if your tps isn't showing as being at closed throttle, or your map isn't reading full vacuum, your injectors may still be firing on decel.
this could also account for the CEL, since your o2 sensor should read full oxygen on decel. (not that it can, since it's a narrowband, but you get the idea.)

 

smoke on decel says valve stem seaals or rings, your ---- is rizoasted *****

 

also, if the cel is flickering, is anything else electronically strange? check your grounds.

 

you could have just weak rings, comp check it to make sure its ok first.

if you get a solid cel, find out which one it is.

did you mess with the base timing when you installled the kit? could be off

 

popping durring decel is ur timing. i burnt all my valves cuz my timing belt ripped its teeth out.

 

either that or a really loose internal wastegate flapper, do you boost ok or is it all over the place and laggy?

 

**** isn't dumb, and smoke on decel with a shitty turbo happens all the time, there just isnt as much exhaust flow so you can see the smoke easier :-P

 

this motor is brand new guys, 7K miles, 210psi comp across the board.

interesting thoughts on the tps, but id find that hard to be true, z6 tps sensors are riveted on and cant be adjusted.

im bout 100% sure the turbo is toasted, not much in out play but side to side is outta hand on it. The other things is I don't have much of a downward angle on the oil return, stupid 14b's.

 

get a new turbo... dont ---- around if ur motor is new.