Boost Spiking problem

[jl_audio_666]

I have a 97 GS-T and it is pretty much stock other than a injen intake a 2 1/2 exaust from header back. I just recently had a boost controller and and I got rid of it because i thought it was making my boost spike. When i removed the boost controller i put ever thing back to the way it was stock but i didnt know what size vaccum lines to use. Everything is off the boost controller now and it is stock. My car is only vaccuming at about 16in hg at idle at 800rpm and my boost climbs to about 13-14. Once you get to 5000 rpm's it drops to about 10-11. What could be my problem? can anyone tell me i need to get to re-pipe all the lines to normal?

 

[munguiaoh]

I have a 97 GS-T and it is pretty much stock other than a injen intake a 2 1/2 exaust from header back. I just recently had a boost controller and and I got rid of it because i thought it was making my boost spike. When i removed the boost controller i put ever thing back to the way it was stock but i didnt know what size vaccum lines to use. Everything is off the boost controller now and it is stock. My car is only vaccuming at about 16in hg at idle at 800rpm and my boost climbs to about 13-14. Once you get to 5000 rpm's it drops to about 10-11. What could be my problem? can anyone tell me i need to get to re-pipe all the lines to normal?

first check to see if the turbo vacuum lines do not have any leaks, i would replace them. if you can get a ported, or port out your o2 housing.

 

[oldman]

Once you get to 5000 rpm's it drops to about 10-11. What could be my problem? can anyone tell me i need to get to re-pipe all the lines to normal?

This is normal for 2G's mostly due to two things, mostly.

1. Leaky 2G plastic BOV.

2. T25 dropping off at higher rpms.

-16in HG at idle is also an indication that you have leaks, perform a boost leak test and fix them.

 

[Eastwood95]

The wiseman has spoken........
T25=boost dropoff after 5k rpm
Why did you put everything back to stock? Are you still using the stock Boost Control Solenoid?

 

[jl_audio_666]

Im putting everthing back to stock because it's almost winter in wisconsin and that car has a little to much power when the boost controller is hooked up so i'm taking it out for winter but it's going back in...I also have a APEXi S-AFC and HKS SSQV POV and i have replaced all the vaccum hoses. Is the T-25 just known to drop down when you get to 5k...it also sputters once and a while when i give it like 20-30% around 2k-3.5k rpm's. What could be the cause of that?