So I changed out the AOS last weekend, and holy crap I should have done that sooner. It transformed the car, and has apparently been bad since before I bought the car in 2017.
It wasn't smoking noticably from the tailpipe or anything, and for most of that time it did not seem to be burning oil in any noticeable quantity, but it did always have the oil smell coming from the area of the intake duct after a good thrashing, and a very slightly wobbly idle. Those two symptoms are now gone, though it did take a while for all of the oil to burn out of the intake and the smell was actually stronger the first few times I drove it after doing the job.
Other things that changed.
The car has always had a strange tendency to suddenly stall at creeping speeds like backing into a tight spot. There would be no warning, the car would be doing fine and then BANG, stalled. It made me feel like I forgot how to drive a manual. It was also rather tricky to get off the line, especually in sport mode. Nearly every person who has ever driven the car has stalled it at least once. I thought it must just be a reality with a lighter reciprocating mass like these engines have. Nope. It was the AOS apparently, as that symptom is completely gone now. The car can even recover from being slightly bogged now. Before it would have stalled long before it bogged down, so I never even saw it bog before.
Low end torque is vastly improved. Previously, torque at anywhere under around 3,000 RPM was pretty pathetic. I always just thought that was a reality of a high revving engine. It's much better now, which makes putering around in small villiages and the like here in Germany at 30 KPH a lot more relaxing as I can now leave it in third rather than having to drop down to second.
Overall engine smoothness and power is also improved. It always felt like a smooth engine to me, but now it is next level, and the characteristic of the sound is also more mellow, especially when cruising at high speeds on the autobahn. I find myself just cruising or slowly accelerating through a gear at high revs under low throttle when there is no room to stretch your legs, because it just sounds so damn good now. It feels like it is still improving the further I drive it too, maybe the adaptive electronics ares till catching up to the change?
Best guess is that there AOS had a slight tear that was allowing some air through and messing with fuel metering measurements. Anyone have any more concise info?
