P38A Air suspension sucks

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F

Fingers13

Member
Posts
10
Location
Bishops Stortford
Sorry for what may be a stupid question but why does my air suspension seem to suck the air from the bags rather than fill them up? I've changed the rear ride height sensors and front bags only so all pipework from the valves are on correctly. I've been using the RSW software to set the system up but couldn't get it off the bump stops. I eventually did manage to get some air in them and the back ones inflated to the highest setting for 1/2 hour before randomly returning to the bump stops with the bags having all the air sucked out, any ideas?
 
If the system can't reach a target height then it will drop to the bump stops.
If the engine is off then it will periodically self level to the lowest corner
 
Fingers13 said:
Sorry for what may be a stupid question but why does my air suspension seem to suck the air from the bags rather than fill them up? I've changed the rear ride height sensors and front bags only so all pipework from the valves are on correctly. I've been using the RSW software to set the system up but couldn't get it off the bump stops. I eventually did manage to get some air in them and the back ones inflated to the highest setting for 1/2 hour before randomly returning to the bump stops with the bags having all the air sucked out, any ideas?
Click to expand...
It can't suck the air out dude!!!
Have you done any work on it recently in that area?
 
Hi Mark, that's what i assumed but they crease up like an empty crisp packet. I did replace all the shocks, that's the nearest i got to the compressor & valves housing. I did use a 2 post car lift to do some work under the car so wonder if that would have done any damage?
 
I would like to say yes but its been up and down like a yo yo for the last two weeks whilst I investigate, I think when i eventually did get air in the system the axles were supported on the ground with the chassis weight being picked up on the lift so there was no pressure on the system.
 
Arr, be careful when lowering the car onto empty air-bags, they can fold and get damaged... Also did you know there is a difference between the front and rear shocks as length. If placed wrong you can blow air bags off their seats!!!
 
Umm, I need to go and check now, but they did inflate and stay inflated whilst i was trying to level it with the software so the system worked, albeit I never got them to level before they went back to the bump stops. I've got a feeling you could be right.

I'll go back out with the software, check the shocks and try again.
 
Fingers13 said:
Umm, I need to go and check now, but they did inflate and stay inflated whilst i was trying to level it with the software so the system worked, albeit I never got them to level before they went back to the bump stops. I've got a feeling you could be right.

I'll go back out with the software, check the shocks and try again.
Click to expand...
What are you doing when you say you are trying to level it with the software? Using RSW software to set heights you just enter the same number for all 4 corners, for example, 110 for standard height. Note that you can only change and save one set of heights before going on to the next.

Personally I think the heights are more or less arbitrary so just set a standard height that seems reasonable to you and then subtract for Access and add for Offroad. The system will not accept numbers too far out of acceptable.
 
Gord Wedman said:
What are you doing when you say you are trying to level it with the software? Using RSW software to set heights you just enter the same number for all 4 corners, for example, 110 for standard height. Note that you can only change and save one set of heights before going on to the next.

Personally I think the heights are more or less arbitrary so just set a standard height that seems reasonable to you and then subtract for Access and add for Offroad. The system will not accept numbers too far out of acceptable.
Click to expand...
You cannot just stick 110 in for standard height on all 4 corners. You also cannot set a height that "seems reasonable to you", go out of range and the ECU will return to default settings.
 
Datatek said:
You cannot just stick 110 in for standard height on all 4 corners. You also cannot set a height that "seems reasonable to you", go out of range and the ECU will return to default settings.
Click to expand...
I did that as a base point, set normal height to 108, i think it was and took it from there, measured the actual heights and adjusted as necessary
 
kermit_rr said:
I did that as a base point, set normal height to 108, i think it was and took it from there, measured the actual heights and adjusted as necessary
Click to expand...
Fair enough if there are no numbers in the ECU and you then adjust to the correct height for each level. Normally there will always be settings in the ECU from which to work.
 
Datatek said:
Fair enough if there are no numbers in the ECU and you then adjust to the correct height for each level. Normally there will always be settings in the ECU from which to work.
Click to expand...
There were numbers but they were way out from eachother. I thought it best to start from scratch, so to speak, rather than try to adjust what was already there. Especially as you can only have 2 digits difference between wheels
 
kermit_rr said:
There were numbers but they were way out from eachother. I thought it best to start from scratch, so to speak, rather than try to adjust what was already there. Especially as you can only have 2 digits difference between wheels
Click to expand...
I work the other way round. Using the heights tab in the RSW software, I adjust each corner to the required height on my measuring stick one level at a time, then read the values, still in the heights tab, write them down on paper and then enter them in the calibration tab and write them to the ECU. Easy and accurate. As there is a plus/minus tolerance of 7mm for each corner, it's also easy to get to within 2 bits across the axle although 5 bits also seems to wok OK.
 
Datatek said:
I work the other way round. Using the heights tab in the RSW software, I adjust each corner to the required height on my measuring stick one level at a time, then read the values, still in the heights tab, write them down on paper and then enter them in the calibration tab and write them to the ECU. Easy and accurate. As there is a plus/minus tolerance of 7mm for each corner, it's also easy to get to within 2 bits across the axle although 5 bits also seems to wok OK.
Click to expand...
Aha! Didn't know about the 7mm tolerance!!
 
Hi all back on line, interesting reading re setting the heights. I cannot get that far unfortunately, if I press the EAS unlock and clear the faults it goes straight back into fault mode when I unplug and reset the comms code as per the instructions so it’s still sitting on the bump stops.

I might try re installing the software but I do get the good idle tab go green.

2 shocks were the wrong way round by the way Mark👍
 
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