After some recent mods, I noticed by manifold boost pressure is not reaching target levels as the rpms climb. I found some very interesting info on the other "list" about the ECU effectively capping power. My car is reaching target boost levels pre throttle, but post throttle the pressure is bleeding off. I performed a boost leak test from turbo outlet to turbo outlet and everything was holding pressure up to 22.5 psi. The logs back this up showing pre throttle boost pressure at or above target levels, only after the throttle and at upper rpms does the post throttle pressure drop.
The turbos are capable of producing 20+ psi and the manifold is capable of containing it as witnessed by the log showing between 19 and 21 psi from ~3800 to ~4000 rpm as the pull starts.
Setup:
2008 997 turbo cab 6MT
stock airbox
stock turbos
Cobb Stage 2 93 octane OTS tune
do88 inlets, ICs, and y-pipe
FVD headers and catted exhaust
Max IAT 77* F
0 knock retard

Full log here:
http://www.datazap.me/u/vman932/data...18-24-25-28-35

zoomed log here:
http://www.datazap.me/u/vman932/data...8&zoom=143-187

What say those wiser than I? Boost leak in the manifold? Weak/leaking diverter valves? ECU shenanigans?

 

I remember going through this when I started learning about my car as well. That value you are asking about is a modeled value. So why model it instead of using another sensor? Because virtual sensors are cheaper and they don't break, no warranty. Us working in industry get a lot of encouragement to get rid of physical sensors. Sensors are one of the highest warranty items across the industry.

When engineers make these models they are suppose to be accurate within the expected airflow the engine will have. Once guys like us turn up the airflow lol, it's being extrapolated. So you are reading 20ish psi in front of the throttle body the virtual sensor says at this higher airflow I expect to have x amount of delta pressure through the throttle body thus the plenum must be at this lower value.

I actually turned off this channel in my datalogs but just for fun I'll make a pull with it back on and post it on this thread. It should be pretty bad now lol. I'm flowing 490-500grams per sec with my current setup. This is where I wish I had full access to the ecu I would correct the model to represent my larger throttle body and know what the engine is actually seeing. There is always some loss.

Hopefully that helps you feel at ease.

 

Haha, yep. Just answered this on the other forum. I went down this rabbit hole in 2014 when I was putting my car together.