Hydractive Problem

The sportsuspension seems to maybe work rear but not front. If I pass a speed bumber I can feel the rear end drop after a few meter, after the speed bump but it's still unnormal hard.

Hi Noz

I today swapped the ECU's (in the rain) and guess what - no difference. It still clonks and buzzes when you open the door but no soft suspension. The only significant thing I did notice was that when the solonoid was switched off, there was no clonk, just an absence of buzzing, suggesting as we thought that the valve is in fact not staying open.

Next week, weather permitting, I will try to establish the functioning or otherwise of the diodes and will report my findings.

Peter.N.

Peter, with a derv burner can you play with the electrovalves after you've been for a drive? I find with my petrol cars that once you come to a standstill, the electrovalves are still sensitive to the throttle potentiometer so you can blip the throttle very quickly (hardly making the engine speed increase at all) which makes the ECU move the valves, then count to 3 before you hear another clonk as they move back again.
This also tests the sport switch as the time delay stretches to about 5 seconds when the sport selection is made.

Doing this routine whilst lowering the suspension gives a clear indication whether the valves are working properly as you can feel the centre sphere pressures coming in or out as you get a clear jolt through the suspension.

Not very scientific I know, but it works on my cars.

Hi wirdy

All my derv's have had mechanical fuel injection - I like it that way, so I dont have any engine electronics, I can only control it stationary by opening a door. Having done this when it was working correctly, I know for sure that it isn't now, that and the fact that it rides like a german car!

Peter.N.

Hi Peter

I believe the Hydractive will have a sensor in your throttle pedal (and all other sensors it has) independently of your engine's electronics -it doesn't need any data from the engine-. No?

cheers
George

This post has been edited by jorgy9 on March 15, 2008 09:38 pm

That's the one I meant.....the hydractive 2 throttle pot above the pedal - uses the rate of change of throttle to put the suspension into sports mode and prevent excessive squat under acceleration.

Or maybe Peter had his taken off as he doesn't do over 2500 rpm anyway

Oh thanks! I'm really showing my ignorance here. I know it has sensors in various places but the only ones I know about are the ones that I have met, which is limited to the one on the front anti roll bar, which I had to remove to fit the steering ram pipes.

Peter.N.

P.S. I don't drive as fast as 2500 rpm

Problem solved! I feel rather foolish actually because it was defective diodes in the electrovalves. I fitted the two diodes in the ECU as per Noz's self help file and after a bit of a hiccup, away it went.

I have gained some useful information during the excercise though, firstly how to depressurise the centre spheres and secondly, how to diagnose faulty diodes without getting your hands dirty.

What seems to happen is, or at least what happened in my case, was that the valves were opening briefly and then shutting again, so although I could hear them open and the usual 1000hz whine was present, they were in fact telling me lies and the way you can tell is just by listening.

Park the car somewhere quiet and after a few minutes open a door, if your electronics are working at all, you should hear a 'clunk' followed by the usual whine, shut the door and listen carefully until the valve shuts off, you should hear another 'clunk' and the whine stops. No clunk - the valve hasn't shut because it wasnt open - faulty diode/s. If you do hear the clunk and the suspension hasn't gone soft - centre sphere needs replacing.

If the suspension is working properly, you should have about twice or three times as much movement with the valves open as with them closed.

If you dont fancy taking the ECU apart or are not to good at soldering, one of our number advertises on ebay a box containing the two diodes that can simply be fitted externally.

Another problem solved - I wonder what the next one will be. "You never get bored with an XM"

Peter.N.

...couldn't remember who it was, but then I cant remember anything much

Roy. But I can't remember his number, either

Just a postscript to the saga.

The suspension was fine for a week or so, then a few days ago it went hard again, but only at the front this time. I did my diagnosis trick of listening for the electrovalve opening and shutting - and it was. The only logical thing I could think of was failure of the centre sphere - and it was. tranquility has now been restored.

Peter.N.

I thought I had better just add that my method of depressurising the centre sphere only seems to work if the diodes are u/s.

This post has been edited by Peter.N. on March 29, 2008 05:17 pm

Hi Peter,

Just read your posts. Congratulations. It must be bliss now. Glad to hear you finally got it sorted.

Cheers

noz