Cummins ISX VGT hunting

[Joesixpack]

Hi, long time no see and forgot what a great resource this is.
We have a 2011 T800 with a ISX and lately the VGT turbo is hunting I'll call it, does an oscillating closing the vanes and boosting up then dropping over and over during light load, it just don't seem right either if you find a happy medium where it isn't oscillating and acts constipated and boosting to hard for the load and not running free.

I did change the MAP sensor and it didn't effect it. I suppose the next up is the VGT controller? It's not throwing any codes but the truck is deleted and who knows what it's letting through.

And of course my Insite isn't working! Been a long time since I needed to plug it in!