HELP! Air Suspension keeps raising itself up and Alarm keeps going off randomly

[james8whippy]

Hey Guys and Girls,

Having a few issues with the X whether all the problems are related or it's a coincidence I am not sure.

Problem number 1: It all started when I went away in May to the US for a month and I came back to a flat battery which is fair enough as the car had been sitting for a while. I charged it and then it kept going flat over night. First thing I thought to try was removing the blower fuses as I remember in my old E46 that they suffer from the faulty Final Stage Resistor (hedgehog). This stopped it going flat!! so a week went by and it didn't go flat once but I didn't have any AC though but not that it really mattered with our summer in the UK

Then came problem number 2: The alarm keeps going off randomly. I have been pressing the lock button twice and this stops this for the time being.
Before I went out and bought a new FSR(Hedgehog) I needed to go on a long drive and needed the AC so put the fuses back in. I forgot to take them out but funny enough for a couple of weeks now it hasn't gone flat once which is strange but I'm not complaining.
So I thought result problem number 1 resolved! ......... well for now anway.

Problem number 2 the alarm is still going off randomly when pressing the button once. It's not a big deal pressing the button twice but I think it may turn off alarm.. not sure?? so hopefully somebody could give me some ideas what it could be? I have read that the bonnet sensor is a common fault so will try unplugging that tonight to see if it stops.

OK now for the most annoying recent problem number 3.
If I lock the car over night the air suspension will raise the back of the car 20ft in the air (well not quite but it feels like that). I have the 4.6is so it only has the rear air suspension fitted. When its raised up it is literally un-drivable as the ride is soooo hard and bouncy. Even when driving it for a bit it doesn't seem to lower itself back down.

The only way I have found to lower it back down is to plug it into my laptop and use the INPA software and manually adjust it on there. So then it's fine for a random amount of time maybe a day maybe two and then the morning I come out again and it's rised up!

I get the odd occasional "Self Level Suspension Inact" message randomly but have always got that since I've had the car so never thought anything of it. I think it's generally my fault when I get it as it's when I'm in a rush and don't give it a chance to do all the checks when the ignition first turns on before cranking it.

So as it stands at the moment I have lowered it down manually on laptop with INPA and have removed the two 7.5A & 30A fuses from the boot fuse box. This should hopefully keep it down.

Going forward though I would like to fix this issue.

Any ideas to what it could be? maybe a sensor or something?

I have read a lot of horror stories from people who have problems with the Air Suspension but their symptoms are normally the total opposite to mine as their's normally sag low and won't raise up.

I know my compressor is working OK as I can hear it and I think the airbags are OK as it will hold the car in the air for days if not longer so hopefully no leaks there.


Any ideas would be very appreciated!

Thanks
James

[Black X5]

I'd say its one of the level sensors.  You should be able to check the voltage reading from each one through INPA.  You've done the right thing removing the fuses- no self levelling function but at least your not jacked up.

Put the fuses back in and get it on the laptop.  If on the off chance the car is behaving when you put the fuses back in- use a trolley jack to raise the car and look for the voltage change. This would in most cases highlight the duff sensor.

[Horizon]

hi there
I work with compressed air equipment and pneumatics.
I come accross alsorts of pneumatic problems, one problem that is quite common is air cylinder creeping, which is caused by vave blocks weeping air past the seats IE a vave block can be an electrically operated selenoid valve usually a3 or5 way block, when the selenoid is powered the valve will open and let the pressurised air from the air reciever/tank pass through the valve to the air cylinder, or airbag in this case. If the plunger in the valveblock does not seat properly to close off the supply of compressed air ( allowing a very small amount to leak past into the cylinder/ airbag over an extended period of time, the airbag will be filled to its maximum travel.
You then reset the ride height with the laptop, so emptying some air out of the airbag via the valveblock.
then when the car is stood again over time the bags will inflate again. If you drive the car the ride height will be adjusted via operation of the sensors/valveblock
This is just a thought as ive not looked at how the X5 air susspension is controlled, but have experience with HGV air suspension.

