a hydropneumatic suspension.
I'm certainly not satisfied with the statement saying the spheres are new and/or replaced within the last year or so. It does not warrant anything against bad or wrong spheres.

1) It is a fact that good front spheres will still compress noticeable when test loaded in hard mode, provided the suspension is at normal height. If in soft mode it will of course sink like a compressed marshmellow, compared to hard mode. The narrow center orifice in the hydractive wheel spheres will make for a slow descent when suspension is test loaded in hard mode.

2) As we are talking front spheres its not that hard to access these and wipe them clean for a positive printed part no identification. This is needed for further discussion on the problem. Also if the spheres were the brand new ones, or the economy recon/regas types.
A receipt on purchase is no good. You may easily have beenn given a completely different type than stated on your receipt. Same goes with the box. The content may be different than any stamps/labels on the box.

3) was the hydractive center sphere replaced with the wheel spheres, or dont you have any history on the hydractive center sphere ?
Bit harder with the center hydractive sphere identification because of its location, but it will definately enlighten the discussion.

4)
a) Was the problem evident from the day you replaced the spheres
b) has the problem showed up now and then for some time, and now has become permanent ?

5) you have not positively indicated you have done extensive Citaerobics ?

CypherPunk · Post by **CypherPunk** » 23 Apr 2007, 00:12

Hi Anders,

The front of the car was stiff when I bought it, I knew that this could be a problem as it was fitted with Hydractive 2, but as the rest of the car was in good condition, and the price was right, I risked it and bought the car anyway.

Probably a month or so after I purchased the car I replaced the two front spheres and the front centre sphere, this improved the ride somewhat, but it still wasn’t as good as my previous Xantia (1997 1.8 LX). While I was underneath the car I had someone open the door to switch between hard and soft mode, as I could hear the electrovalve click I decided it must be working and that Hydractive suspension must just be stiffer than normal hydropneumatic suspension.

While I was changing the front centre sphere I noticed that it was very rusty, it was also a slightly different shape than the new sphere, instead of being totally spherical it was slightly flat in the middle. I’m fairly sure I double checked the part number before fitting the new sphere, however it was a while ago so I’m not completely certain.

A few weeks ago I decided to replace the front and back accumulator spheres as they were also quite old and the regulator ticking had become more frequent, I decided that while I had the car jacked up I might as well replace the rear spheres and the rear centre sphere. After changing the spheres I had a bit of a problem with the front of the car oscillating, but after depressurising and re-pressurising the suspension system the problem went away. Changing the rear sphere again improved the ride slightly, the back of the car seemed slightly stiffer and harder to push down, but it now rides over bumps much better.

I always perform citaerobics once a month and must have spent a good 20-30 minutes moving the car from height to low when I last changed the spheres.

All the spheres fitted to the car have been purchased from GSF and are brand new, not re-gassed spheres.

Mandrake · Post by **Mandrake** » 23 Apr 2007, 00:42

CypherPunk wrote:
I test like this: Switch off engine, open and close door and listen for clicks, bounce each end in turn continually whilst listening for the click of the electrovalve releasing back into hard mode after 30s and feeling the difference in bouncing as it does. If you bounce once or twice in soft mode and then wait and bounce after the switch you may not feel the change, alweays best to bounce continually and then you can really feel the change on the transition from soft to hard.
I've just tried this test, and, to my annoyance, I could definitely feel the car switch into hard mode on the front, it's very slight but it’s definitely switching properly.

When you say you could feel it switch - do you mean that you noticed a difference in the compressability of the suspension, or do you mean that you could feel/hear the "click" from the electrovalve ?

Theres one further "gotcha" that I forgot to bring up - if the diode is faulty (depending on whether it is completely open circuit or not) the electrovalve can still click - and switch to soft mode - for exactly half a second!

Normal operation is that full 12v DC is applied for half a second, during each hard to soft mode transition - this gives the electrovalve a good solid shove to ensure it switches reliably.

Then after half a second it reverts to a pulse width modulated signal with an RMS of about 3 volts which is enough to hold the electrovalve engaged without overheating it. (But not enough to activate it initially)

The gotcha is that that initial 0.5 seconds of 12v activation will still work even if the diode is missing or faulty, but as soon as the ECU tries to apply the PWM signal it detects a fault and shuts down the output for one minute. (And then tries again)

So a faulty diode often results in a brief burst of soft mode, accompanied by a kind of double-click, then back to hard mode again for the majority of the time.

