I’ve been running my boost off nothing but spring pressure at about 14# so I think this might be a good starting point, the spring sill provide ~60-70% of max boost and the n75 can do the rest .
So Today I before work screwed around a little trying to enable the boost control so I can turn it up finally to where it should be . No dice yet as I can’t get the n75 to click or do anything . Yet if I plug it in it goes for full boost and does not allow the wastegate to open .
My goal was to start by going strictly off duty cycle for now , with the RPM vs RefDC table . that way I can slowly move the DC up and figure out what given duty cycle curve I need to reach my target boost of around 20 psig
I have the N75 plugged in and using the TiAL MVR wastegate , n75 line running to one of the top air ports (nothing on the bottom air ports) and the other n75 “Vent” port (that normally would tie into the urs4/s6 intake elbow ) to atmosphere .
Now I went in and set P,I,D to 0 and changed the boost control to “RPM/gear/speed based” so I can use the RPM vs RefDC chart to run the boost.
with the n75 vented to atmosphere I should hear it clicking but I don’t hear anything if I try driving the car like this , the boost will go way past spring pressure as if the n75 is not interrupting /venting the signal from the manifold reference line . It acts as if the n75 is requesting full boost . I went in to look at my settings , and I don’t see anything off but I must be missing something . I tried 0% duty cycle then tried 100 to make sure it is not inverted somehow




Don’t know if those pictures will even be legible
I know some outputs in VEMS there is a way to “invert them” but I could find that box for this one
On the way home from work I unplugged the n75 and still had high boost instead of spring pressure . So the failsafe should be opposite of what I am seeing . I basically have boost pressure holding the wastegate shut . Maybe it’s my plumbing .


Go figure in a 3600 sq ft shop of Audi cars and parts I don’t have a single spare N75
I may try to reconfigure my wastegate to this (shown below ) I don’t understand why the bottom line , direct connection to lower air port is needed but even the TiAL instructions say to use the bottom ports