[james8whippy]

Hi Guys,

Thanks for your replies.

I have looked for the voltage function on INPA but can't see it, I can only find the sensors height in mm and it ranges from -128mm to 128mm with a bar that moves for each sensor.

When it jacked itself up I plugged the laptop in to have a look and the left sensor was showing 86mm and the right was showing 53mm so it looks as if it wasn't sitting level.
I stood on the side steps on the drivers side and this made the right sensor go down to 44mm and the left sensor go up to 90mm which I would assume is right as I am putting 12.5 stone of weight on the RH side of the car which would cause the left side to pivot up.
I have now lowered the car back down to 0mm not sure if that is the correct normal height but as this was in the middle of the bar on screen and looks about right from in the wheel arch if not maybe a little too low I guessed it at that.

So the question is as I am getting readings from the sensors does this mean they are OK?

Horizon - So you think it could possibly be the valveblock would this be like a valve in-between the air storage tanks in the boot and the pipes that connect to the airbags on the axel?

The strangest thing about mine is when it jacks itself up the car is turned off and locked. I would of thought the compressor would need power to start up but as the ignition is off and the car is asleep I thought this cuts off all power to devices?

Probably got this totally wrong but from my understanding of your post you say it could be the valveblock that is letting the air go from the storage tanks in the boot. I really don't know much about how much air would be needed to fully inflate the airbag but I think the storage tanks in the boot are very small so even if all the air was dumped from there into the airbags I don't know if this would be enough to inflate them fully.... again I really don't know what I'm talking about so please correct me if I am wrong.

Thanks
James 

[Horizon]

HI there.
I have not looked at a diagram of the X5 air suspension, but  there must be a valve that lets air in and out of the airbags. to inflate, a valve must open between the air reciever /tank between the compressor and the airbag, and to let air out of the airbag the valve will switch between the airbag and atmosphere.
This is what we call a 3 way valve. if the seal on the "exhaust side" of the 3 way vave was allowing air to pass over its seat, the bags would deflate overnight, the same as having a small leak on an airbag.
If the valve seat on the possitive "fill side" of the system was allowing the compressed air from the small air receiver in the boot to creap passed it and over inflate the airbags overnight.
As example over the ability of the air in air receiver to overinflate the bags, look at 4.8 where you can alter the ride height. If you move the swich to high, the air reciever will inflate the airbabs instantly, and in the down possition will dump air from the bags to lower the suspension.
This switching between up and down is done via the valve block. When the desired height is obtained the vave will seal so not allowing any movement in air either in or out of the airbags, so maintaining the ride height.
Why this problem only occurs on certain nights may be is that the valve may seat properly some days and not others.

[X5Sport]

This is a link to the BMW Training for Dealers notes for how the air susp system actually works.  There might be something of use buried in here of use perhaps?

[shadrack]

you could do with getting this diagnosed as raj may have the parts for sale whats required for you to fix this, and im sure they will be cheaper than the stealers!

[Horizon]

Thanks X5 SPORT
looking into the information you have supplied, the idea I had about the valveblock  passing has been blown out of the water. The car wakes op out of sleep mode several times a night and will re adjust the suspension to deflate the bags to the correct ride height, this is inase through an increase in temp the air expands in the system so raising the ride height, and putting the babs under strain. ( the system will not start the compressor and raise the car, as this would cause battery to drain if the system was leaking. looks to be an electrical / electronic fault.  Too flaming complicated

[james8whippy]

For people stumbling across this post in the future I went ahead and changed the FSR 3 weeks ago and so far the problem is resolved!!  So happy

It's so strange that a FSR can not only cause battery draining issues but also it can mess up the suspension! 

But that's BMW electrics I guess!

[fenderbom]

What is the FSR that you replaced?

I may have the same problem?

[Raj]

[quote="fenderbom"]
What is the FSR that you replaced?

I may have the same problem?
[/quote]

Final Stage Resistor (or hedgehog as it is commonly known). Known issue and can cause a whole host of issues.