Pressure valve questions
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From: Rocky mtn High
Pressure valve questions
In an effort to fix my issue. right now the rear rises but the front is fully down. I changed the Valve block with no improvement. But when I disconnected the rear hose from the valve block, the rear came down. Is that a sure sign the rear valves are working??
And conversely if the front valves were bad, would it not air up??
And conversely if the front valves were bad, would it not air up??
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From: Rocky mtn High
well, I just tried to swap the lines, I figured how would it know the difference... But I guess It did. I pulled the F and R lines off, all 4 let out some air. The rear (which was Up) lowered about half way. I then reconnected the lines with the F and R swapped. turned the car on and the pump began to run, but nothing happened, the front didnt budge and the rear didnt go up as it did before. then the pump stopped and got an error 1772 " Implausible signal/Signal lead for pressure sensor"
Is it possible to simply use and air compressor and try and put air into each corner line and see if one front corner raises?
Is it possible to simply use and air compressor and try and put air into each corner line and see if one front corner raises?
Burning Brakes
Joined: Oct 2009
Posts: 860
Likes: 89
From: RI
The valves on the airbag are called pressure holding valves. I forget exactly how they work. You do need a special tool to remove them, fear not, it’s widely available and inexpensive. Perhaps someone can chime in and remind us how they work.
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From: Rocky mtn High
ok well to answer my own question, YES you can put air into each line and it will inflate the air bag. Interestingly, I had my pressure on the compressor around 100psi, so I put air into the Airbag line (front) and I could hear it filling, then it stopped; that corner raise about 2". I thought, did I run out of air?? (30gal tank) I pulled air nozzle off and air came out pretty good, and I still had plenty of air pressure in the Compressor. Surprised that it took that much pressure. (obviously it stopped once the pressure equalized) Also I was able to cap the line with my thumb and hold it. So at least I know the Fronts work. Now just to figure out how to get the system to send air to the front!!!
im going to pull the air valves in rear and see what that does.
im going to pull the air valves in rear and see what that does.
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From: Rocky mtn High
well I pulled cleaned and bathed in oil for 30min the rear air valves. Made 0 improvement. the rear still rises but nothing in the front.
So i was going over the readings again. I see that my system/tank pressure seems to be about 3580mb, which equates to 52psi,(and the air bags at 5580mb (80psi)) But if the rear rises then, thats enough to work No??
and (I couldn't find 100% accurate info) but it says system pressure should be about 10bar which is 145psi (but I have seen a couple mentions of system working at 8 bar (120psi)
can anyone tell me if that would give me THIS error? and can anyone point me to actual pressure readings so i have something to compare to? I couldnt find an actual chart with pressures.
So i was going over the readings again. I see that my system/tank pressure seems to be about 3580mb, which equates to 52psi,(and the air bags at 5580mb (80psi)) But if the rear rises then, thats enough to work No??
and (I couldn't find 100% accurate info) but it says system pressure should be about 10bar which is 145psi (but I have seen a couple mentions of system working at 8 bar (120psi)
can anyone tell me if that would give me THIS error? and can anyone point me to actual pressure readings so i have something to compare to? I couldnt find an actual chart with pressures.
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From: Rocky mtn High
Dang it again! I rebuilt the pump, it seems to work better... Now im not getting any errors... but the front STILL doenst go up!! WTF!!!
one thing that seems interesting is that when I try to put it in Loading position, it always says "pressure accumulator filling"
so with no errors where else do I look?
one thing that seems interesting is that when I try to put it in Loading position, it always says "pressure accumulator filling"
so with no errors where else do I look?
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Burning Brakes
Joined: Oct 2009
Posts: 860
Likes: 89
From: RI
Can you give us an update on which parts have been replaced at this point?
Try mechanically disconnecting the ride height sensors at the front, then hook up your scan tool and move the sensor’s arm. See if the value for ride height changes on the scan tool as you manipulate the sensor.
While I can’t say for sure, I don’t think you have a pump problem. You mentioned, the accumulator pressure. There are two accumulators, One for the front and one for the rear. One accumulator is on the left side of the spare tire in the trunk. The other accumulator is underneath the car on the left side approximately underneath the left rear passenger’s feet.
