PIMCO

Hi, good folks!

Considering a '07 S8 5.2L with 140k miles, and was hoping you could fill in an Audi illiterate like myself. The car's service records are somewhat irregular, stamped @ 25k, 50k and 100k. Beyond that it appears maintained and well equipped (lacks ventilated/massage seats and the ceramic brakes, AFAIK).

There are however two issues I would appreciate your opinions on. First being, I noticed a tendency for the drivetrain to 'bind' or 'drag' (no mechanical noise as far as I could tell, but it would probably chirp tires at higher speeds) during full turns on hard (pavement) surfaces. Is this common? Also, I was told the check engine light had appeared on two occasions when accelerating by manual shifting and high RPMs. The error code was associated with a lean fuel condition (pump not able to deliver enough fuel?), according to the dealership. Is this a familiar hiccup or part of a more grave issue?

Further, what are some of common faults and problem areas on these vehicles that one should pay special attention to?

Kindly awaiting your feedback.

richard-tx

A bit of tire scuffing is to be expected with a car of that length and is perfectly normal when making a very tight turn.

The CEL light and overly lean condition could be the fuel pumps as the dealer said and seems likely.

Junius

Yes I believe the binding is normal on our cars since it's all wheel drive. It's the Quattro system working.

PIMCO

Thanks for the feedback.

I've had Range Rovers and Jeeps with permanent 4x4 that squeal less. Was somewhat surprised to learn that Audi's flagship land yacht doesn't have a more refined four-wheel drive delivery system. I understand this year feature a Torsen centre differential/transfer case with 40:60 power distribution? Does it require additives in the gear lube?

So, is really sooting/carbon build-up in motor the largest practical issue with these vehicles? What about the sealed-for-life tranny fluid?

dvs_dave

Range rovers and jeeps etc have open center diffs with a simple on/off 100% lock feature. It's not like a torsen diff as used for quattro which is a torque biasing type that automatically varies the torque distribution between axles on the fly and is better for on road performance rather than off road.

Minor downside is that during low speed tight turns it starts to lock up slightly due to the different front to rear axle speeds. This can cause a grumbling/binding sensation in the drive train. At higher speeds and less sharp turns it's not an issue. It shouldn't be squealing tires though which may be as a result of a suspension or alignment issue.

By all means change the transfer/diff case fluid but don't mess around with adding additives/friction modifiers as torsen diffs are very sensitive to it. You might get rid of the grumble, but it also ruins the torque biasing function of the diff and makes it at act more like an open diff. You won't notice day to day, but the core of the Quattro systems performance is now jacked.

Regards "for life" ATF, that "life" according to ZF the tranny manufacturer is 80k miles or 8 years, but Audi won't admit that. If that S8 car is on the original fill, the trans will benefit noticeably from a fluid a filter change.

the_duke

Carbon buildup can be a problem with the 5.2 engine in the S8. Also some have had issues with the intake manifold flaps that can result in the need for a new manifold. They are not cheap. Personally I would have the car checked out and a scan done by a shop that specializes in Audi cars.

+1 to Dave's comment about a trans fluid/filter change.

Giovanni Giovino 6.0+6.0TT

It may be alignment, my A8L W12 had never squealed before, I would take some on/off ramps at high speeds (80+ 3AM just me and empty roadways ) and she never made a sound, just recently after I replaced all front suspension parts and wheel bearings, I took it to a shop for an alignment, well now it squeals like I am dragging a locked rear wheel at even 40-45 on a tight ramp, which it never did before, and my Jeep GC Overland does not make a peep, nor does the Range Rover, I will be having the alignment redone, as I can tell by the before and after sheet that he in-fact did move the rear around, and the front he did not do properly as he said "I am NOT loosening the sub-frame even though it is a requirement"......

Jack88

Well, that's more than a little irritating, I'd bet, Gio.

Howaboutthat

No Torsen squealing, here. I did have the tranny fluid and filter swapped out at 80,000+ miles, and had the top end cleaned of carbon. No other issues aside from the cold-weather suspension groan over bumps.