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Boost Issues....flat Spot In High Rpms

steven13

By steven13,
in Engines & Forced Induction

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steven13 Apprentice

steven13

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Ok today i finally got my new GReddy Profec B II boost controller... and it has been installed as per instructions... but we are having a few issues...

Now previously i had a Turbosmart Boost controller which was only giving 10psi and we couldnt get anymore then that from it...

After installing it.. we started driving it around back streets and pulled 11psi in 1st and 14psi in 2nd.... which is great as really goes much better now...

Now heres the problem.... in 3rd...4th and 5th gear... it starts to hit boost at 3200rpm... but as soon as it hits 3900rpm... the boost disappears... We tried this a couple of times and eventually found that always at 3900rpmish it will disappear then reappear at 4600rpm... like a BIG DEAD SPOT.

This onyl happens in 3rd 4th 5th gears... not 2nd or 1st as these are perfect... So my question is... has anyone encountered this problem before...

Could it possibly be that the wastegate is shutting on me for some reason at a certain rpm.... ... Also.. it never happened on the previous boost controller.... though it never had more then 10psi.... But when i dont spool over 9psi it seems to work fine....(i think)

Any solutions to maybe keeping the wastegate open if it is shutting??

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https://www.sau.com.au/forums/topic/174309-boost-issuesflat-spot-in-high-rpms/
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