Based on everything you’ve been working on it seems like the front half of the system isn’t getting air pressure and that the electrical system is working. If I had to guess, that means either a leak on the front half of the system. Or the sensors are giving a false reading that won’t trigger the valve block to fill the front. And I think you said you replaced the valve block?
Try mechanically disconnecting the ride height sensors at the front, then hook up your scan tool and move the sensor’s arm. See if the value for ride height changes on the scan tool as you manipulate the sensor.
While I can’t say for sure, I don’t think you have a pump problem. You mentioned, the accumulator pressure. There are two accumulators, One for the front and one for the rear. One accumulator is on the left side of the spare tire in the trunk. The other accumulator is underneath the car on the left side approximately underneath the left rear passenger’s feet.
Based on everything you’ve been working on it seems like the front half of the system isn’t getting air pressure and that the electrical system is working. If I had to guess, that means either a leak on the front half of the system. Or the sensors are giving a false reading that won’t trigger the valve block to fill the front. And I think you said you replaced the valve block?
Last edited by JAGMAN1; Apr 4, 2024 at 08:52 AM.
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Thread Starter
Rennlist Member
Joined: Aug 2017
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From: Rocky mtn High
Can you give us an update on which parts have been replaced at this point?
Try mechanically disconnecting the ride height sensors at the front, then hook up your scan tool and move the sensor’s arm. See if the value for ride height changes on the scan tool as you manipulate the sensor.
While I can’t say for sure, I don’t think you have a pump problem. You mentioned, the accumulator pressure. There are two accumulators, One for the front and one for the rear. One accumulator is on the left side of the spare tire in the trunk. The other accumulator is underneath the car on the left side approximately underneath the left rear passenger’s feet.
Based on everything you’ve been working on it seems like the front half of the system isn’t getting air pressure and that the electrical system is working. If I had to guess, that means either a leak on the front half of the system. Or the sensors are giving a false reading that won’t trigger the valve block to fill the front. And I think you said you replaced the valve block?
Try mechanically disconnecting the ride height sensors at the front, then hook up your scan tool and move the sensor’s arm. See if the value for ride height changes on the scan tool as you manipulate the sensor.
While I can’t say for sure, I don’t think you have a pump problem. You mentioned, the accumulator pressure. There are two accumulators, One for the front and one for the rear. One accumulator is on the left side of the spare tire in the trunk. The other accumulator is underneath the car on the left side approximately underneath the left rear passenger’s feet.
Based on everything you’ve been working on it seems like the front half of the system isn’t getting air pressure and that the electrical system is working. If I had to guess, that means either a leak on the front half of the system. Or the sensors are giving a false reading that won’t trigger the valve block to fill the front. And I think you said you replaced the valve block?
Last night I put in a new level sensor on the Front Right (this one had the lowest reading/measurement, so I figured id try that first)..... But again no difference. it shows pretty much the same reading as the old sensor) Both sensors show the front is down, and looks to be reading relatively correctly (though one side shows about 10mm lower than the other)
I didnt know about the front, from the looks of the diagram its under the drivers seat. and is slightly bigger. I used soapy water at the pump, didn't find any leaks. are there any valves near the front accumulator?
I will say I did get an Initial error when I first start the car, and that is the "below lower limit" but once that is cleared and it runs for a couple minutes, I dont get any more errors. (except for a time out on the pump running) but since the lines were all disconnected previously, that seems reasonable.
Burning Brakes
Joined: Oct 2009
Posts: 860
Likes: 89
From: RI
What is component #8?
Have you leak checked the front half of the system? Check for leaks from rear accumulator #6 all the way around to the pump #3. Not only would I check for leaks, but also the presence of air on the front half of the system. (You won’t have a leak if there is no air pressure).
I know this has been frustrating. Keep at it, at this point it is a point of pride!
Have you leak checked the front half of the system? Check for leaks from rear accumulator #6 all the way around to the pump #3. Not only would I check for leaks, but also the presence of air on the front half of the system. (You won’t have a leak if there is no air pressure).
