Ive had similar symptoms and it turned out to be my boost control, except i went from ebc to mbc and that worked. sounds like you are already on mbc, but it could we worth a try. I was boosting to high 20's though.

 

i tried going from like 20 to 16 but no difference.. has to be the exhaust leak..

 

Someone else with the same problem as me! woo!

Are you internal or externally wastegated? Few people pointed me that route, but I'm external wastegate on my setup. I was gonna try new plugs too and regap them..

But the exhaust leak sounds like it is going to be the culprit for me. Mine leaks from the front where the turbo mates to the manifold, and I could hear/see it when I turn the AC on it hits the radiator.

Shall just pop the turbo off and swap the gasket and cross my fingers! Good luck OP!

 

Well this is embarassing, 3 months of not caring / kinda trying to find my sputter issue, go to take off the turbo... 2 bolts are finger loose... tighten the two bolts. and go for a beat down run, car runs like it did before, boosting fine pulling like a freight train.

 

haha nice!! what bolts were loose?

 

What kind of plugs are you running? Also what BOV are you running?

 

plugs didint make a difference when i changed them.. a hks ssqv. havint really got time to check for leaks or anything yet.. studying and working 24/7

 

check your bolt where your exhaust manifold bolts to the head and where it bolt to the turbo, and also look for black exhaust that looks like it was escaping and all over in them areas.. if thats not the problem id say may p0300 or do you not throw any codes?

 

no codes. i tried the manifold one was kinda loose on the very left side there is black stuff. tighted it and still the same problem.. its weird some days it does it really bad and other days it does it a lil bit.. will check other places one this damn rain clears up.

 

check the gasket between the turbo and manifold

 

2 front most bolts holding the manifold to the turbo. As mentioned above, check that gasket!

 

you might need a new gasket in general if tightening them doesn't help, or have you checked for cracks in your manifold? is it the factory log manifold or aftermarket?

 

aftermarket manifold. i tighted them a lil because some were loose.. still no difference. there was a hairline crack but i cant see that thats the problem because it ran fine before.

 

If there is a crack, you can check how badly its leaking by spraying soap water on the manifold.

Ideally do it cold, spray suspected area. Watch for bubbles. If there is any, that could be your problem. Any leak from the head to the downpipe will cause all sorts of weird boost issues. If it ran fine before, there is prob more than one issue.

 

yeah my old manifold had a huge crack you could feel exhaust come out of right around the weld where the collector meets the flange, needless to say my 6262 would still hit 30psi, but it sounded like a tractor, and didnt spool until 6500 instead of 4700.....

you experiencing excess lag at all OP?