Sticking Hydractive valves?

[Shaolin Twelve]

Hello all,

ever since I have owned my Activa (4 years now), it has had a problem
which I have tried and tried to get to the bottom of with no success, and over the years the problem has become more pronounced.

The problem;

if I go over speed bumps even relatively slowly 15-20mph, or encounter large dips on the motorway, or heavy bumps in general on the road, my
activa goes into solid suspension mode and bounces alarmingly. If I go into higher suspension mode this seems to reset the suspension to soft, but even in higher mode, the same problem happens, and only readjusting (in motion) of the ride height, or a long section of smooth road seems to reset the suspension into the softer mode.

Attempted repairs;

I have replaced a number of spheres (with proper activa ones), pretty sure I did all the fronts and just had 3 left to do on the rear, but as the ones I already did made no difference, and the rear suspension seems to behave itself, I left it at that.

I replaced the main pump in an attempt to rule out pressure.

I replaced the rear Height corrector (which was sticking) and
have attempted to reset the ride height, which is proving to be most troublesome (no pit or ramps available to me). I either get it too low
or too high, or when I get it just right (one finger on the rear, 4 on the front), and put the car through its suspension modes, the rear either
stays high going from top to normal, or the front stays down on the ground whilst the rear is in normal.

I cured a small front activa ram leak using the jubilee clip method, I will attempt CitroJim's method later on for a better looking and permanent solution.

I cleaned the LHM filters (which were clean anyway), and the LHM is good and clean.

Corrected the ns lean (why O why didn't citroen use the same type of adjusters on the suspension control rods as on the roll control rods?)

Fitted a device from Ecrofting, which I bought from ebay, which claims to correct hydractive problems (like overly hard suspension). Is this the same device as Uncle Bucks? The seller had many positive feedbacks, and had a 100% rating have traded for some years.

On checking the advice on this site for Activa buying checks and hydractive checks, I note that a few of the things I thought were faults, are Activa normal behaviour (springing up from low position), side to side shuffle at startup (fine when idling), stop light coming on going from top to low, and back to normal or top again.

My car passed it's MOT last week (thankfully the tester didn't realize it had locked into hard mode), though he did put an advisory about the front anti roll-bar linkages being different.........I did explain to him that it's meant to be like that, but he looked at me like it was my modification. Fortunately, the computer had already warned him that the suspension and brakes can be a bit tricky on this model, so no failure

So has anyone else experienced the same problems with the hydractive system switching into hard mode whilst driving?

Does anyone know a foolproof method of ride height setting, should I do the front first then the rear (I ask as an adjustment on the front affects the rear and vice versa)?


16:40 Sun 21st Nov 2010;

Ok so I just got back from a drive in my activa and now it seems to be working properly.....but there's a bit more to it.

Just after I put up this post, I went out to readjust my suspension, and
(forgive me for this) start stripping my V6. My V6 is being sacrificed to provide electric seats, 10disc cd changer, and every bit I can keep (including engine, gearbox, controls, boxes etc). It's a sad day for me because I really liked this car, but in 2 years I have been unable to get it started, and now I just cannot afford to keep it, so I have decided to strip it, so that I can at a later date, turn my 2.0 litre turbo, into a 3.0 litre V6, manual Activa.

Anyhow. Before I took out the seats from my activa I readjusted the ride height, and got it to 3 fingers on the front, 1 on the rear. I then took a friend to the shops, and although the ride height is now good, the first speed hump (negotiated at 15mph) caused the suspension to start bouncing on the front.

Opening the door whilst driving seemed to bring it back into soft mode over the course of around 15-20 seconds. So there was no change.

When I got back, I removed the seats of both cars, and noticed that the V6 has a control box under the drivers seat carpet, connected with a large red connector (not under the seat, but under the actual carpet). I noticed that my Activa has the connector, but no sign of a control box at
all.

I don't know what this box does on the V6, or why it is not on my Activa, but thinking that it might be related to the electric seats, I fitted it anyway to see what would happen. Well nothing blew, and on discovering that the electric seats needed a plug, the Activa is lacking, I decided to refit the Activa cloth seats whilst I make up some wiring for the V6 donor seats.

I fitted the rear leather seats to the Activa, then called it a day (due to light), and put both front electric leather seats into the boot of the car, and then took my friend home.

