[earl3]

Still troubleshooting some issues with my SP58GT BK:

The car is an auto and after each shift (WOT) boost will drop from 17 psi down to 12, accompanied by a hissing sound, and slowly regain back up to 17 psi.

The obvious answer is a boost leak however I have run a boost leak check to over 25 psi and nothing is leaking.

Is it possible that the dynamic pressure of an actual running/boosting engine is uncovering a leak that my static pressure leak tests are not finding?

Any ideas???

 

[Sound Performance]

trac fuse in or out?

 

[earl3]

fuse is out for now

 

[pepsitt]

i'm having the same problem but with stock twins. If I floor it in 3rd at around 50 mph or 3900 RPM, once it hit 4200 it would boost up to 1.21 and hold it there until around 6 where it would drop down to 1.1 by redline....once I shift into 4th, it would go up to 1.17-1.18 and then drop down to 1.1 at redline.

Some days when I floor it in 3rd at 3700 RPM, it would sustain boost of 1.25 all the way to redline when i end up shifting at redline and when i shift into 4th gear, it would be at 1.20 and continue to drop slowly.

Does anyone know whats causing this. Here is a little info. I'm 6 spd with the spring mod on my wastegate. BPU with intercooler. I'm in perm TTC. Any light to this matter is much appreciated. Thanks.

 

[Espeefan]

Blow off valve, maybe? Seems strange you pressure tested okay to 25 psi though. Something must be happening (changing) with the car actually running.

 

[earl3]

'twas a bad MBC, everything is fine now.

Thanks

 

[pepsitt]

do you guys think i have a bad boost controller? i have apexi avc-r. Could it be my stock wastegate?

 

[earl3]

do you guys think i have a bad boost controller? i have apexi avc-r. Could it be my stock wastegate?

your problem is actually opposite of mine and common on BPU supras -dropping boost in the upper rpms. Do a search for the spring mod.

 

[UAE Boost]

i'm having the same problem but with stock twins. If I floor it in 3rd at around 50 mph or 3900 RPM, once it hit 4200 it would boost up to 1.21 and hold it there until around 6 where it would drop down to 1.1 by redline....once I shift into 4th, it would go up to 1.17-1.18 and then drop down to 1.1 at redline.

definatley a week wastegate .
try to use a stiffer spring on your springmod or tighten it out , that shall fix it