05 ISX 565 Surge, loss of power, ideas?

[Chelleb518]

Hi everyone thanks for letting me into this forum. I drive a 9900 with ISX 565. A few months back I started to get turbo noise, truck ran ok but replaced before it became a bigger issue. Second turbo was D&W and was noisy with just a few days out of the box, dealer replaced with a 3rd warrantied unit which is the current turbo on the vehicle, the truck now is surging under load. On gauge boost ranges from 5-50, hovering between 25-30 sometimes but for the most part stays up past 45 and falls on its face when reading in that range, rpms won’t exceed 15/1600 when boost is past 35.


CAC was replaced 6 months ago, and our “house” tech has found no other obvious leaks. Bobtail the truck runs fairly well unless presented with a large incline. Once you add a trailer to the equation drivability goes out the window. Even empty this truck which is normally a pretty decent beast struggles to get to 65mph on the flat. Fuel filters regularly changed, breathers checked, I know they pulled a few electrical components and swapped with new but I’m not sure which (I can verify tomorrow at work).

No active codes.


Any ideas? Please be gentle, I’m not even remotely mechanically or technically inclined, but I love this truck and want to get back on the road