Turbo prob need help urgent

[Benny C]

its a 98 toyota landcrusier factory turbo diesel inline 6,
everytime you hit 4000 rpm the boost goes from 12 psi to neg
12 psi and blows a sh*t load of white smoke what the hell is going on

[dow50r]

The choking valve is applying in the intake on top of the tappet cover....the puter can apply it if the motor runs away...why do u need to rev that high??

[balzackracing]

20 bucks says your intake piping from the filter to the turbo is blocking off due the amount of vacume. See if you intake hosing is soft and has signs of kinking or remove you air filter and try again.(Removeing the air filter will reduce intake restriction, just clean your air box out before you try it so you don't dust the engine). Same thing happens on some of our older mining gear that dont have intake restriction gauges fitted, usually because the air filters are chockes.
Cheers,
Busty