No mods are done I run 91 octane and I never heard any pops or anything but I just know when it left the dealer I was boosting at damn near 20 psi and I can’t get close now. Been super hot here lately but I don’t think that would cause 8 psi drop from heat but I am new to the turbo world also so not sure. Thanks everyone else actually giving me some advice or things to think about lol
The boost value displayed literally means nothing as the ECU doesn’t target any specific boost value. It’s probably best to ignore it.
The ECU utilizes a series of Driver Demand tables to target the related Load, Torque, and their related limiter tables to produce power. The boost value isn’t included in any of the power demand tables. The manifold absolute pressure isn’t either. They both are utilized as limits, not targets.
As FTO mentioned, the ECU will limit power by decreasing the Load and Torque targets related to specific Driver Demand inputs depending on the derived octane level which is itself based on knock sensor data and related timing advance/retard tables. The result is lower peak indicated boost (manifold absolute pressure minus barometric pressure) to meet the lowered Load/Torque targets.
The ECU also has many Load/Torque limiter tables that utilize intake air temperature and manifold air temperature to reduce Load/Torque targets.
Bottom line is back to my first statement, the indicated boost value is literally irrelevant to performance, unless you have a related fault code.
If you’re interested in learning more about the ECU function you’ll need to get much more involved in the Ford tuning software.
In the “old days” before electronic engine management systems, the indicated boost told you something important, directly related to engine power. Now it’s just not really
important at all unless it’s way too high at the peak Load/Torque value.
