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Air Suspension question

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Old 05-25-2014, 12:29 AM   #1
mcs
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Default Air Suspension question

Hi all,

I have a 2004 4.2 Sport with Sports air.

I believe it has been lowered with coding by the previous owner, going from some forum questions,

Today, I noticed the car took a while to get in lift mode. Then when I got home, I noticed that the left side of the car would drop around 10mm and pump up then drop and pump up all the time.

In Comfort/auto/dynamic the ride height is constant. The compressor isn't noisy, and there are no warning lights.

Very occasionally, the same side of the car that has issues, the headlight will stay pointed down. Could the level sensor be sending crap messages?

I have a scan cable coming but I am sure the suspension stayed constant in lift mode.

Thing is, it isn't a leak, the suspension hissing is controlled by the car. Thoughts?

Mike
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Old 05-25-2014, 11:00 AM   #2
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scanning is certainly a good means of sorting out the real problem. As for the 1 corner you mention there may be a pinch/hole that is only exposed at a certain height, had similar issues with allroad airsprings, and there is really not much difference between allroad springs and the A8's springs. Get you VCDS cable and go from there is my advise though.
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Old 05-25-2014, 12:36 PM   #3
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Quote:
Originally Posted by 03_AR_CO View Post
scanning is certainly a good means of sorting out the real problem. As for the 1 corner you mention there may be a pinch/hole that is only exposed at a certain height, had similar issues with allroad airsprings, and there is really not much difference between allroad springs and the A8's springs. Get you VCDS cable and go from there is my advise though.
Concur. You need to get to the bottom of this quickly, otherwise you'll be buying more than just a new/ reman air spring/ strut assembly (i.e. new compressor, after all that duty cycling burns yours out).
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Old 06-04-2014, 02:18 AM   #4
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I have done a scan of the car,

It says the G291 valve thing is faulty.

Is it expensive to replace and it should solve the problems? The compressor isn't noisy and the car struts don't seem to leek. The compressor is only really 30k miles old. Same with the relay.

Mike

2 Faults Found:
01487 - System Function Test
008 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 120
Mileage: 175045 km
Time Indication: 0
Date: 2014.05.17
Time: 09:27:55

01772 - Signal from Level Control Pressure Sensor (G291)
008 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 3
Fault Frequency: 11
Reset counter: 146
Mileage: 175399 km
Time Indication: 0
Date: 2014.05.22
Time: 17:25:37
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Last edited by mcs; 06-04-2014 at 02:55 AM.
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Old 06-04-2014, 09:45 AM   #5
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Default The more you know, the more things to worry about...

I have no idea how to tackle these problems even if they exist in my scan. BTW, which module do you scan to get this? Autoscan?

Cheers,

Louis
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Old 06-04-2014, 10:25 AM   #6
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Pressure sensor is integrated into the valve block so not replaceable without changing the valve block. All that kit is located behind the front left wheel arch liner. First thing to try is cleaning up the electrical connectors on it as they may be the cause. If that doesn't work then a new valve block is needed. $250 plus fitting. Competent DIYer job. Just make sure you have car on axle stands/lift otherwise it will hit the deck when you disconnect the airlines and you'll struggle to get a jack back under it.
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Old 06-04-2014, 11:33 AM   #7
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Quote:
Originally Posted by mcs View Post
I have done a scan of the car,

It says the G291 valve thing is faulty.

Is it expensive to replace and it should solve the problems? The compressor isn't noisy and the car struts don't seem to leek. The compressor is only really 30k miles old. Same with the relay.

