Hey everyone, I want to say thanks for all the extremely helpful info on here! I have a 99 F-250 CC with the 7.3 and 246K on it, no boost, EGT or tranny temp gauges as of yet and auto transmission. Everything is stock except the two mods I have - 4" exhaust and superchip turner set at setting 2 of 3, I forget what that mode is called.

This just started about a week ago. At normal acceleration the turbo whistles just fine and no loss of power. But if I put my foot in to it to pass someone, or get sick of waiting for that perfect opening and pull out in front of someone and want to get up to speed quickly, the best way I can explain it is that when the boost starts to get high it seems like the wastegate just blows open and the turbo whistle sounds very abnormal and there is a huge loss of power - this is during fast acceleration at the high end, not a quick release of the pedal.

I can then just let off and continue driving under normal conditions and everything sounds/works fine, it just happens when I mash on it. There is no grinding sound coming from the turbo, so I assume bearings are fine yet.

Any ideas are greatly appreciated, I would rather troubleshoot this here and benefit our forum than pay the diesel mechanic $80 just to troubleshoot it.

 

Sounds like turbo surge to me. Search threads for turbo surge. You should find a vid of the turbo surge. Install a wicked wheel and you should be good to go.