Well well well....very interesting

Is the 16bar a pressure you would expect from a new compressor at any time as long is not in operation in that time ???

If yes then I'm f***ed

Started with starting a car and letting it set for 3 minutes
I've got a slight slobe side ways on front of the garage setting off car by 7mm on one site as read in measuring blocks.

Starting pressure on Comfort was 4.56 bar

[IMG]http://i1112.photobucket.com/albums/...3/DSC_1570.jpg[/IMG]

Then lowered it to dynamic and pressure after shutting off the valves was 3.25 bar

[IMG]http://i1112.photobucket.com/albums/...3/DSC_1571.jpg[/IMG]

Then lift and 2.28 bar

[IMG]http://i1112.photobucket.com/albums/...3/DSC_1572.jpg[/IMG]


NOW
From Dynamic (there is that slope issue if it matters) to Lift mode it took 1min 22sec !!!!!!!!!!!!!!!!

From Dynamic to Comfort 38sec.


BUT
On the road everything is quicker than that surely, I never was waiting that long, 38sec, or was I??

Then pressure on Dynamic was 2.28 bar

[IMG]http://i1112.photobucket.com/albums/...3/DSC_1573.jpg[/IMG]

...and comfort just over 3 bar
[IMG]http://i1112.photobucket.com/albums/...3/DSC_1576.jpg[/IMG]


Came across that fault during the check (could be after a recent lowering but I erased all the faults on the end), cleared it, the set to different levels and no error.

[IMG]http://i1112.photobucket.com/albums/...3/DSC_1575.jpg[/IMG]


So...am I in s**t ????
How should I refer to that 16 bar value and values taken 5 minutes ago as above???

Cheers another thing for me to start worrying about, honestly these cars are intensive on the wallet and grey hair production.

I'll run VCDS on mine to see what pressure shes pumping out on Saturday and get back here with the findings.

I'll take some readings from mine at the weekend,

Looking at that last picture.

http://i1112.photobucket.com/albums/...3/DSC_1575.jpg

The fault has occurred 41 times since the 18th of December.

I'll run through the same sequence of tests and see what happens with mine with timings, but I cannot do it till the weekend.

This is exactly what I said to myself when I looked at this post originally :mad:

Please do Del +++

Manny, can you post your live results??

Hmmmm....???????

Post your results please, I am very curious guys.
Have you got any other known issues on your suspension, electronic and mechanic issues???

I timed the raise from Dynamic to full lift this morning for you.

From Dynamic to full Lift took just under 30 seconds, all done smoothly in four stages, back, front, back, front.

Before the repair it took a Looooong time.

Cheers Manny +++
But as always I've got few questions:
30sec, is that till the white arrow up disappears or until car stops lifting??
Was that during the drive or on the driveway before you went to work this morning??

1.22sec feels like a long time in my example but even if car stopped lifting (got to the Lift mode) the arrow stayed white for good 20sec +
This could be with car being on a slight slope and control unit was just trying to get it as level as possible???

Waiting for your pressure update later on ;)

Cheers Manny +++

Just a quick update to what I just find out.

I spoke to best Master Technician I know from Audi and what this fella says about the pressure in that video seems to be a bit of b@l@x and is misleading.

16 bar he says=220PSI
Front tyre with max load=41PSI

That is a 5,5 times higher pressure than in a tyre !!!!!

Have you seen the air hoses on the the compressor side, even he said this would be unreal cos even on a new compressor you would be able to hold the pressure with your finger if you unclip the hose because what he says that there is an operating pressure of around 6bar when no leaks !!!!!

6bar seems to be more real than 16bar, but I couldn't really talk to him for long so I didn't asked all the questions and we didnt managed to check the pressure against any document which would give me something to compare my readings to.

Interesting

Manny's and Delboy's pressure readings should make it more clear, especially Manny's after recent fix.

Cheers boys +++

Those figures around 3 or 4 bar shown on screen seem entirely plausible.
You could do some "ball-park" calculations based on the size of the units and weight of the car as a cross-check. ;)

e.g. 3 bar is 3*10**5 N/m**2 (30 Newtons per square cm)
A 2 tonne car on Earths surface will apply a force of about 5000 N on each corner, which at 3 bar needs about 156 sq cm.
If that was a disc it would be about 7cm radius, or 5.5" diameter. How does that match the lifting struts?

Thats funny, just found this info in SSP292:

but this I understand is pressure value inside the springs, can you measure pressure on each spring??? I switched through all the channels yesterday and there was no group for individual springs

''Each suspension strut features residual pressure retaining valves directly at the air connection.
This ensures that a minimum pressure of approx. 3.5 bar is maintained in the pneumatic
springs. This practically eliminates the risk of damage during storage and assembly to the
greatest possible extent.''