Mike

2 Faults Found:
01487 - System Function Test
008 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 120
Mileage: 175045 km
Time Indication: 0
Date: 2014.05.17
Time: 09:27:55

01772 - Signal from Level Control Pressure Sensor (G291)
008 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 3
Fault Frequency: 11
Reset counter: 146
Mileage: 175399 km
Time Indication: 0
Date: 2014.05.22
Time: 17:25:37
Here is my scan from address 34 before replacing the air compressor, not the valve body:

Address 34: Level Control Labels: 4E0-910-553.lbl
Part No SW: 4E0 910 553 H HW: 4E0 907 553 F
Component: LUFTFDR.-CDC H06 4480
Coding: 0015510
Shop #: WSC 20213 444 84343
VCID: 28541CFE9BAED75EFC3-807D

1 Fault Found:
01772 - Signal from Level Control Pressure Sensor (G291)
008 - Implausible Signal - Intermittent
Freeze Frame:
Fault Status: 00101000
Fault Priority: 3
Fault Frequency: 1
Reset counter: 217
Mileage: 86342 km
Time Indication: 0
Date: 2013.12.22
Time: 10:29:03


My experience with the G291 code is representative of pump in a weakened state.
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Old 06-04-2014, 04:43 PM   #8
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The car wont lift at all anymore. But still no suspension light. It doesn't seem to be excessively low, but I noticed the compressor was on while the car was stopped. I haven't noticed that before.

Does the compressor wear out? Or do they always die as a result of the leak. The car has done just over 100k miles now. but the compressor was replaced in 2011.

I don't think the car has leaking struts as the car holds its level fine it just couldn't get to lift mode.

Mike
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Old 06-04-2014, 06:40 PM   #9
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All the research I am doing seems to indicate a faulty compressor. Since it is making a noticeable noise (though not a deathly noise) I am going to rebuild it with a new piston ring and seal and see how I go.

If this cures it, then I win, as it costs like $30 AUD. A new compressor here is around $2k so I am happy to simply give it a go.

Mike
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Old 06-04-2014, 07:10 PM   #10
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Please take pictures and shoot a video if you can please, it will be a great help.

Cheers,

Louis
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Old 06-05-2014, 10:59 AM   #11
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Quote:
Originally Posted by mcs View Post
The car wont lift at all anymore. But still no suspension light. It doesn't seem to be excessively low, but I noticed the compressor was on while the car was stopped. I haven't noticed that before.

Does the compressor wear out? Or do they always die as a result of the leak. The car has done just over 100k miles now. but the compressor was replaced in 2011.

I don't think the car has leaking struts as the car holds its level fine it just couldn't get to lift mode.

Mike
Of course they wear out- nothing that's mechanical in nature lasts forever. The more the thing runs, the faster it'll wear out- just like anything else. If you want to make sure it runs a lot, spring a leak in the system somewhere, and ignore it. Then it'll wear out in short order.

Yes, the compressors can be overhauled.

It sounds like you have a failed/ failing pump, and possibly a bad valve block. Likely not a leaking strut, since as you say, the car will sit level over time.
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Old 06-05-2014, 05:24 PM   #12
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Park the car up with jacking mode (disables auto leveling) enabled over night. That will tell you if you have a leak or not and where it is based on which corner or end sinks.
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Old 06-05-2014, 05:38 PM   #13
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Quote:
Originally Posted by dvs_dave View Post
Park the car up with jacking mode (disables auto leveling) enabled over night. That will tell you if you have a leak or not and where it is based on which corner or end sinks.
Yeah I have done that, and the car stayed level. It levels fine in Comfort and Auto and Dynamic, it takes forever to get into lift.

The ride is harsher than it used to be, The car has Sports Air so all the heights except lift are the same.

I think its just a worn compressor. I will simply replace the piston ring, and a seal and see how that goes.

If it goes well, for $30 the rebuild kit costs, I would probably redo it every 1-2 years as a preventative.

Mike
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Old 06-05-2014, 06:56 PM   #14
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I just installed the rebuild kit on a friends car took about 2 hours. It's fairly simple once you get the wheel liner off. 3 10mm bolts hold it on the car. Once it is off follow these Instructions
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Old 06-06-2014, 04:06 AM   #15
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Or disassemble the motor and epoxy/ JB Weld the loose magnet back in place. Then add glue to the magnet that has not yet failed.
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Old 06-06-2014, 08:05 AM   #16
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If the compressor has "melted down" meaning it has kept running until the motor burns out it is not worth rebuilding. A new compressor is about $500. If the compressor is "weak" it may be worth rebuilding.
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Old 06-06-2014, 01:52 PM   #17
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Link to the original, well-engineered rebuild kit: BagpipingAndy

