Check the connections to the EGR valve, if either the vacuum pipe of electrical connection are damaged / corroded then the EGR can be on all time which certainly will hurt performance. Its also possible that its a fault with the EGR valve so its worth removing the valve and cleaning it out with brake cleaner, if it looks particularly clogged then replace it.
If this is OK then check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issues and its best to have the boost pressure measured actually measured with a boost gauge to check that the turbo is healthy and that the sensor is reading correctly
If its a variable vane turbo (they’ll be an actuator on the turbo body - but not a wastegate) then check its vacuum pipework as above and check the connections to the diaphragm / solenoid valve
Also check all the high pressure hoses post turbo/s for any split hoses or cracked metal pipes, also check the ends of the intercooler as its not unheard of to pop the end caps off under high boost.
sorry if I didn't make that clear, the white smoke will be unburnt fuel
so its likely that there's a lack of air or boost pressure leaking
hence my suggestions of above
I woudl have hoped he has already checked what I suggested
it could be the pump
if the timing of the injection is off then this too will produce a lot of white smoke
has he offered any particular fault or its just a faulty pump?
in that case I'd check for the air leaks / boost leaks as I've 1st suggested and get back to me
do you still need help?
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