Evryone comlains of boost creep, i got boost fade, i start out with a small spike to about 24 psi, then drops to 23 and holds there till 5500 rpm then drops off drastically.down to 12 psi usually.would a restriction in the exhaust cause this? turbo clipped too much?too much timing advance?
im thinking the flex pipe is coming apart inside.
see sig for mods... along with the rest of the obvious stuff.

 

Do you have an external or internal wastegate? Is it stock or is it a 17psi aftermarket internal?

 

I have a stock internal wastegate im thinking it boosts 10 psi without a BC inline? i dont really remember i never ran it but one time without it.forcing the WG open maybe at higher RPM? i'm not a big fan of external wastegates. the internal is whatever setup was on it when i got it.

 

i just thought maybe i have the coarse adjustment on my MBC too tight, the fine adjustment is only backed out1 turn, i know all the way in the WG will just get stuck open cuz it wont bleed off the pressure from the actuator and it will never go back shut. i'll try starting over with that and see what happens.

 

Yeah, I asked about the wastegate because of that 10psi actuator...with a 20G! lol. That's a lot of air, even with a BC inline. Maybe the BC is leaking, it does have a pinhole to bleed out of. Just a thought.
I'm beginning to sway away from the actuator, 10psi actuators are usually put on from Hahn and the likes, unless the buyer asks for a 17psi one, but it doesn't matter that much (only assurance), as long as there's a BC inline from the actuator and compressor housing and not the bov.

 

stock fuel pump?

 

The boost controller does bleed off but i thoughtmaybe not enough. its a turboxs 0-30 psi so i figured it would work decent. i readjusted the coarse and have the fine almost all the way out to make it 20 psi for now it bleeds the actuator shut alot faster this waybut still drops off the same. 12 psi by 5500-6,000 rpm. If i retard the timing 2 degrees the boost stays up a little better but still falls off. i decided to try it once with the hose pulled off the actuator, i brought it up to 5,000 RPM, then went WOT and i got about 12-13 psi. so i tied the wastegate shut and went for the same sort of run - same result. maybe im missing a leaking exhaust gasket before the turbo? i just rebuilt this one and its in really good shape it just had a leaky oil seal. its ported and clipped, but not clipped much at all, very minimal. and it was rebalanced.I have to be missing something simple. If the wastegate leaked that bad when closed i dont think it would ever make it to 25 psi in the first place and i cant hear the turbo slow down or fade off. Im beginning to wonder if i didnt acidentally put the wrong turbine on it or somethin having 4 turbos torn apart here[&:]Maybe i should go through all of my parts again to see whats not put together. I'm gonna go put a 2nd guage right at the turbo outlet , maybe i have a restriction in the intake side thats not allowing enough volume to make it to the engine.

 

Ok so the 20g comes off, i find a new turbine and the big 16g is back on.[:'(]something went through the turbine and trashed it.appears to be a piece of cast iron that flaked off the manifold near a crack so i ****canned it and put my el cheapo pace setter tube header back on that had a hole burnt through it.
( of course i welded a patch over the hole)

 

Oh wow. Did you just get that turbo or rebuilt it too? That just sucks!

 

I just got it with a box of parts from a GSX and galant that someone had no clue what the stuff was, it was in great shape but i put oil pressure to it and the seals leaked & had some shaft play, so i just put bearings & seals in and had it rebalanced while it was apart. That does suck because a turbo isnt the quickest thing to change on a car. i Also just put the water oil cooler back on, i had the 90 filter deal on there with no external cooler and had an oil temp of 280 degrees, thats really bad too. I'm surprised i never heard it make any noise being that torn up, if my digital cam worked i'd have pics already. it looks like you dropped a 1/4" bolt through it at WOT