rancona

So I have the devious wastgate rattle. I ran the car with a boost leak for a bit before putting on a catless downpipe and now the rattle is here. The car threw an underboost code, but it still makes power up top once the actuator pulls the wastegate closed. The wastegate rattles bad off throttle, but the second I even touch (<1 cm in) the rattle completely stops. I went to replace the actuator, but the rod felt extremely tight, and also, I had the wrong actuator (buyer beware on ECS tuning). Could this be a case of a bad N75 valve? The car is exactly a
2010 Audi a4 6mt with a
catless downpipe and axleback dual muffler delete.

SMac770

Forge actuator? Forge actually advertises the wrong actuator for our car.
This is what Forge incorrectly advertises for our car: https://www.forgemotorsport.com/Turb...oduct--60.html
This is what our CAEB motor IHI turbos require: https://www.forgemotorsport.com/Turb...duct--105.html
I suspect you might be able to make the A4L work using one of these: https://www.forgemotorsport.com/Actu...duct--122.html

The N75 I doubt is very complicated. There's no vacuum involved. It simply passes boost to the actuator, which starts to move at 4 psi and should be fully moved (1/2 inch) just over 10 psi. Not really sure why it has a line back to the intake before the turbo. I assumed the electronic connection was for control of to pass or not pass boost from the post turbo connection to the actuator connection.

As for your wastegate, maybe it's loose (when you had the cat off, did you play with the wastegate cover to see if you could easily rotate it?) and with just a little gas it gets enough pressure to push it away from the wastegate hole so nothing to rattle on. The actuator rod itself is usually not a problem. It's play between the actuator rod and the link to the wastegate swivel, or play in the bushing that the wastegate swivel moves within.