maybe turbo? maybe wastegate
 

i have a 2006 cummins. it had a cracked exhaust manifold when i bought it. just a quick fix, but when i fixed it i noticed the turbo wasnt as free as id like and there was what looked like oil or soot in the face of the turbo. and the fins had small dings in them. i noted the problems but decided to finish the manifold replacement and put the turbo back in and keep an eye on it. but when i took it for a test drive, when you drive it like youve got your grandma it runs fine, but when you mash the gas like your trying to pass someone it falls on its ass andthe second it falls theres a slight whistle like the wastegate unloading. as long as the trucks running at 1/4 throttle theres nothing wrong, but as soon as the turbo starts to spool its just loses it. maybe its the wastegate, hopefully not the turbo. any help would be appreciate it.

Do you have a boost gauge on it and if so is it reading anything at all at quarter throttle. Is there a lot of black smoke out of the exhaust?

If there are small dings in on the compressor side, chances are the turbine end is worse.

Any updates??

check the boost and also check the wastegate to make sure it is holding closed

Closing due to members last activity on 8-3-09.