Pothole5000

That is a S4 4.2 which is different than the one in the A8.

dvs_dave

Rear mounted timing chains debate aside, how about Gen. 1 direct injection system fun and games?

It's reasonable to say that the old 4.2i timing belt motor is the more bullet proof lump that's had virtually all kinks worked out of it in terms of reliability and system weaknesses.

But then I would say that because I'm obviously trying to make myself feel better that I don't have the newer version. Although "newer" is a bit of a misnomer considering that we're talking about a vehicle that was discontinued in the previous decade.

MP4.2+6.0

Trouble with the FSI argument is high pressure direct injection isn't really "gen 1" technically. Think diesels. Having had the joy of working on an original Rabbit non-turbo diesel with a mechanical fuel pump, that was gen 1 for VW/Audi as far as generic high pressure fuel delivery into the cylinder. I'll grant some valve fouling on FSI/DI, but once again not so much on the D3 A8 4.2. More an S4 issue w/ that flavor of FSI motor, and a lot more with 3.2. Or even the S8 V10 unfortunately to an extent.

They all have some weaknesses and idiosyncrasies. I owned a pre-FSI belt drive 4.2 for 15 years with my C5. On the pre-FSI belt drive 4.2 specifically, the thermostat and water pump inter ties right there in the timing belt drive are really an abomination which should never have happened or been allowed to remain if "virtually all kinks worked out of it in terms of reliability and system weaknesses." Maybe with the timing belt set up is the unfortunate cross over to other Audi motors that as a practical matter has left distribution channels for aftermarket parts really clogged with junk and dubious quality parts and lots of owner let downs. I also think the multistage manifold in the longest run will prove out to be an expensive Rube Goldberg kludge for some.