I know this has been frustrating. Keep at it, at this point it is a point of pride!
Three Wheelin'
Joined: Mar 2011
Posts: 1,907
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From: Roy, WA
I do have the pdf Level Control manual, it is only 1.8Mb if you want a copy. The diagram is on Pgs 2-3.
No. Description of component Number Location
-1- Air spring strut, front axle 2 Wheel housing/lower control arm
-2- Air-spring strut, rear axle 2 Damper housing (cross
member)/wheel bearing housing
-3- Compressor 1 Underbody right
-4- Valve block 1 Underbody right
-5- Front accumulator, 5.21 litres 1 Underbody left
-6- Rear accumulator 4.87 litres 1 Boot floor plate
-7- Air suspension control unit 1 Luggage compartment right
CALIBRATION
Calibration must be carried out if control unit and/or self-levelling sensors are replaced. When doing this, the
self-levelling sensors are calibrated by determining a correction value (corresponding to the actual height of
vehicle) and permanently storing it in the control unit.
Notes on calibration
The nominal values for the nominal heights of the level sensors are stored in the control unit. The actual values
of the respective axle heights, front left, front right, rear left, rear right, have to be measured manually and then
entered with the Porsche System Tester. The actual values are to be measured on the two axle supports (front
axle, rear axle), both on the right and left. --> Conditions for carrying out calibration.
Measuring point for rear axle
-8- Body acceleration sensors ( 2x front
and 1x rear)
3 Front wheel housing (right/left),
boot floor plate right
-9- Wheel acceleration sensors 2 Spring strut front
-10- Self-levelling sensors, front axle 2 Control arm upper
-11- Self-levelling sensors, rear axle 2 Control arm upper
-12- Compressed air connection 1 Under seat frame front right
-13- Suction line for compressor 1 Connection to air cleaner housing
No. Description of component Number Location
-1- Air spring strut, front axle 2 Wheel housing/lower control arm
-2- Air-spring strut, rear axle 2 Damper housing (cross
member)/wheel bearing housing
-3- Compressor 1 Underbody right
-4- Valve block 1 Underbody right
-5- Front accumulator, 5.21 litres 1 Underbody left
-6- Rear accumulator 4.87 litres 1 Boot floor plate
-7- Air suspension control unit 1 Luggage compartment right
CALIBRATION
Calibration must be carried out if control unit and/or self-levelling sensors are replaced. When doing this, the
self-levelling sensors are calibrated by determining a correction value (corresponding to the actual height of
vehicle) and permanently storing it in the control unit.
Notes on calibration
The nominal values for the nominal heights of the level sensors are stored in the control unit. The actual values
of the respective axle heights, front left, front right, rear left, rear right, have to be measured manually and then
entered with the Porsche System Tester. The actual values are to be measured on the two axle supports (front
axle, rear axle), both on the right and left. --> Conditions for carrying out calibration.
Measuring point for rear axle
-8- Body acceleration sensors ( 2x front
and 1x rear)
3 Front wheel housing (right/left),
boot floor plate right
-9- Wheel acceleration sensors 2 Spring strut front
-10- Self-levelling sensors, front axle 2 Control arm upper
-11- Self-levelling sensors, rear axle 2 Control arm upper
-12- Compressed air connection 1 Under seat frame front right
-13- Suction line for compressor 1 Connection to air cleaner housing
Last edited by hahnmgh63; Apr 5, 2024 at 05:03 PM.
Thread Starter
Rennlist Member
Joined: Aug 2017
Posts: 801
Likes: 80
From: Rocky mtn High
I do have the pdf Level Control manual, it is only 1.8Mb if you want a copy. The diagram is on Pgs 2-3.
No. Description of component Number Location
-1- Air spring strut, front axle 2 Wheel housing/lower control arm
-2- Air-spring strut, rear axle 2 Damper housing (cross
member)/wheel bearing housing
-3- Compressor 1 Underbody right
-4- Valve block 1 Underbody right
-5- Front accumulator, 5.21 litres 1 Underbody left
-6- Rear accumulator 4.87 litres 1 Boot floor plate
-7- Air suspension control unit 1 Luggage compartment right
CALIBRATION
Calibration must be carried out if control unit and/or self-levelling sensors are replaced. When doing this, the
self-levelling sensors are calibrated by determining a correction value (corresponding to the actual height of
vehicle) and permanently storing it in the control unit.