Oddly, I noticed that the suspension was now behaving as expected, though still a little hard over pot holes, I read elsewhere that the Activa suspension is harder than other Xantias, and this seems to fit. So after dropping my friend off, I went for a drive involving twisties, bumps, smooth sections and roundabouts. The car behaved itself.

So now my question is, what is it that I fitted or did that made this difference? Is it the mystery box I used from the V6 (The Activa looked like it had never had this fitted), or is there wiring related to the Hydractive system that runs under the carpet which perhaps I disturbed to this positive outcome? I don't know.

Sorry about the length, but I think it pays to be thorough.

[CitroJim]

I'm going to have a long think about all of this . It's too late now and my brain is tired. I've just finished composing the January Xantia Files for the Citroenian magazine.

I have a few thoughts but I can't quite get them into coherent sentences at the moment.

I know what that box is from the V6. It's the cruise control ECU! And there's a thing. I knew the Activa engine has the bracketry for the bellows on the throttle body but I never knew the wiring was in place.

By extension, it may be a relatively easy job to equip yours with cruise

Shame you've had to kill a V6 but if it creates an Activa V6 one day then you're forgiven!


I'll be back later with some thoughts....

[Shaolin Twelve]

Thanks Jim, your input is most desirable. So it's the Cruise-control ECU...hmmmm.....maybe it's just a fluke that fitting that seemed to sort the suspension out (maybe today it will misbehave again, we'll see). It is odd that I have been fiddling and fiddling to sort this problem since the first day I owned this car, then fitting the cruise control ECU seems to do it.

You said that it should be a relatively easy job to fit the cruise control to my activa. This is something I will attempt as it wasn't working on the V6 (kept blowing fuses). It would be nice to have all the V6 goodies on my Activa

I've got to go out in the Activa today, so I'll be sure to let you know if it starts misbehaving again.

Thanks again for your help.

[DickieG]

For me there are a couple of things that need to be checked before you start going too deep, one is to pressure check the four strut and two Hydractive sphere's for pressure as there is always the chance that oner or more may be below the required pressure.

The second thing is to have the suspension ECU accessed by a Lexia to see what faults are recorded as some faults will cause the ECU to go into default firm mode and through experience of Activa's their ECU's are quite sensitive to recorded faults in the ECU affecting how the car drives.

[Shaolin Twelve]

Thanks for the advice DickieG. The spheres are new (although just over a year old now as the car has been sat sorned for over a year), and when in soft mode the suspension is supple and soft.

I shudder to think how much it will cost to connect to a lexia if you are talking about a Citroen garage, and the resulting annoyance when they finally admit they don't know what an Activa is......if it's something else, then please do tell as I think that would be the fastest route to a fix.

So I drove the car today, and it behaved itself right up until I had to negotiate 5 speed humps in succession, and the fault was back. As soon as the front suspension compresses significantly, it seems that both the front and rear hydractive units switch off, and take way too long to switch back on again.

It feels exactly like the suspension spheres are knackered, but when it does go back into soft mode, the ride is smooth, and pushing down on the front and rear shows that the spheres are doing their job. I really don't want to have to buy yet another 10 spheres when the last ones I bought made no difference whatsoever.

It only happens on severe road deformations like speed humps, or deep potholes, or those long dips you get on some motorways which due to speed, compress the suspension more than you would on a decent flat road. Steering the car rapidly from side to side does not appear to cause the problem either.

From my perspective, it appears that the struts are compressing, rebounding once, then the hydractive seems to lock into hard mode. When I say hard, I don't mean the stiffer sporty setting, but hard like it goes when you turn off the car and leave it for 30 seconds. To better illustrate this, there is a particular speed hump near me which unfailingly causes the problem.

It is a harsh approx 1 foot rise onto plateaux about 2 car lengths long, with an equally harsh 1 foot descent. As the car hits the rise, I can feel the suspension absorb the bump, and rebound as you would expect (returns to normal ride height), but then the suspension goes solid, and when you come off the plateaux, it bounces without compressing the suspension. This then seems to keep the suspension hard until the road is smooth enough for the suspension to stop bouncing, at which point the hydractive system goes back into soft mode, and normal damping is resumed.

