I recently have been driving around town never really exceeding 40mph and trips no more than 10 miles. Since then i have been hearing strange almost grinding noises up by the turbo.
The noise sounds somewhat like a grind as boost builds and more and more like turbo whistle as it spools to full boost and is excessively loud.

The other day after about a month of just city driving i finally drove on i90 and as i was about 50% acceleration in 5th gear i blew my boost hose loose at the compressor exit.

After that i put the hose back on and drove back, running a bit lean ever since.
Instead of around 14.7 I've been sitting at about 16.0 at part throttle and idle and then as it spools it will drop down to the 12's during full boost which is lean.

During low spool and low rpm the power is a lot less than before.
and is very noticeable during cold engine

Things i have done to trouble shoot.
Re flashed the ecu with my tune.
Pulled the intake and checked the compressor side.
The wheel looks flawless spins freely absolutely no shaft play.



My Three theories i have are is that

A. Something CV joint related. - But makes me question because once it hits full spool the power is there.

B.The turbo may have some issue that is not apparent.

C. This leak in the manifold is contributing to the cause.

 

the comp wheel may be fine, but how about the turbine? are you running a cat (perhaps the catalyst has fallen apart and is rumbling around)? check for pre turbo, post MAF (if you are running one) air leaks. What is your vacuum like?

The leak in the manifold is probably a leaky valve seal. I have a similar leak

 

Vacuum is good and normal at -20, idles not bad either.


The compressor turbine looks great.
I got the exhaust manifold welded up today and the low end torque is back and spool is better, but the afr is still slightly lean.
I'm gonna run some logs tomorrow.

 

how about a cat though?

 

i currently am running it cat-less.

 

Figured out a large part of the problem! Where my turbo bolts up to the manifold the nut was missing on the stud.
It was like that on the other side also causing the whole bottom side to leak exhaust out.