Another interesting thing about the accumulator pressure of 16bars not the compressor pressure:

''Accumulator
The accumulator is situated between the
floor of the boot and the rear silencer on the
left-hand side of the vehicle.
Construction:
The accumulator is made of aluminium.
It has a volume of 5.8l and a max. operating
pressure of 16 bar.
Function:
The objective in designing this system was to
reliably satisfy functional requirements
whilst keeping energy consumption to a minimum
(so that the compressor is on as little
as possible). In order to enable controlled
pressure build-up to be effected solely with
the accumulator, there must be a minimum
difference in pressure of 3 bar between the
accumulator and the pneumatic springs''

>>>>>>
Final control diagnosis
Final control diagnosis checks the function of
the compressor, the solenoid valves and the
struts/shock absorbers.
Diagnosis is executed automatically in three
steps.
1. Test of each individual strut by lowering it
20 mm below its current level for a period
of 30 seconds
2. Charge and empty the accumulator
3. Variation of electrical currents to actuate
the shock absorbers
Final control diagnosis is implemented when
the vehicle is stationary and the ignition is on.
The engine may be running. During final control
diagnosis, the yellow warning lamp in the
dash panel insert flashes.

Have not seen the air pipes on D3 but brake pipes and hoses(any car) do not look too impressive however they can handle 150-200 Bar.

I'll see what I can do this evening, the compressor outputs 16bar and that fills up the pressure resevoir, in turn that supplies the valve block, which feeds all four struts. So the 16 bar is used to maintain all four struts, thats only 4 bar each. The actual air needed will be less otherwise the compressor will be running pretty much all the time. I would expect to see close to 16bar at the G291 sensor, but maybe I'll be proved wrong.

Right I did some testing in the office carpark before driving home.

Starting point, car has been parked all day and compressor has not yet run.
http://forum.a8parts.co.uk/attachmen...7&d=1391193039
Reading
http://forum.a8parts.co.uk/attachmen...8&d=1391193039

Down to Dynamic
http://forum.a8parts.co.uk/attachmen...9&d=1391193039
Reading
http://forum.a8parts.co.uk/attachmen...0&d=1391193039

Up to Lift
http://forum.a8parts.co.uk/attachmen...2&d=1391193039
In Motion, compressor on.
http://forum.a8parts.co.uk/attachmen...1&d=1391193039
Fully Lifted
http://forum.a8parts.co.uk/attachmen...3&d=1391193039

If you view the attached VCDS log which I did driving home from work, you can see that the sensor does ramp up to in excess of 10 bar.

Hi Mannyo,

Pressure in the Accumulator is available to any / all the struts, its not divided by 4.

Each Strut has a solenoid valve dedicated to it that opens in conjunction with the valve that isolates the accumulator.

I went out just now and tested mine, and using measuring bocks in VCDS I could see between 3 - 9 bar depending on if i was going up or down.

I did my first set of tests using the mmi to raise and lower the car with the engine off, the compressor would not run and after 4/5 up down sequences the accumulator emptied and lift was greyed out on the mmi.

Once started the compressor ran and charged back up.

All that said I found there is a better way to test and that's to go to output tests in the level control module and run them, it will go through many tests but the one that we should pay particular attention to is Accumulator test.

Unfortunately I didn't let mine run long enough and it didn't charge high enough to satisfy the test.

I will do another test tomorrow as the compressor was up to around 60 degrees after all my dicking around.

Del,

I have just attached an excel spreadsheet to post 53, which is a log of the suspension activity on my drive home.

:Confused:

Looks like I'm short at least 2bar from your top readings, especially Lift and Comfort (Automatic) ????

Is the log always available and autosaves every time you stop a car or you have to enable test via VCDS before journey ??
Sorry, this might be a stupid question +++

For the log, on the measuring screen press the log button in the bottom right. VCDS will ask for a filename, then off you go. When done, press close log and look in the logs folder.

Cheers Manny +++

...wait, do you guys think that lower pressure could be the reason behind lowering issues, such as each axle won't go below -10 or -15mm mark from the zero value ??

Sorry, completely different subject, but I'd like to see what you think/know about that

Looking at your logs I would say your compressor is good, looking through it I guess you were either changing the settings in mmi or you were running in automatic and went above the speed threshold were the car self lowers.

The way the system works the pressure reading is only true when the car is being lifted when the accumulator valve is open.

With that in mind the best test will be by doing the output tests i mentioned earlier as it is the only way you will get a max pressure reading.

Your log shows that the compressor quickly recovers the pressure when it switches on so your good.

Marcin for your lowering issue I don't think thats pressure related as to have the car lower air needs to be released from the strut not put in.

Max pressure on my Comp
 

Hi Chaps,

As promised heres my pressure (max) reading.

To carry out the following test the engine does not need to be running, which helps as you can hear the compressor start and stop.

