Midwest Farmer

After all the trouble, it ended up being the boost pressure sensor on top of the intake just behind the intercooler.  I had replaced the sensor on the rear of the intake near the firewall, but it was the other sensor.  Hope this helps someone else in the future.  

Sometimes the truck will do it with lower boost, maybe around 30-35psi.  It seems like it’s worse when the truck is fully warmed up.

The next thing on my list was to attempt an actuator calibration.  Is this something that could be freed up, or does it likely require replacement?

I’ve looked all over and can’t find anyone with the same problem as me.  I’ve got a 2010 cxu with the MP7 with around 320k miles.  I bought it used from CIT.  Had some serious boost leaks and several  sensors needing replaced. It now builds 48 lbs of boost but will randomly ”pop off”, it blows a puff of black smoke out the exhaust and drops a few pounds of boost according to the gauge.  I made a device to pressurize the system and check for boost leaks and also temporarily blocked off the discharge valve to eliminate it.  I found and fixed an o ring leaking on the elbow coming off the turbo and the small hose at the EGR cooler.  It has no codes and no mechanic has been able to solve it. Also, it does black smoke accelerating under load... which it shouldn’t... thanks for any help.