The five speed humps in succession, really upset the car. The first locked the suspension, and just as it was recovering the second relocked it, by which point the 3rd, 4th, and 5th had the car behaving like it was a caddilac with air jacks. Quite amusing but worrying as hell as I fear seeing the struts coming through the bonnet.

Managed to wire in the Electric leather seats today, and swap an ECU under the passenger seat carpet. Once I had completely removed the wiring harness for the electric seats, I found that it was an easy job to plug it into the harness on the left hand footwell, and now have that working a treat. I don't know what that ECU does, but I thought swapping it might help rule out another ECU from the equation.

[myglaren]

Don't take it to a garage for a Lexia session. It will be in the region of £65-85 and half of them don't know what they are looking at anyway.

Seek out and contact one of the FCF members willing to Lexify your car.
How you reward them is up to you.

Check here for details.

[DickieG]

Reading your last post makes me wonder whether what you're describing is actually normal Xantia behaviour when a negotiating a large undulation such as a hump bridge where the suspension goes rock hard once the suspension has fully extended then takes the weight again on the downside of the hump. This is one of the quirks of Xantia's, every Xantia I've owned which is quite a few of every variety from 1.8's to V6's and Activa's including a couple of them from brand new exhibited this trait, I can also recall What Car mentioning it in one of their road tests on a Xantia.

You might be lucky and be able to listen to the Hydractive ECU switching between soft and firm mode by tuning the radio to 171 LW (not easy on a petrol due to ignition interference) when the suspension switches from soft to firm mode the level of buzzing will reduce. The easiest way to test the switch between modes is to flick the accelerator down/up either when driving or once the car has been driven above 10 mph after which you can carry out the test when stationary.

As Steve mentions get a Lexia session sorted by contacting a member of the forum, if you're ever down my way I'll be more than happy to oblige.

[xantia_v6]

I am surprised that no-one has mentioned the 2 hydraulic faults that (reportedly) cause hydroactive valves to stay closed.

1. Low line pressure (regulator out of adjustment).
2. Weak spring in the valave control block (as found by Mandrake).

I would have thought that the problem here sounds like marginally low line pressure.

[Deanxm]

I would agree, it was the same thing my XM was doing recently, i was only getting 135bar max which i thought was ok, turned out uping it back to 145-175 bar got it riding (braking and steering) like it should.
Hitting the bumps seems to cause the hydractive valve to slam shut and thus reverting back to sports mode for a second or so.
Testing the Activa showed it was managing just 120bar maximum pressure.........

D

[Dommo]

Interesting.. How do you measure (and alter) the system pressure??

[Deanxm]

Here is my experience, its on clubxm.co.uk if your not on there let me know and i could post the guide up in my blog.

D

[Shaolin Twelve]

Thanks for the input

No this is not normal behaviour, when my V6 was running it negotiated the same bumps 'n humps without fuss or locking into hard (not firm) mode. The Xantia 1.9TD VSX I delivered from Birmingham to my friend in London behaved well over bumps.

Imagine your xantia has completely shot suspension spheres, ie no nitrogen in them, totally filled with fluid. That's how hard it gets. Regarding the bounce, imagine putting your xantia in its lowest suspension or highest suspension setting and then trying to drive it, and the bounce is exactly like that.

It's so severe that it is dangerous. It is not switching into firm mode, I can select firm mode and the suspension reacts by being firmer more easily, but even in that mode, the problem occurs, and the results are the same.

I think the lexia of a forum member would be the ideal solution, at least you guys know this car, unlike too many Citroen garages. I shall try and find the nearest and get it tested.

I have no idea how to test the pressure in the system, but following CitroJim's activa buying guide, I note that my Activa's stop light goes out within 20 seconds of starting, and behaves exactly as described for a good car. It is smooth on roads where there are minimal bumps/potholes even if they are numerous. It glides over those bumps without problem, it is the road surfaces which are severe ie deep potholes and speed humps, which really upset it. I can also induce it if I brake very hard. Corners taken hard with potholes are felt, but the suspension instantly resumes soft mode upon exiting

It's like my suspension has three modes, soft, firm, & very very hard with bounce. I've tried the same bumps 'n humps using different gears (to gain higher revs and increase the pressure in the circuits), no difference. My main accumulator ticks at a very slow rate, and not very loud either, which suggests that is ok too.

