Having just replaced Y plenum with new one, and taking it off and putting back on multiple of times I thought i would write a fair warning to everyone, who will either take the manifold off, replace throttle body gaskets etc.
- Audi manual states that bolts, that hold Y plenum down to the intake manifold itself should be torqued to 9Nm. This is bullshit, as OEM bolts are aluminum (they have to be - if they are steel they will corrode the threads in the intake manifold getting them stripped), and they break at 7.3 Nm. In my expirience 6.5 Nm is totally fine.
- Throttle bodies should be torqued to 9 Nm according to Audi. In my opinion this is too much as well. My unit is new, and I dit torque it to 9Nm, however the next time I will do 8, as it is max I was comfortable doing. I think that getting older unit to 9Nm might crack the thing.
- Throttle bodies bolts - I have bought 8 OEM new bolts, and 2 of 8 are just a little bit bent, or the thread is cut in a wrong way - hard to tell. Also all of them have their heads offset just a little bit from the bolt core center. I would highly recommend trying every single bolt first with screwing them in with just your fingers - they should go to the end no issue. If you feel it gets locked just a little than don’t use that bolt.
TL;DR
- Torque for bolts holding Y plenum to the manifold should be 6,5 Nm
- Torque for the throttle bodies bolts should be 8Nm
- Check every throttle body bolt first. It should go all the way in the Y plenum effortlessly.
Hope this helps someone in the future.