Member Since: 17 Mar 2008
Location: NSW
Posts: 706
The air suspension ecu is powered all the time including the sensors. It checks the level after 2 hrs then every 6 hours thereafter and will progressively lower corners to match the lowest one.
23rd Feb 2010 11:46 am
evo8
Member Since: 29 Jan 2008
Location: Zalesie
Posts: 289
thanks - did not know that that means that problem can be at front left as it is the one that starts to lower first...2013 D4 TDV6 S; Baltic Blue; IID Tool BT
2007 D3 TDV6 SE, Auto; club Faultmate MSV2
It's sounds similar to mine. A good way to test is to startup the car, let the suspension rise to access hight and disconnect the main battery over night. If it still drops, it's a leak, if not, probably electronics.
Mine started like yours, dropped over 3 days, then became one and within a month you could see the car drop as you switch off.
It was always the front right, and the rest will follow (auto leveling) during over night. Sometimes the front left will drop immediately with the right.
It sounds like a valve block to me, but Baben and other guys might have other ideas to isolate and diagnose the fault.2007 TDV6 SE auto (ex Write off)
2013 D4 SDV6 SE auto
Sorry not access hight, but normal or off road hight.
If your car runs normally when started, it's not a hight sensor.2007 TDV6 SE auto (ex Write off)
2013 D4 SDV6 SE auto
23rd Feb 2010 12:48 pm
Baben
Member Since: 15 Feb 2006
Location: Kyalami
Posts: 2059
with the faultmate, you can see the voltages and heights of all the sensors as well as the pressure in the gallery, and the position of all the valves. Armed with this information you can make a diagnosis.
For instance, we managed to establish that one chap's gallery pressure was dropping 200kpa over 10-15 minutes, so the investigation started at the compressor side ofthe system rather than looking for faults on each corner of the vehicle.
its not easy, and this system is quite complex, but the dealers seem to be worse off than we are
I agree with Jacques' opinion in your case, seeing as the symptoms are similar to his issue. If the whole system drops simultaneously then logic would dictate that there is a central issue. If your one corner drops first, that would logically be the place to start investigating. Whether this logic applies to this Disco system, I can't tell
24th Feb 2010 7:39 am
evo8
Member Since: 29 Jan 2008
Location: Zalesie
Posts: 289
thanks for the info - I have a log from the suspension inputs - after compressor fills in to cca 1780Kpa (and switches off) then the gallery pressure starts sinking (all valves are shown as closed in the log). The pressure sinking is at rate cca 120kPa per minute. On other two D3 that I did the same test (not sinking symptoms) - the pressure is decreasing at a rate 40kPa per minute. Even this decrease is huge - but these cars are not sinking. What the hell does it mean ?!?!
if all valves are closed - which part of the system actually the gallery pressure relates to? has anyone got the diagram for the system ? thanks2013 D4 TDV6 S; Baltic Blue; IID Tool BT
2007 D3 TDV6 SE, Auto; club Faultmate MSV2
LR showed the same results (vaslves closed), that is why they started with airsprings (the pressure is being lost) some where and the valves shows closed.
this was the same reason why LR only looked at the valve block as a last result, everthing was new and it was still dropping pressure2007 TDV6 SE auto (ex Write off)
2013 D4 SDV6 SE auto
24th Feb 2010 10:59 am
Baben
Member Since: 15 Feb 2006
Location: Kyalami
Posts: 2059
IMO It is not logical to replace airsprings if the gallery pressure reduces constantly, because even if one or more airsprings have leaks, the gallery pressure would not reduce constantly (especially if the vehicle is switched off and battery disconnected) unless there is a leak in one or more of the valves. Hence the valves are the place to start, and which one is the question.
If you can get a functional diagram of the system you will be able to solve the mystery even easier.
Its quite logical though, based on the experience of other forum members, we have the following info:
If the gallery pressure is decreasing and the vehicle is not sinking, then you know the pressure is being lost in the compressor area before the corner valves, and probably before the cross link valves. This was a common issue and I think it was a recall on '06 vehicles where they replaced the compressor and reservoir valve. I have also heard of the reservoir leaking thru the bung. This is relatively easy to check because its all very accessible.
You have (AFAIK) 4 corner valves, 2 cross-link valves, a reservoir valve (which is where you are losing the pressure if the gallery pressure reduces but the car doesn't sink) and an exhaust valve (the one that makes the farty noise at least on my car)
If the car is sinking on one corner first, then the culprit is usually one of the corner valves, or a leak in either the pipe or the airbag. (Has anyone actually had a leaky airbag?)
You do need to monitor the vehicle though, cos it will eventually decrease pressure in the other corners to try maintain level.
Has anyone had a leaky cross-link valve, and what would the symptoms be?
25th Feb 2010 6:52 am
evo8
Member Since: 29 Jan 2008
Location: Zalesie
Posts: 289
thanks - the compressor assy seems to be a good starting point as based on the diagram I ve been able to get the gallery pressure sensor is right at the assembly.
Click image to enlarge
from log it is apparent that before the engine is started the gallery pressure is 150kPa - right after start - the reservoir valve open and the pressure goes up to 1700Kpa (means that reservoir keeps the pressure) - then goes down as the corner valves open to raise the vehicle. The of course the compressor start to run and fills the missing pressure - but runs for cca 2 minutes.
Last edited by evo8 on 25th Feb 2010 10:59 am. Edited 1 time in total
25th Feb 2010 10:24 am
frogall
Member Since: 29 Aug 2008
Location: Norfolk
Posts: 250
I have a leaking air strut - diagnosed with a water spray by an independent garage
The culprit sinks over about a day - has done this for about 9 months and not got worse.
What does not happen is the car settling to compensate at any other corner.
Starting and running is fine - it sets itself up and works properly.I'm on a whisky diet. I've lost three days already.
25th Feb 2010 10:49 am
evo8
Member Since: 29 Jan 2008
Location: Zalesie
Posts: 289
GraemeS wrote:
The air suspension ecu is powered all the time including the sensors. It checks the level after 2 hrs then every 6 hours thereafter and will progressively lower corners to match the lowest one.
Are you sure about this - the local lr service technician told me that no - the car is asleep and does nothing now i do not know ....2013 D4 TDV6 S; Baltic Blue; IID Tool BT
2007 D3 TDV6 SE, Auto; club Faultmate MSV2
15th Mar 2010 7:14 pm
evo8
Member Since: 29 Jan 2008
Location: Zalesie
Posts: 289
today I was told by service that I should put the car in extended mode; disconnect the battery and observe the sinking overnight and report the result back. this indirectly confirms that with battery connected it probably levels itself in some intervals. 2013 D4 TDV6 S; Baltic Blue; IID Tool BT
2007 D3 TDV6 SE, Auto; club Faultmate MSV2
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thanks - did not know that 
that means that problem can be at front left as it is the one that starts to lower first...
Sorry not access hight, but normal or off road hight. 
now i do not know ....
