Thanks for all the replies.

George.

Good sugestion although the suspension goes up quickly enough. I would have thought that it would have bled itself through now. The front is also riding hard although not as hard as the back. The valve is obviously opening initally or I wouldn't have had the lifting/depressurising effect.

Techmanagain.

I thought that was quite a eureka moment too, although I was to busy with the problem for me to be enthusiastic about it.

J.H.

Yes, sounds about 1 kc (in old money)

Peter.N.

Hi George

I have just absorbed your previous post about it shouldn't happen. Could it be whatever is making it happen be the problem with my suspension? My previous experience has always been that you cannot depressurise the centre sphere, but this one was definitely depressurised - completely after I think three cycles of opening the door, closing it, allowing the whine to stop and then opening it again.

Answers on a postcard, or preferably here.

Peter.N.

Is it possible that the block has been taken apart and rebuilt incorrectly some time in the past? I assembled one wrong on the Xantia and it worked backwards.

Steve.

It was working perfectly OK until recently, about the time I changed the hydraulic pipe I think, and that' all that's been done. Cant be to sure though as with the comfort spheres it is still giving a reasonable ride - a little better than the average German car!

Peter. N.

Hi Peter

as I said I cannot figure out an answer. Is it possible you had not put the height lever absolutely to "lowest", but almost there? Is it repeatable?

G

Hi G

The main problem is that although the valves 'clunked' and are still buzzing, the suspension is still hard as though the valve is switched off. It makes no difference to the hardness of the suspension whether the valve is buzzing or not. A new centre sphere has been fitted.

We are going away for a few days next week, when I get back I will put a meter on the valves and see what's happening, which is what I should have done in the first place only I've been a bit busy this week.

Peter.N.

The pressure is high enough to lift the suspension quite rapidly, where would it be low?

Peter.N.

Hi peter

The car would still rise if it were not operating at full pressure but the hydractive valve would not be able to open, the hydraulics require something like 170bar but the tyres support the vehicle and they are only running at 2bar max. Although i am no expert on hydraulics by a long way you cannot discount low pressure just because the car will still rise up.
Good luck anyway, hope whatever it is, is cheap

Dean

Hi Dean

While I take your point, I can't think of any reason that the pressure would suddenly have dropped, everything else is functioning as normal. It possibly coincided with the pipe replacement, I wonder if some foreign body has lodged itself in the valve?

I dont think it will be expensive, just consume large ammounts of time. When I come back next week and have finished refitting the bathroom. I will have a proper go at it.

Peter.N.

Hi G

Yes, I would say mine rises in about the same time, you can drive off pretty well straight away. No antisink.

My regulator cuts in much more frequently though, probably less than 10 secs, it always has. I have changed the accumulator, pump,regulator and DV with little effect. The reg and DV were secondhand although clean, I know one came from a low mileage vehicle.

Peter.N.

Hmm difficult to say then, better, as you said, do the electrical checks first to exclude this side of things.

cheers
G

I've got nearley the same problem on my car yesterday. After a short trip downtown (approx 3km), I park my car and leave it for 15 minutes. When I came back and drove away it got stucked in sportmode and I don't now why. Radio XM speaks as normal and the sport suspension bulb in the dashboard lights up if I move the switch. "Radio XM" is reacting a bit faster. The HP is clicking every 30-40 sec. It raises as normal, no green blood but the "buzzing" sound when I open a door has disappeared. Can it be the CPU?

Hi all,

I met Peter tonight and we talked about the possible problems which could lead to these symptoms. The only thing we could come up with is the way in which the ecu signals to the electrovalve. The electrovalve is a simple solenoid. i.e. a current is passed through a coil which magnetises and pulls a pin into the coil against spring pressure. If the coil switches off the magnetic field disappears and the spring returns the pin to the stop position. As with most magnetic coils the magnetic energy required to move the pin from its resting position to the fully open position is, in relative terms, much greater than the energy required to keep the pin in the open position. If the same amount of energy is fed to the coil at all times then it will produce heat and it will consume wasted power. So, the ecu gives the coil a quick burst of 6v dc to open the valve from a standing start. However, the dc quickly stops and is replaced with a PWM (Pulse Width Modulation) signal containing only a fraction of the energy of the dc signal.

What it sounds like is that the quick burst of 6v dc is opening the electrovalve but then when it stops there's no PWM signal to keep it open and the electrovalve closes again. To prove this point a simple swap of the ecu with another known good one should suffice. Peter said he'd try that when he got home later this week. We'll await the results.

Mike,
If the electrovalves do not buzz at all then I think you have failed Solid State Relays in your suspension ecu. These SSR's fail due to overheating caused by the failure of the protection diode in each electrovalve. Please see the electrical section with a description of the cause, the symptoms and the remedy.

cheers

noz