One way you could check for this is the following - doors all closed and engine idling set the height to "intermediate" height (one notch back from normal ride height) and let the car lift, then turn off the key. If you get a sudden drop at the front when you do this, you have a faulty diode.

(In fact if you ever get an abrupt jump or drop in height when turning the key on or off after the car has been raised or lowered, the diode is faulty)

Any other ideas ?

Yes,

Were you able to try powering the electrovalve directly for a few seconds as I suggested in a previous message ? You'd want to be careful to get the polarity right, but it would tell you in a matter of minutes whether this is the problem or not...

Regards,
Simon

Mandrake · Post by **Mandrake** » 23 Apr 2007, 01:15

DickieG wrote:I swapped ECU's but that made no difference. When I tuned the radio to 171 LW to listen to the switching points (not so easy on petrol cars due to interferance) on both Activa's the switching would stop after a few minutes, and be replaced by a brief periodic pulse (this was obviously the ECU trying to reset the diodes in the blocks).

Thats pretty much what mine would do - except I don't have LW on my radio so I was monitoring it with an LED.

So did yours do this on a fairly consistent basis ? I can only assume that engine bay heat triggered the fault and when it cooled down the fault went away again. Nasty!

if anyone can read French, it's also shown on the following link http://activaclubfrance.free.fr/Entreti ... liques.pdf

Brilliant!!

*Looks around expectantly for Clogzz*

Seriously though, is it worth contacting the author of that document and seeing if they can translate it to english ? (or at least getting permission to do so) as it looks like it encapsulates the entire problem and solution very neatly - and has a great explanation of how the electrovalves work with diagrams.

I can only see this problem becoming more and more common as the cars age, and it could very well be a design flaw like the strut tops where its not a matter of IF it will fail, but rather WHEN it will fail.

Regards,
Simon

Mandrake · Post by **Mandrake** » 23 Apr 2007, 01:44

citrojim wrote: I've just bounced mine in hard mode, pushing on the edge of the wing, this 10 stone weakling can only get about 3/4" movement pushing with all his might

Opps... I'd recommend NOT bouncing the suspension by pushing on the front wing (especially in the hard mode) as its very easy to put ripples in the wing. How do I know this ? Don't ask.

Pushing on the plastic bumper isn't that great either as it's not particularly sturdy for vertical loads - I'd suggest opening the bonnet and pushing on the tray above the headlights...

Regards,
Simon

Post by **CitroJim** » 23 Apr 2007, 05:45

Mandrake wrote:Opps... I'd recommend NOT bouncing the suspension by pushing on the front wing (especially in the hard mode) as its very easy to put ripples in the wing. How do I know this ? Don't ask.

Regards,
Simon

I know, mine already has

I initially wondered how they got there as well

Normally, I do push on the slam panel but for the forum, I tried the wing so that I could confirm I was not compressing the tyre.

As regards translation Simon, no real need really. Schoolboy French and help from a on-line translator gets the essence of the document quite well. Better, in my mind, would be for you to write a very similar paper for us

A distallation perhaps of all your knowledge presently distributed over many, many threads in this forum.

AndersDK · Post by **AndersDK** » 23 Apr 2007, 13:55

citrojim wrote:
Mandrake wrote:Opps... I'd recommend NOT bouncing the suspension by pushing on the front wing (especially in the hard mode) as its very easy to put ripples in the wing. How do I know this ? Don't ask.

Regards,
Simon
I know, mine already has I initially wondered how they got there as well

Normally, I do push on the slam panel but for the forum, I tried the wing so that I could confirm I was not compressing the tyre.

As regards translation Simon, no real need really. Schoolboy French and help from a on-line translator gets the essence of the document quite well. Better, in my mind, would be for you to write a very similar paper for us A distallation perhaps of all your knowledge presently distributed over many, many threads in this forum.

