I have a 2500 CC SB 4x4 with 101,000. Have a Fass 95, Racor 2 micron, muffler delete and Edge w/ attitude CTS. Been chasing my tail for months now. I just changed the factory and the 2 micron filters coming off of the Fass. I test drove it and had good power and turbo seemed to spool faster. Truck sat for a couple hours and took it out again, same as before... This truck sometimes runs great and is a dog at others. When it is running good I give less than 1/4 pedal get 20-30+ psi of boost and it feels good, kicks you back. When its running like #}%! it needs a lot more pedal to get same boost and go. Either way I can see 35psi on the edge and mechanicl boost gauge. The truck has no blowby, good return rate, no morning hard starts, oil analysis from Cat showed less than 1% fuel dilution, doesnt make oil and idles perfect (no lope and stays at about 750 rpm). Rail pressures are: 6500-7100 at idle, 18-19k cruise, 23+ at wot. Boost no matter how its running builds good but I dont know how long that boost should maintain. Could a faulty wastegate be dumping boost occasionally? I cleaned the map and iat sensors, no real change. Someone told me FCA, but it doesnt die or idle poor. Any ideas? Shops I have taken it to just want to replace stuff randomly, I dont have the $$$$$ to do that.

Also, one shop drove the truck with a scanner hooked up.. Said he noticed the hesitation (almost like it was starting in the wrong gear) but saw no reason from his computer, thought truck was great otherwise. He felt the gear changes from 1 to 4 so he was puzzled also. Thanks!!

 

Have you tried driving around for a while with the edge off the truck?