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I just bought my 04' Forester with the standard STI stage 2 upgrades. VF43 Turbo etc..

When I put the pedal to the metal I can feel the boost kick in, hear the throaty roar then it cuts back and so does the power as I accelerate.

If I floor it while in 6th gear, the boost fades in and out as I accelerate.

If I put the pedal down 2/3 to 3/4 it doesn't fluctuate but doesn't accelerate as fast.

Only thing that doesn't match the mod package is that it has the stock intake. I am going to replace it with a AEM soon.

SOO...

Is this a tune issue or is it a hardware issue? Do I need a new wastegate manager? or is it the ECU improperly controlling the engine.

Thanks for the Help!!:icon_biggrin:
 

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06 Fxt
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89 Posts
my 06 fxt does that since i added a pod intake.. my best guess it its spooling faster than expected due to the added airflow, and its overcompensating back and forth resulting in the boost surge .. i'll let someone more educated say for sure but i've heard tuning can fix this
 

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2004 Subaru FXT MT
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1,853 Posts
It all comes down to improper boost management...

Could be surging as well. If you are WOTing it in 6th, either you are badly abusing the speed limit or you are at low rpm, which is pushing the turbo into a high boost, low flow region, which pushes it over the surge line...
 

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2004 Subaru FXT MT
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Only thing that doesn't match the mod package is that it has the stock intake. I am going to replace it with a AEM soon.
If its a short ram that you are getting, I swear I'll stop responding to your posts (maybe that is a good thing to you...lol)

It better be a CAI version....

At any rate, you choice of intake won't change tune or whatever is causing your issues. Don't misunderstand, you will see half the pressure drop, but an intake doesn't cure boost control.
 
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