c15 at 525 setting is still weak to me. help please

Check the line to the wastegate, they are knowen to rot and leak. The ecm will log a fault over 33 psi of boost. If the line is leaking, the wastegate will not open resulting in a overboost fault and derate. I have also seen this fault from injector codes 5232 and 6999 due to the fuel rate is increased about 2 gph.

If you are not logging any faults or events, I have seen camshaft timing lash cause a active camshaft to crankshaft fault, this will turn on the check engine light but will not be a logged code or event. If you shut the key off the active fault is gone and not traceable. I have had this before and was hard to find until the customer returned with the light on and I found the active fault.

 

If you have a Cat dash display, the display is read what the ecm is reading from the boost sensor.

 

I also am running a C15 MBN and my manifold pressure never gets about 30 psi of boost.

I sure hate that lag I get when going through the gears pulling a load. I will loose 3 mph before it starts pulling again.

 

The engine will get high boost if the fuel flow is there, is it possible that 5232 or 6999 is in that engine. Has the FLS and FTS been changed? Your complaint is the check engine light comes on and derates during a pull, 36 psi will cause that. Do you know what fault number it is, it may be the boost control solenoid is failing resulting in the overboost.

 

Better go with the later 7CZ file then.