Quote:
Originally Posted by dvs_dave View Post
Pressure sensor is integrated into the valve block so not replaceable without changing the valve block. All that kit is located behind the front left wheel arch liner. First thing to try is cleaning up the electrical connectors on it as they may be the cause. If that doesn't work then a new valve block is needed. $250 plus fitting. Competent DIYer job. Just make sure you have car on axle stands/lift otherwise it will hit the deck when you disconnect the airlines and you'll struggle to get a jack back under it.
And may I add that the lines have tiny, fragile ferrules which, if I had to do a valve block R&R, I'd be sure to have spares... or at least be ready to note how they fit and catch any which fall out of the nut when you d/c the air lines (the ferrules start as one piece but have a segmented construction which is prone to break if flexed at all. They still work in two pieces, but you might want some kind of magnifying safety glasses cause they're awfully small and fiddly...)

Quote:
Originally Posted by Mister Bally View Post
Or disassemble the motor and epoxy/ JB Weld the loose magnet back in place. Then add glue to the magnet that has not yet failed.
Doesn't this failure mode create a certain rattling/clacking sound? Has he mentioned that (forgive me if so).

Re the G290 temp sensor and its reporting "implausible" (love that one) signals and over-temp shut offs, you can disconnect it and the module won't even set a DTC! Well how does it function, you ask? There's a built-in algorithm to cycle the pump based on ambient temp, run time, and moon phase. On mine, the wire (attached to the car, naturally) was broken inside the connector strain relief (connector being on the wire 6" or so from the pump). You should check that wire and connector carefully. The unbelievable thing is the wire was about 22ga (like earbud-wire size) and, about four-conductor! The copper was almost brittle! It appears thick because of its insulation.

Link to my adventure, FWIW, and compressor autopsy so you can see what's inside...
and a discount code from Arnott, not sure if it's valid anymore.

Re hissing, there's supposed to be a filter (located at the top of the wheel well after you get the liner off) on the clear in/out line to the compressor; on mine it had detached, and the thing sounded like it had air brakes. Pretty sure it's pictured in my big post; if not it's just like a mower fuel filter about 5X5cm (so relatively large); in fact I googled the # on it and it was a small engine fuel filter. Pretty sure it was original to the car, though.

Lastly, I think you said replaced it already, but new (stupidly located) compressor relay must accompany new compressor, and while you're in there do the $20 brake light switch - save many hard-to-diagnose headaches later on (and they fail a lot). Be aware the switch's plunger self-adjusts and you must not depress the plunger before you install it (and then the brake pedal arm will press it in and set it) because it cannot be undone. (ask me how I know).

-Tom
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Old 06-06-2014, 02:53 PM   #18
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Quote:
Originally Posted by aTOMic* View Post
Link to the original, well-engineered rebuild kit: BagpipingAndy



Doesn't this failure mode create a certain rattling/clacking sound? Has he mentioned that (forgive me if so).
Sometimes just a slower motor RPM and low air output as the armature is dragging on the loose magnet.

Sometimes an unusual noise.
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Old 06-19-2014, 03:21 AM   #19
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Some developments;

I found the car's coding was 0011310 instead of the 0015510. This meant the car was 20mm lower than the normal sports height at the front and 10mm lower at the rear. (or 40 and 30mm lower than the normal non sports air ride heights)

I have changed it back to 0015510 as the ride was terrible and I don't much care for looks over my own comfort. (If it is too high I will lower it to 0013310 later)

However it seems that the front left strut makes a hissing noise independent of the valve air release thing. The code also added an air leak code to the G291 sensor code.

I suspect I need a new front left strut. The right one was replaced some time ago, I believe the left one is original.

Mike
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Old 06-22-2014, 02:08 PM   #20
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What brand and where do you guys get struts from?

Arnott don't seem to post internationally, and I am sure the dealer here would want about a hundred and twenty-twelve million for one.

My car has the sports air also, so are the struts different or is it all in the ECU? (I know the part numbers for the struts are different but are they actually changed?)

Also, is there any worth to the remanufactured ones?

Cheers guys.

Mike
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Old 06-22-2014, 02:08 PM
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