Throttle closures on 3.0? Read this
I've been seeing a few posts about people trying to raise boost unsuccessfully on some of the 3.0L (and probably newer 3.5/2.7 strategies as well). I spent some time looking at the code and wanted to quickly write about what is likely causing the issue for most people.
The desired airmass logic is a *huge* function, and despite what the "Desired Airmass Initialization Switch" would suggest, there really isn't a way to avoid it's influence on the final airmass requests and throttle control. I'm trying to condense this so here goes nothing:
I think a large portion of the confusion is that the "Desired Airmass" and "Desired Load" scanner parameters are inputs to the desired airmass logic, not outputs. This means that those values can get clipped by desired airmass and often not be easy to spot. "But wouldn't my Throttle Angle or Torque Source change if I got clipped?"
Not exactly. The parameter you really want to watch is "MAP from desired airmass". This is an output from desired airmass and what actually ends up regulating your ETC. Most often it gets clipped by one of the TIP Maximum limiters (turbo speed, compressor outlet pressure, compressor outlet temp, etc.), because obviously MAP cannot exceed TIP. There's also a lot of turbo limits that are in airflow units, but most people spot those more easily. When this happens, you won't see a change in Torque or ETC Source because it isn't really a limiter stemming from Torque or ETC control, it's a TIP issue.
So, log "MAP from Desired Airmass" along with every TIP Max parameter you have, chances are you'll find something there. On some of the 3.0 calibrations, it seems that the compressor outlet temperature limits are modeled to be awfully close to the stock boost levels.
