First air suspension issue

[M-A8]

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][/IMG]

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

[IMG][/IMG]

Then lift and 2.28 bar

[IMG][/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][/IMG]

...and comfort just over 3 bar
[IMG][/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][/IMG]


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

[Delboy]

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.

[mannyo]

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

Looking at that last picture.



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.

[M-A8]

Originally Posted by Delboy

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.

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

Please do Del

Manny, can you post your live results??

[M-A8]

Originally Posted by mannyo

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

Looking at that last picture.



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

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

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

[mannyo]

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.

[M-A8]

Originally Posted by mannyo

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

[M-A8]

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

[HPsauce]

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?

[M-A8]

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.