Hi, I have a NB 1.6 transformed into a turbo, as soon as I turn the car off when it's hot and turn it back on after a few minutes the car grumbles when accelerating, it doesn't rev up and the turbo pressure doesn't increase, as I gradually insist the car becomes efficient again. I encounter the problem both if I turn it off when hot or keep it at minimum rpm when hot, ONLY when the engine is hot. what could be the problem?

 

Heat soak of the inlet air temperature sensor can do it. Improper tuning can also do it.

You made no mention of your ECU and have not posted a copy of your tune, so further help is not possible at this time.