hi all,
Long time lurker of posts, thank you all for the vast knowledge on here, I've used info many times, it is my First time posting;
So I have a 2006 CXN613 vision , with AC460 CEGR engine.
I have been having intermittent low power/ low boost problems with the truck, sometimes truck pulls great and makes 30+ psi boost, others can't get the truck to hold 5 psi. Seems to happen more frequently after about 1hr of use. I've had the truck to several garages, all to no avail.
Some background on what has been done:
I have checked for loose wires at eecu connectors (as this had been a problem causing truck to shut down while driving in the past)
I have replaced and calibrated fuel pedal, all good.
I have checked VTG operation visually and while driving with a GoPro, all seems good.
I have disconnected and pressure tested charge air cooler and piping, no leaks.
Fresh fuel filters, air filter, no fuel restrictions
No current active codes (getting an occasional 6-4 flash code, but not corresponding with low power occurrence.
I have replaced boost pressure relief valve, thought this was my issue as I tested it and it was weak, opening at 3-4psi; when I replaced valve, after first startup the truck sort of coughed and ran rough for a second putting out blue smoke, test drove the truck bobtail, it pulled like a race car (maxing out boost gauge I installed) , I was excited thought I had issue resolved. Truck went to work the next day, ran great for about an hour loaded then lost power. No codes present.
Anyone have any suggestions on where I should look next.