Baloo588

How come my air suspension does not lower at all when I put it in dynamic mode from comfort or auto mode while in garage or stationary? I have noticed this for a while now that it only raises and but from comfort to the raised position but does not lower from the comfort level to the dynamic level though I feel the change in the dampings. It used to do this before they replaced my left rear leaking air suspension. Do you think its been leveled and reprogrammed wrong from factory??? There is no fault code or anything.

MP4.2+6.0

Do you have Non sport or Sport suspension?

Baloo588

Hey,

I have the non sports suspension and thought it used to lower before I had the suspension replaced in the left rear last year and totally forgot about it and realized that it looks a bit high even with my 20 inch rims and tires with a bit of wheel gap in auto mode and dynamic mode. I recall it lowered about 10 mm in dynamic since its a non sports. I dont know if its me getting old and cannot see it change height or its malfunctioning.

MP4.2+6.0

Yep, why I asked. Only on a non-Sport should it drop at rest if you dial it down. Sounds like maybe you should recheck your baseline height calibration for starters since the strut work was done and you say visually it looks a little off. I would think it would still lower though, since I think it just operates up and down relative to an assumed baseline it gets from the suspension angle sensors.

When you say no fault codes, do you mean just the dash lights, or a VCDS scan? If not the latter, a scan of the suspension module might reveal something. You would need VCDS to do the height calibration anyway. It can also run through the self test of raising/lowering it on each corner. Happened to see it again when I was checking out coding and mods across modules last week.

Baloo588

Hey thank you for a full breakdown on this. No dash light fault code. I have not done the VCDS scan on the car yet and I called the dealer and told them about this and they will re-scan it free of charge and fix it with a better calibration for me since they replaced that air suspension last March of 2015. I will keep you posted. Interesting that small things in programming can make a difference.

As for the suspension ride its a bit jittery lately and my car has 101k miles and while it runs great I notice that even with the new Michelin tires and the road force balancing the car isn't very smooth on the highway or over the bumps like last year when I swapped out my winter set and I think its my control arm bushings going out. The car gets nervous over uneven strips in the roads and bumps on the highway that makes it sway left and right a bit and is not buttoned down like it should be. I had to replace my upper control arm bushing front and rear on my 2006 Audi A8L at 140k miles after jittery ride with vibrations on the highway that wasn't going away with softer tires and perfect road force balance on new tires. Once I got the new control arm bushings placed in the car felt calm, smoother and solid on the highway and over potholes, bumps, etc.

MP4.2+6.0

Yes, exactly look at the upper control arm bushings like the D3. Or dealer can inspect when you bring it in for ride height check (and bushings shouldn't play into that height or possible compressor or sensor issue). Owning a 2006 D3 and being on that board for 9 years and thousands of posts, I know the bushings issue very well. And honestly I shook my head when I saw the first predictable post here on D4 about them also failing, and another about the MMI screen drive gears. Anyway, at 101K miles I would assume the upper control arm bushings are probably toast. D3's seemed to be 50-80K mile good life, and definite symptoms by 90-100K. When I did mine recently again and got it aligned, car went back to having new car crisp feel.

By chance, literally yesterday I pulled front right wheel on my new-to-me 3K mile S8 to look carefully at brake clearances for wheels for future winters. Snapped picture of that area below--in near as new condition w/ just a little road grime. Looks straight forward to inspect and do. The usual--look for any cracks or tearing. Often shows up on front tires in D3 era as inner tread wear that gets confused with simple alignment. Same sort of pinch bolt (and its freeze up tendencies) as D3, but I see they moved tie rod ends down low so one less thing to hassle with.

BTW, if you have any of the advanced systems where alignment may come into play--lane change and assist or even adaptive cruise for example, you may want to tackle the control arm bushings first if at issue and you DIY. If dealer wouldn't matter. Point is if they decide ride height isn't right, particularly differentially at the corners, it could lead to an alignment I suppose if other systems affected. I'm not so much a true believer that adaptive cruise mandates dealer only alignment, but by the time you get into lane stuff and some others, it matters more. Ride height or especially differential corner errors could play in for some of the systems, lighting control, etc. Not yet up to speed myself on all those subtle interactions on D4 with the advanced electronic driving aids. My D3 with only adaptive cruise and adaptive HID's wasn't ever sensitive to it and I just used my indy tire shop for later alignments.

Baloo588

Thank god no lane change assist or adaptive cruise control on this A8l. I will have my Audi dealer do a full shakedown on the suspension next week. BTW, we have a 2014 Audi A6 TDI that I applied for a goodwill package (500 dollars dealer credit card and 500 dollar visa card) so I can use that money towards any necessary repair on the control arm bushings. I will keep you posted!

Baloo588

Hey did you get small vibrations throughout the car with worn or cracked control arm bushings that is felt mainly at highway speed even on smooth tarmac even with perfectly road force tires

MP4.2+6.0

Yes. Front end basically just felt somewhat looser and yes, also prone to some slight wheel shake that you would really think was a balance issue. The vibration was also temp dependent and sometimes felt w/ some braking. But it wasn't tire balance (BTDT). All resolved way better immediately post bushing (and front sway bar links at same time) work. As soon as I left alignment shop and hit the freeway, I smiled as it felt near new again even on my well worn Dunlop summers.

Baloo588

Great! I feel loose in the front and some shaking not tire balance related and some pulsation when braking even with perfect and round rotors and brake pads. Im getting the bushings inspected and replaced this Wednesday. Cannot wait till to have that smile after hitting the road on my recently placed on Michelins and with my new bushings.