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Discussion Starter #1
as the title says, my boost fluctuates when i open the throttle 100%. it goes up and down from 16-10 psi. i have a new wastegate solenoid, new wastegate, new bypass valve (blow off valve), replaced the upper and lower intake gaskets, i do have the right size pill on the compressor side vacum hose before the t-fitting, all the vacuum hoses are new and are in the right place. i have even replaced the upipe, down pipe and installed equall length headers along with a cat-back exhaust. iv also added the cobb intake, perring turbo inlet, and have it set on stage 2 93 on the cobb access tuner and still the damn thing wont stop fluctuating:confused:. if anyone really knows whats up, let me know what im missing. and dont tell me the vaccum hoses are not right and dont send me the picture of cobbs "how subaru boost system works" iv seen it a million times, the vacuum hoses are fine and i do not have a boost leak because it boost past 19psi and will not fluctuate with a manual boost controller. Please help!!!!!
 

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I've read several things in regards to this problem (had a similar issue), one post said the wastegate actuator lever needed to be adjusted one to two rotations tighter...

I just did oil change and new plugs and aside from one initial bounce (more of over boost spool) I have no boost pulse issues as I did after installing my AOS....
 

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You have modifications beyond the specifications of Cobb's map.
 

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You have modifications beyond the specifications of Cobb's map.
THIS^^^

Throwing a bunch of parts at a boost osculation issue doesn't make sense... Your lack of tuning for the extra parts that are normally frowned upon ISN'T going to solve your problem just give you a bigger headache...
 

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Discussion Starter #6
wow, i hate to say but thats about the sh***est advise iv ever gotten? my mods are frowed upon?? and i have too many mods on my car for the cobb access port after they told me that all the mods i have done are fine?????..........next......
 

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Don't ask for advice and get the right answer and then be a jerk to people that are trying to help you.

You don't have a map that supports your mods. It's as simple as that.
 

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Discussion Starter #8
really? what mods that i have done are not suitable for the cobb stage 2? i replaced the bypass valve, wastegate, wastegate solenoid, and intake manifold gaskets with stock "from the dealer" subaru parts. cobb stage 2 requires cobb intake, and the exhaust that i have done, the only thing that might be different is the turbo inlet but i spoke with cobb technical support and they said this mod is fine for stage 2. and if you read my first post, you would know this problem was happening before all of this was done. no, its not that simple
 

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In your first post you indicated you have a BOV. Do you have one or do you have a stock BPV? I'm also confused why you replaced all of the parts you listed. Were the ones on the car not working? Why did you replace the intake manifold gaskets? Were you just trying to fix the boost fluctuation issue? You also mentioned a MBC. Do you have one on the car?

While Cobb support may have said the turbo inlet was ok, their map notes clearly state it is not. You also have equal length headers, again not supported by the map you're running. The fact that the issue existed before you installed them is a red herring. You introduced a new variable into the equation that may be causing problems, but there's no way to know because the car was already running badly before the change. In order to troubleshoot the issue now, you need to be running a tune that is correct for the mods on the car. Put the stock headers back on and the stock inlet to start with.

How many miles are on the car? When did this first start happening, and what was the setup of the car at the time? Have you gotten any CELs?
 

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Discussion Starter #10
the problem i have now is the same problem i had before i did any of the parts,mods, or tuning (the car was bone stock with same problem). the bypass valve, wastegate actuator, wastegate, and intake gaskets are all new stock parts (not after market) the mods such as intake, turbo inlet, headers, upipe, and catback exhaust are aftermarket. after adding these stock parts, aftermarket mods and tuning with cobb, it ran much better, very responsive, and definetly faster. but it still has a boost fluctuating problem. so nothing i have done has caused the problem, only made things better, meaning the fluctuation isnt as aggressive as it was, but still present.
 

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Discussion Starter #11
im using the stock bpv. i used a mbc just to see if it would hold steady boost and it did. when i take the mbc off and let the computer control the boost, it fluctuates. yes, i was trying to fix the issue by proccess of illimintaion. i do not want to use a mbc.
 

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You didn't answer any of the last 3 questions I posted and I can't help you until you do...
 

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How many miles are on the car? When did this first start happening, and what was the setup of the car at the time? Have you gotten any CELs?
 

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Discussion Starter #16
i bought the car with 116k, it now has 130k. it has always fluctuated since iv got it. no cels or dtcs. i have a snap on moddis 2 scan tool and it passed all test.

garrett, engine is in great running condition, no taps, no knocks, no leaks, great compression. why would i replace it?
 

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Discussion Starter #18
that would make sense,...but wouldnt the reflash from the cobb access tuner fix that? it re-maps the wategate duty and boost targets
 

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Garrett's post is probably because you weren't paying attention to questions people asked (like me) and posting the same thing over and over again...

You've kind of done that again where scoobyrex has given you the next steps to figure out your problem, you say it makes sense, yet question the answer again.

Take it to a tuner for datalogging. You've had these problems since you got it, so there's no way to know what might be causing them in the absence of any codes or blatant red flags.

While Cobb support may have said the turbo inlet was ok, their map notes clearly state it is not. You also have equal length headers, again not supported by the map you're running. The fact that the issue existed before you installed them is a red herring. You introduced a new variable into the equation that may be causing problems, but there's no way to know because the car was already running badly before the change. In order to troubleshoot the issue now, you need to be running a tune that is correct for the mods on the car. Put the stock headers back on and the stock inlet to start with.
Did you read this?
 
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