6.5L no boost
 

I have a 95 6.5, with no boost. I used to be able to hear the turbo when I would step on it in the cab and hear the wastegate open. Now I have no boost and I was wondering what could be wrong. I put a new vaccum pump on and I still dont have anything. Could it be the wastegate or the boost switch? Also going down the road from 2000rpm to 2600rpm and I hold it there on cruise it throws a code and if i accelerate or slow down the code goes away. Any information would be greatly appreciated.

Pull the codes. Should be 78 IIRC. Probably got a bad sol but check the wires going to it first. Also check all the vac lines.

I have had the same thing happen too me it was the acc on the drivers side rocker cover.