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D3 - Axles, Brakes, Suspension and Steering Brakes, Springs, shocks, steering racks, steering columns, suspension arms, wheel hubs etc.

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Old 9th February 2020, 11:53 PM
Versace Versace is offline
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Default Air compressor cycling

How much does you compressor run?

I'm on a brand new unit since I bought the car with a "suspension" failure, it
was flat on the ground…
- front two struts are brand new units (Arnott)
- rear ones are original but O.K. (the car starts to sag in the back after the battery is removed for 6-7 days)
- compressor is a brand new unit and it goes to 16 bar like nothing
- we got some wierd codes and the car did not accept adaptation-calibration so we changed the air suspension computer under the glove box, everything fine now with calibrating and no codes
- all four corners got new leveling sensors
- valve block replaced with a used one just to be sure it Works (donor car from my friend, got rear ended)
- relay replaced for an Original Audi unit

Now, everything Works normal and ok I just want to ask you how much do you hear your relay clicking - turning on the compressor?
I can drive it on a highway for an infinite time without it kicking in, but as soon as I stop and turn the engine off, nex time I start it, it kicks in for only a second or two. Doesn't matter if I turn it off for 5 seconds or three days.
The same goes if i stop, leave it running, I step out of the car - than it readjusts the front, I sit back in and drive away. Right after driving away it starts to run for a second or two.
Is this normal?
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Last edited by Versace; 9th February 2020 at 11:55 PM.
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Old 10th February 2020, 12:26 PM
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homer simpson homer simpson is offline
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I think it is all normal. Are you driving it in automatic or comfort? Mine is in usually in dynamic and it doesn't usually kick in however when I have it in auto, it tends to release air when I park it and then compressor kicks in when started to raise it slightly.
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Old 10th February 2020, 12:33 PM
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steamship steamship is offline
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Regarding the rear sagging after 6-7 days, that would hint at a slow leak. If you haven't already done so, I'd check out all the parts by spraying with soapy water and looking for bubbles.

As to how the air suspension works, check out the following SSP document. It's located in the D3 Tech Dump thread under D3 Common Faults, and is an interesting read. Page 31 may be relevant here to the question you're posing:

56-SSP 292 adaptive air suspension in the Audi A8.pdf
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Old 10th February 2020, 12:47 PM
Versace Versace is offline
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Thanks guys, I’ve read it all allready.
I intend to replace the rear air struts as well. As the schock absorber is working, I think I will be replacing the air bladder unit separately.
90% of the time I drive it in Comfort. If I cruise above 130/140km/h i put it in Automatic as Dynamic is a bit to firm for my taste
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A8 D3 4.2 40V BFM
A8 D2 4.2 40V AUW
Porsche Cayenne S 4.5

Last edited by Versace; 10th February 2020 at 12:50 PM.
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