boost fluctuation WOT,...WTF? (03 wrx)
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This is a discussion on boost fluctuation WOT,...WTF? (03 wrx) within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; as the title says, my boost fluctuates when i open the throttle 100%. it goes up and down from 16-10 ...

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    boost fluctuation WOT,...WTF? (03 wrx)

    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. 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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    +1. Just test drove an 04 with the same problem...

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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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    Master Baiter EJ257's Avatar
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    You have modifications beyond the specifications of Cobb's map.
    Last edited by EJ257; 11-10-2011 at 06:22 AM.
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    Registered User 06scoobyrex's Avatar
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    Quote Originally Posted by EJ257 View Post
    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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    http://www.clubwrx.net/forums/showth...57#post2688257

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    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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    Registered User teflon_jones's Avatar
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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.
    Scott
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    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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    Registered User teflon_jones's Avatar
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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?
    Scott
    Past Subies - '11 STI Limited stage 1+ and '04 STi stage 2+
    '13 Wrangler Rubicon - custom front bumper w/12k lb winch & off-road lights, skid plates, diff guards, etc.
    '04 Porsche 911 Turbo GT2 clone 600 HP/TQ
    '77 F-150 heavily modded for off-roading

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    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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    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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    Registered User teflon_jones's Avatar
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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...
    Scott
    Past Subies - '11 STI Limited stage 1+ and '04 STi stage 2+
    '13 Wrangler Rubicon - custom front bumper w/12k lb winch & off-road lights, skid plates, diff guards, etc.
    '04 Porsche 911 Turbo GT2 clone 600 HP/TQ
    '77 F-150 heavily modded for off-roading

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    what three questions?

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    Registered User teflon_jones's Avatar
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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?
    Scott
    Past Subies - '11 STI Limited stage 1+ and '04 STi stage 2+
    '13 Wrangler Rubicon - custom front bumper w/12k lb winch & off-road lights, skid plates, diff guards, etc.
    '04 Porsche 911 Turbo GT2 clone 600 HP/TQ
    '77 F-150 heavily modded for off-roading

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    Registered User GarrettKoonsman's Avatar
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    Pull motor and replace.

    /thread
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