2013 CXU613 Won’t Boost Over 15 PSi

[Oldfield]

Hi All, I need your help…

I’ve been trying to figure this out for the last year. My injector cup was bad. I kept driving the truck and one day I saw a white smoke so I put it in the shop. When they changed the injector cups, they adjusted the valves to the wrong specs. I adjusted them to the right specs. Going uphill, loaded or with an empty trailer the RPM drops and it won’t make more than 15 pounds of boost. I’ve changed the boost pressure sensor, cold air sensor, had the DPF filters cleaned, EGR system cleaned and replaced the turbo/V,GT. With the new turbo and VGT, when the replacement VGT kicked in the motor would choke as if it was not getting air. I had the VGT recalibrated and they were able to stop the choking but the boost was even worse. I brought it back and they re-calibrated it again. They were able to get it up to 30 pounds of boost, but it was choking again. I’ve also changed the fuel filters and had the DEF and DPF deleted. I had it at a Mack dealer; they checked the fuel pressure and said it was within spec.

I really need to get this sorted out. Any help is greatly appreciated.

[Mackpro]

Mp 7 or MP8’s and what year model . My thoughts are a stuck open EGR valve which will drop turbo wheel speed and low boost for starters 

[Oldfield]

2013 cXU613 MP8. It’s deleted (the EGR pipe is sealed)

[Mackpro]

If it ran good before the injector cup fiasco then I’m wondering if something is wrong in the upper end. Engine brake valve sticking open. Engine brake plungers backing out . Or engine valves bent or not sealing. Valve adjustment off.