Originally Posted by
Bugasu
Desired TIP controls the wastegate, Desired MAP controls the throttle. TIP Actual over TIP Desired will naturally close the throttle as your Desired TIP > Desired MAP (because of throttle loss).
If you want the throttle to stay open for some reason, you need to move TIP Desired out of range of what your wastegate can actually do. Of course the wastegate PID system will fight you for doing this, especially I-Term as it tries to ramp WG up for the TIP Error. So you need to recalibrate pretty much everything to get that to be happy.
And then, you have to make sure you're close enough to TIP Desired to not actually get an underboost code, or again move that out of the way.
As well, lets say conditions line up (it's cold, you're at sea level, etc) and now you suddenly can produce that TIP Desired. Now you're going to be overboosted and have more load than you probably want. The WG system is not designed to target a set airflow, its designed to target a set TIP that derives from an airflow, which will be constantly changing based on external conditions. Set boost tuning is inconsistent in the airflow realm, which is why OEMs don't tend to use it anymore, and the Ford ECU is not designed with raw compensations on the wastegate signal to do it. Can you hack it? Sure. But why?
Why not tune like the OEM and have both WG and Throttle helping control MAP and not worry about any of that, using the logic for its designed intent. Having two ways to control something is better than one, especially when one is fast (throttle) vs the other (wastegate). Why do you want only one way to control it?