We put on a new exhaust system on a buddies of mine last week. this is on his 2001 F350. We added a 4" exhaust system on it. He has no other mods on it yet. We put on the exhaust and it ran like crap and had no power. I was like WTF is goin on here cause I had the same symptoms on my 99. I hooked up my Boost guage and we were getting 4psi of boost. We checked his turbo for leaks but it was running fine before the exhaust upgrade. We started looking around a day latter and noticed there was an arm on the bottom side of the turbo on the exhaust side was disconnected. Im not sure what the proper name of that arm is but I think it is for heating up the engine. Well we put it back on and the truck started running allot better again. It ran good for about a half a day then started having problems again with Power and black smoke. We thought that arm had come off again but it did not. We were back to square one again with a power loss. We checked the same area under the turbo and could not see anything wrong with it. Then we brought it to a diesel shop and told them what we did and where the original problem was. What happened is when my buddie was pulling off the turbo clamp he smacked that rod under the turbo. Well something happened inside of the turbo pedistal housing where that rod goes. I dont know exactly cause I was not there when they did it but my buddie said something snapped. the place just happened to have a pedistal from another truck there. They put the used one on there and has worked perfectly. The guy there said if you think your running low on boost you should always check that cause sometimes those rods vibrate off.

Just some usefull information that I wanted to pass on.

 

i think you are talking about the exhaust back pressure valve(EBPV) and if, for what ever reason, it does not open it will do just that

 

Thats the name of that piece. Thanks.