... in french language please

DickieG · Post by **DickieG** » 23 Apr 2007, 20:41

Mandrake wrote:
DickieG wrote:I swapped ECU's but that made no difference. When I tuned the radio to 171 LW to listen to the switching points (not so easy on petrol cars due to interferance) on both Activa's the switching would stop after a few minutes, and be replaced by a brief periodic pulse (this was obviously the ECU trying to reset the diodes in the blocks).
Thats pretty much what mine would do - except I don't have LW on my radio so I was monitoring it with an LED.

So did yours do this on a fairly consistent basis ?

Yes, it appeared that as soon as the engine was running (and the car had exceeded the required 5 km/h to activate the system) that the Hydractive would fail to operate correctly. I wonder whether higher voltage generated from the alternator has something to do with it as the fault would occur with a cold engine. Both Activa's displayed the same symptoms.

CypherPunk · Post by **CypherPunk** » 29 Apr 2007, 14:25

Quick update, I’ve fitted the Hydractive repair kit this morning, and I’m very impressed. The front of the car now switches into soft mode again and while I’ve only taken the car for a quick trip to the shops I can definitely feel the difference when driving over potholes etc

Thanks for everyone's help.

Mandrake · Post by **Mandrake** » 30 Apr 2007, 00:01

CypherPunk wrote:Quick update, I’ve fitted the Hydractive repair kit this morning, and I’m very impressed. The front of the car now switches into soft mode again and while I’ve only taken the car for a quick trip to the shops I can definitely feel the difference when driving over potholes etc

Thanks for everyone's help.

Hey thats great news...

Keep us informed after you've had more chance to drive the car.

Looks like the guy making those kits has found himself a little cottage industry

(not everyone has the skills or time to do the modification manually!)

Regards,
Simon

CypherPunk · Post by **CypherPunk** » 30 Apr 2007, 23:13

Hey thats great news... Smile

Keep us informed after you've had more chance to drive the car.

Looks like the guy making those kits has found himself a little cottage industry Laughing (not everyone has the skills or time to do the modification manually!)

Well I've clocked up quite a few miles in the car today, and the ride is definitely much better than before, you don't notice how bad the ride is until you manage the fix the problem. The biggest difference I've noticed was when I was driving slowly in traffic, before the car used to bump over every single little imperfection on the road, now it just glides over all but the biggest bumps.

I remember why I loved my old Xantia so much, that magic carpet ride. I was pretty sceptical of the benefits of Hydractive 2, but it’s definitely the best of both worlds, soft suspension while you’re cruising and sporty suspension when you’re making progress. I’d almost be temped by an Activa now, if it didn’t mean giving up that lovely V6 engine.

It’s taken me six months, but I’ve finally managed to iron out all the annoying little problems with the car, although saying that, I’m sure something else will break now.

Mandrake · Post by **Mandrake** » 01 May 2007, 00:03

By all accounts the ride quality of an Activa is quite a bit worse than Hydractive 2 (probably due to the movement friction of the anti-roll rams) so unless you REALLY need zero roll handling Hydractive 2 is probably the best compromise. (And you get to keep the V6

)

Regards,
Simon

Post by **CitroJim** » 01 May 2007, 07:41

Mandrake wrote:By all accounts the ride quality of an Activa is quite a bit worse than Hydractive 2 (probably due to the movement friction of the anti-roll rams) so unless you REALLY need zero roll handling Hydractive 2 is probably the best compromise. (And you get to keep the V6 )

Regards,
Simon

Yes, you are correct there Simon

The Activa is an excellent handler but it certainly pays for it in ride quality. In fact, if you did not know, you'd be forgiven for thinking it has conventional steel springs

You also know very quickly if the Hydractive electrovalves are playing up

Having said that though, ride in a steel sprung car of equal ability and you soon feel the difference. There is no doubt the Activa is optimised for outright handling and finds its niche in travelling at great speed between two points on relatively good but twisty roads. It's ride quality deficiencies show up most on poorly surfaced town roads at low speed. Under these conditions, it picks up every irregularity going. At speed it smooths out nicely and falls perfectly into its refined GT mile-muncher role.

Citroen lost a coup with the Activa. Although the 2.0 CT engine has plenty of grunt and moves the heavy Xantia with great swiftness and aplomb, the handling and brakes can cope with much more power. A really highly tuned engine in excess of 200BHP would have been very interesting