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  #13  
Old 01-25-2011, 01:13 PM
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Re: Is this noise normal?

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Originally Posted by rdalcanto View Post
Right, but is the compressor running when the shocks are changing height, or at other times to build pressure in the tank?

My understanding is that the compressor is only running to shift the pre-pressurized nitrogen back and forth between the holding tank and the shocks.

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Old 01-25-2011, 01:32 PM
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Re: Is this noise normal?

I am totally sure it is compressing the nitrogen even more than when it is put in. You wouldn't need a compressor to move compressed air around, just a computer controlled valve block.
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  #15  
Old 01-25-2011, 01:46 PM
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Re: Is this noise normal?

Here's a link to everything you ever wanted to know about the Wk2 QL.

http://www.wk2jeeps.com/wk2_quadralift.htm
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  #16  
Old 01-25-2011, 02:11 PM
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Re: Is this noise normal?

The key to remember here is that although it's a closed system the nitrogen which is stored in the tank is at a lower pressure than the air springs. Otherwise, it would never be able to vent the nitrogen back from the springs into the tank. The compressor is used to feed the air springs using nitrogen that's slightly pressurized in the tank.

Below is from wk2jeeps.com, it explains why and when the compressor runs. In the case here I suspect the occasional sound could be from the system making minor adjustments vs. the example below which is an entire ride height change.

Here's an example of how the system functions when lifting from Normal ride height to Off-Road 2:
The vehicle starts at Normal (NRH).
The driver requests the OR2 position by pressing the “Up” button on the air suspension switch twice.

The EVIC displays and the LED status changes on the air suspension switch.

Using height sensors, the system determines the vehicle needs to be raised in order to achieve the proper height at the four suspension corners.

It actuates the compressor and valve block, moving air from the reservoir to the rear axle air springs.

Using the rear axle height sensors, the system determines when the rear axle is at the correct intermediate height and keeps the compressor running but switches the valve block so that air flows from the reservoir to the front axle air springs.

Using the front axle height sensors, the system determines the front axle is at the correct intermediate height.

The LED status changes.

The system keeps compressor running but switches the valve block back again, moving air from the reservoir to the rear axle air springs.

Using the rear axle height sensors, the system determines when the rear axle is at the correct final height and keeps the compressor running but switches the valve block so that air flows from the reservoir to the front axle air springs.

Using the front axle height sensors, the system determines the front axle is at the correct final height and leveling is complete.
The LED status changes and the EVIC message “Off Road ride height Level 2” is displayed.
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Old 01-25-2011, 02:14 PM
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Re: Is this noise normal?

It still doesn't give very detailed information each of the functions. Hopefully the site will update to add more info when it is available.

Like:
http://rangerovers.net/repairdetails...ion/index.html
http://rangerovers.net/repairdetails...nsion/ecu.html

"A compressor (housed in a sealed circular enclosure inside the spare wheel compartment under the rear loadspace) keeps system pressure between 9 and 13.7 bar (135 and 200 psi). . The compressor eventually wears out resulting in slow pumping -- if bad enough will cause fault mode when takes too long to reach pressure. The compressor incorporates a temperature sensor that is read by the ECU, which shuts off the compressor if it overheats. Failure of this sensor can cause the compressor to stop pumping. In the Mk III the electric driving the compressor can easily be replaced as a deparate part. There are many conditions that inhibit operation fo the compressor; however failure of the motor to operate at all may mean a blown fuse or relay."
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Old 01-25-2011, 02:27 PM
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Re: Is this noise normal?

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Originally Posted by mjw930 View Post
In the case here I suspect the occasional sound could be from the system making minor adjustments vs. the example below which is an entire ride height change.
I don't think it is the compressor for the QL, because when I'm parked, and making it go up and down, I can't even hear the compressor. So why would I hear it while driving? After I post the video, everyone needs to drive with the radio off and see if they have it too....
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  #19  
Old 01-25-2011, 02:44 PM
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Re: Is this noise normal?

Quote:
Originally Posted by GC2011 View Post
It still doesn't give very detailed information on the functions. Hopefully the site will update to add more info when it is available.

Like:
http://rangerovers.net/repairdetails...ion/index.html
http://rangerovers.net/repairdetails...nsion/ecu.html

"A compressor (housed in a sealed circular enclosure inside the spare wheel compartment under the rear loadspace) keeps system pressure between 9 and 13.7 bar (135 and 200 psi). . The compressor eventually wears out resulting in slow pumping -- if bad enough will cause fault mode when takes too long to reach pressure. The compressor incorporates a temperature sensor that is read by the ECU, which shuts off the compressor if it overheats. Failure of this sensor can cause the compressor to stop pumping. In the Mk III the electric driving the compressor can easily be replaced as a deparate part. There are many conditions that inhibit operation fo the compressor; however failure of the motor to operate at all may mean a blown fuse or relay."
The biggest difference between the older generation open systems like the RR and VW/Porsche/Audi and the newer generation closed systems is how they use the storage tank. On the older systems the valves connect to the tank and the compressor connects to the tank. Every time you lower the system it vent's each shock to air and the compressor needs to "replenish" that air in the tank. With the closed system nitrogen is moved between the tank and the shocks which reduces the pump size needed as well as how hard it has to work. The nitrogen is pressurized in the tank, probably at a level close to the pressure in the springs at normal ride height. That way the compressor only has the move the difference between normal and the other settings, not the entire amount as it would if it was filling a tank after the shock vented to air. It does mean it runs in both directions, up and down but since it such a small pressure difference the length of time and the wear and tear should be greatly reduced.

Check out this site, it's a good primmer on air suspensions.:

http://www.vehicledynamics-expo.com/...rotendorst.pdf
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  #20  
Old 01-25-2011, 02:45 PM
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Re: Is this noise normal?

Does it sound like this:

?
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Old 01-25-2011, 02:45 PM
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Re: Is this noise normal?

Quote:
Originally Posted by rdalcanto View Post
I don't think it is the compressor for the QL, because when I'm parked, and making it go up and down, I can't even hear the compressor. So why would I hear it while driving? After I post the video, everyone needs to drive with the radio off and see if they have it too....
There you go, then I wasted the entire preceding post Looking forward to the vid.
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  #22  
Old 01-25-2011, 02:48 PM
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Re: Is this noise normal?

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Originally Posted by JoeSchmoe007 View Post
Does it sound like this:

?

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Old 01-25-2011, 04:10 PM
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Re: Is this noise normal?

Here is the video. You have to turn your volume up to hear it. You probably can't hear the faint set very well, but you should be able to hear the louder second set (16-19 seconds on the time). On the drive home, it didn't do it once, so it is pretty rare. Just want to know what that is....


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  #24  
Old 01-25-2011, 04:22 PM
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Re: Is this noise normal?

I've definitely never heard that one.
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