Notes on calibration
The nominal values for the nominal heights of the level sensors are stored in the control unit. The actual values
of the respective axle heights, front left, front right, rear left, rear right, have to be measured manually and then
entered with the Porsche System Tester. The actual values are to be measured on the two axle supports (front
axle, rear axle), both on the right and left. --> Conditions for carrying out calibration.
Measuring point for rear axle
-8- Body acceleration sensors ( 2x front
and 1x rear)
3 Front wheel housing (right/left),
boot floor plate right
-9- Wheel acceleration sensors 2 Spring strut front
-10- Self-levelling sensors, front axle 2 Control arm upper
-11- Self-levelling sensors, rear axle 2 Control arm upper
-12- Compressed air connection 1 Under seat frame front right
-13- Suction line for compressor 1 Connection to air cleaner housing
No. Description of component Number Location
-1- Air spring strut, front axle 2 Wheel housing/lower control arm
-2- Air-spring strut, rear axle 2 Damper housing (cross
member)/wheel bearing housing
-3- Compressor 1 Underbody right
-4- Valve block 1 Underbody right
-5- Front accumulator, 5.21 litres 1 Underbody left
-6- Rear accumulator 4.87 litres 1 Boot floor plate
-7- Air suspension control unit 1 Luggage compartment right
CALIBRATION
Calibration must be carried out if control unit and/or self-levelling sensors are replaced. When doing this, the
self-levelling sensors are calibrated by determining a correction value (corresponding to the actual height of
vehicle) and permanently storing it in the control unit.
Notes on calibration
The nominal values for the nominal heights of the level sensors are stored in the control unit. The actual values
of the respective axle heights, front left, front right, rear left, rear right, have to be measured manually and then
entered with the Porsche System Tester. The actual values are to be measured on the two axle supports (front
axle, rear axle), both on the right and left. --> Conditions for carrying out calibration.
Measuring point for rear axle
-8- Body acceleration sensors ( 2x front
and 1x rear)
3 Front wheel housing (right/left),
boot floor plate right
-9- Wheel acceleration sensors 2 Spring strut front
-10- Self-levelling sensors, front axle 2 Control arm upper
-11- Self-levelling sensors, rear axle 2 Control arm upper
-12- Compressed air connection 1 Under seat frame front right
-13- Suction line for compressor 1 Connection to air cleaner housing
sure how can I get that?
its getting to be a pain to have the car running to check the system and test everything.
I see very little info about leaks in other places other than the pump and struts.
Thread Starter
Rennlist Member
Joined: Aug 2017
Posts: 801
Likes: 80
From: Rocky mtn High
also, can anyone tell me where is the pressure for the struts measured? is it at/in the struts or just in the line going to them? because they all seem to be reading the same.
Burning Brakes
Joined: Oct 2009
Posts: 860
Likes: 89
From: RI
I would trace every air line in the whole system. Start at the pump and follow the air lines through the accumulators, through the valve block, and ending in the struts. That should help you understand where the front and rear systems become independent.
Unfortunately that diagram doesn’t have the detail you need to understand the flow of the system. From a simple system design perspective, the pump and accumulators must sit on one side of the valve block, and the struts on the other side of the valve block. Looking at that diagram, I can tell that there is more than one line running between components, and those extra lines aren’t shown on the diagram.
Pump fills accumulators, valve block dispenses air to the struts.
Feel free to PM if you need.
Unfortunately that diagram doesn’t have the detail you need to understand the flow of the system. From a simple system design perspective, the pump and accumulators must sit on one side of the valve block, and the struts on the other side of the valve block. Looking at that diagram, I can tell that there is more than one line running between components, and those extra lines aren’t shown on the diagram.
Pump fills accumulators, valve block dispenses air to the struts.
Feel free to PM if you need.