To get the true output of your compressor, open Level control module (34) and select output test

http://forum.a8parts.co.uk/attachmen...1&d=1391381662

Then keep clicking next through the tests until you get to Pressure Accumulator test.

Once you have started the test you will hear the compressor run, let it run till it stops and you will see your max pressure.

http://forum.a8parts.co.uk/attachmen...1&d=1391381662

Del, Thanks +++

Interesting, will do test on mine tomorrow ;)

Just to update this, I scanned the car this evening with VCDS which included the level control module. Since having the compressor rebuilt, no faults have been logged at all so its looking good.

Gutted :(
Bought the kit and today took out the compressor.
Followed the instructions and one of the bolts that holds the head on eventually rounded - so unable to get the bolt out :mad:
Even welded a nut on with no joy.

So, put it back - will speak to A8 parts and see if they have any in stock that are known to be good and will have to do a full replacement !!

The only good news is that the grill never sat right, but having put it back together again it now does.......

Hello mate
Can you post a picture just out of interest, more brains = more ways to think of some solution.
I wouldn't replace the compressor if its just the bolt.

Grill sits right, yeah?? At least a little :cheers:

Put everything back now so a bit difficult for the pics.
Will look at the none working keyless entry/start now as will have some spare time over the weekend now+++

Found this using the VAG-CAN cable that M-A8 gave me :)

Do the error codes mean anything to anyone??

http://i15.photobucket.com/albums/a3...ps3c0843c1.png

http://i15.photobucket.com/albums/a3...ps0c1458aa.png

http://i15.photobucket.com/albums/a3...ps68c9a065.png

Cheers

No one can help me :( ??

Yo mate. Sorry, I've been so bloody busy it was unreal. last two weeks 7days a week inc. Good Friday and Monday Bank Holiday.£37k of improvements in 14 days, very stressful.

Did you use Google translator to translate each fault to English, thats what I did in the past. I could get you some info later on about the Gxxx sensor locations if that helps.

Just doing it now to be honest. (the codes are in HEX so changed them to Decimal)
Looks like the usual suspects seen in this thread:
G290 - 01770 (Temperature Sender)
G291 - 01772 (Level control sensor)
N111 - 01397 (Venting Solenoid)

Will need another compressor as I can't get the head off the current one - saw some new ones on Ebay for £300................

(No worries about getting back - thought you may have been busy...)

By the way, when we discussed month or so ago time it takes to raise the from dynamic to comfort. I was moaning about it as after starting the car it was about 30sec mark each time. So I decided to do a output test like Del did, but did't got round it yet. After that I was going to decide about compressor rebuild because of the time it takes to raise suspension.
But, last night, when I got back home I did same test before switching ignition off and on 3 occasions it took only 12sec from Dynamic to Comfort. So it looks like a reservoir tank needs a top up first or valve is not keeping the pressure.

I've got same fault for some time now
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: 30
Reset counter: 114

Would N111 have something to do with the pressure reservoir tank valve. You said one head is rounded, but is the bolt tighten or not fully.
I'm almost 90% sure you don't need to buy a new compressor.
Is it the bolt which holds the compressor or the head??
If its the head one then there must be a way to get that bolt out. Even by welding a T shape bar, 5mm dia, and then undoing it, or something. Shame we can't see it, it would be much easier to came up with some sort of solution.

300 for a compressor seems cheap, I know A8L Chick was replacing her and it was a nightmare to get the right one, they all seem to be same but there are some differences.

Sorry, N111 would be by the compressor

Cheers.

The bolts are tight - I welded on a not to the top and even that snapped off (set my welder to max amps too).
The two bolts hold the head on - once this is off you can then get to the piston ring and replace.

The company reckons that they are from the same company that Audi gets them from! See http://www.ebay.co.uk/itm/compressor...item25795667db

OK, that looks interesting I have to say. New compressor, 330quid, well worth it IF there is no way to undo the bolts.
It says 10 or 12 cylinder engines only. It doesnt fit 4.2. Have they got one for your engine??

They had loads more - that was the first I came across when searching E-Bay :p

oticed over the last few days that after the suspension failure, that the offside rear seemed a lot lower than all the others.
After if failed today and putting it on the drive I got the tape measure out.
Apart from the offside rear, from the floor to the centre of the arch measured 73 cm.
The other one measured 70 cm.
After turning the engine on and selecting high three of them went to 75 cm while the offside only to 73.
It did eventually raise to 75 cm.

Will keep an eye on it as my drive aint level but it could be a leak or something.
Cheers

Calibration would be ideal in this situation, twice tbh, just to level it up.
But you will need VCDS for it.
You could try the cable I gave you, but if it goes to limp mode cos you can do calibration with this cable, then you will need VCDS.
That isn't a problem because if you need it (emergency) I could always send you my cable via Special Delivery.
Calibration should be possible via this cable as it's nothing really advanced.

There could be a leak on that wheel as well, you could check that with a soapy water first.