I will try and tune the radio and find out when the valves are opening and closing (thanks for that bit of useful advice). I also think the spring that was mentioned may be worth a look at to rule out system pressure faults (I can brake and steer without the stop light coming on, though the steering does get a bit heavier).

[CitroJim]

In my absence from this thread, all the angles have been covered

One final thought I have is that the Activa Electrovalve may be holding on and this one works in the opposite way to a normal hydractive electrovalve. basically when off, the Activa system is in "soft" roll correction mode and the Activa Balancing Sphere acts as a spring between the front and rear anti-roll bars. This gives some "give" in the bars and makes them behave like normal anti-roll bars.

When the valve is operated, the valve switches the Balancing Sphere out and the spring between the bars is removed, making them absolutely solid. This is "hard" roll control. In this mode, the suspension will be non-existent.

Low hydraulic pressure will cause a similar behaviour by making the antisink valves close and the security valve close. This will isolate the suspension and the only "give" will be them from the very hard corner spheres. Also, the security valve closing will cause the Activa System to be isolated and closed. This will harden things up as well.

I've seen this first-hand and it can be provoked by starting up, opening the bonnet and pushing up and down on the front repeatedly and with gutso to make the suspension really work. If there is low pressure, a few bouts of this will cause the anti-sink valve to close and the suspension will immediately go rock hard. If you let go when this happens, the front will go up high and stay there for a while until pressure increases when it will likely fall down quite rapidly. This may be accompanied by a shuffle or two as the Activa system again receives pressure.

I've even seen it where the car looses enough pressure to shut the anti-sink vales when just sitting there. It then goes high all on its own and comes back down again when the pressure is restored. It can get itself into a slow oscillation where it will go up, lean, go down, lean back and repeat at minute or so intervals.

The accumulator tick rate is not a good indicator of low line pressure as the ticks will be very few an far between as there may be insufficient pressure available to cut the regulator in. The stop light may well stay off as it switches on when the pressure really is very low.

Have a Lexia session, check the operation of the Activa Electrovalve (difficult) and then if all clear, the system pressure needs to be checked.

The easiest way to check the operation of the Activa Electrovalve is to wire a small LED and series resistor across its supply and have the LED visible from the drivers seat. Go for a drive and watch the LED. It should only flash on very briefly under enthusiastic cornering. If it stays on for a while whilst the fault is present, that is the seat of the problem.

Has the Activa Accumulator been checked 100% good? It's often overlooked, living under the battery tray. Ditto the rear anti-sink sphere. These and the main accumulator make up a trio of accumulators in the Activa and they are critically important, all of them.

[Shaolin Twelve]

Jim you have hit the nail straight on the head, what you describe matches my experiences to a tee. The car was doing all you mentioned when in my friends garage getting ready for it's mot. The reason I was unsure about pressure is that I tried another identical pump with no success. It is possible then that the spheres you mentioned, though new (or so I beleive over a year ago), may be low on performance, though that would mean they must have been on the shelf for some time before I bought them.

Do you know what pressure rated ones I should buy? (the previous purchases had various ratings and I have since lost my diagram of which spheres go where, and what pressures they are).

I have to say a huge thank you to all of you who contributed your knowledge to this problem, I am sure this advice will result in my Activa working like it should. I will let you know the results as soon as I have located some spheres and fitted them. on that note, do you know how to test spheres which have been removed? I have 10 to test (removed a year ago).

Drove the car again today avoiding speed humps, and it handled very well, though slinging it from left to right through a roundabout very hard caused it to go hard very briefly, but rapidly went back to soft.

Thanks again for all your help.

[Deanxm]

From what ive learnt recently the Pressure regulator is the key (mounted on the gearbox bell housing at the front with a sphere on it) they loose spring pressure and no longer hold the supply at between 145-170bar they can be repaired very easily if you have a pressure guage and a way to connect it to the output (smaller) port of the regulator, if not get it checked at a local citroen friendly garage or a member here who may have the gear, a secondhand unit may well be in the same or worse state and the brakes and steering do not give much of a clue to low pressure.
If you cant find an existing one i can do a how to on the subjject as ive taken the relavent photo's.

D