Boost issue... having trouble diagnosing... Help?

[MeanGreenS13]

ok, my car has been seemingly SPIKING boost at around 14-15psi and droping to 10psi. I did a boost leak test and the one boost leak i did find and fix, didnt help this problem. I have a pretty much BRAND NEW hks gate on a stock T25 thats in very good condition, very little shaft play. ive gone through everything once or twice and i just cant seem to find the problem. I do not have an MBC or EBC on the car at the time and i would like to go to 14psi steady. From how i have the arm adjusted on the gate, i should be right at 14psi but im not.... any help is appreciated

Phil

[srpowered240sx]

check the vacum hose going to the gate. could be a bad seal on the hose to the nipple. change the hose, for peace of mind. my roomates crx did blew that hose off and overboosted his si motor and threw a few rods through the side of the block, so be careful overboosting.

[MeanGreenS13]

when i turn the boost up via MBC i just installed, it stayes at 14psi even, but when i put it at 10, it still spikes lol ill check some more things, thanks

[fiznat]

Based on your sig I assume this is a SR? Moving to the SR forum...

Edited your title, too.

[MeanGreenS13]

man i put this in GENERAL so that everyone would see it.. no offence to you admins, but sometimes, ASK before you move things please, now i bet no one else answers.

[karmakaze]

getting an attitude isn't going to get any help either.

[MeanGreenS13]

i just think ive been here long enough to know where things go, and if i dont put it there... its for a reason... i needed immediate answers, not an answer in 3 days

[climaxsr20]

i heard that t25 will go 14 psi but will drop down to 10 or 12 psi when your motor is at high rpm. might be because of the small turbine. sorry to say but your best bet is to leave it at 12 to be consistant.

[karmakaze]

i heard that t25 will go 14 psi but will drop down to 10 or 12 psi when your motor is at high rpm. might be because of the small turbine. sorry to say but your best bet is to leave it at 12 to be consistant.

your problem stems from the physical limitations of your turbo. want to go higher? you will have to upgrade your turbo. above 12psi the t25 starts to loose efficency.

[MeanGreenS13]

ive got friends in town running 14psi steady all day long on their t25... i dont think its a matter of the turbos efficency... ive gotten it to hold at 15psi already... i just cant figure out what has suddenly changed. all vaccuum line is BRAND new as of 2 weeks ago and hasnt been touched since. and the problem just arose 4 days ago or so

[DrifterProdigy85]

sounds like the HKS Wastegate is set too tight causing it to always boost to 15psi. The T25 physically cant flow enough air to hold 15psi to redline. Its always gonna drop to 10psi around 5500+rpm.

[BaliLover]

Shaft play isn't the only thing that causes a turbo to not hold higher boost levels. There are seals that can and most of the time do begin to leak. Almost every T25 SR I've ever driven would do a max spike of 14-15psi then drop back to 10-11. This is with both MBCs and EBC.

[Nismo_Freak]

No SR T25 is going to hold 15 PSI to 7200, you are lucky if it holds 10 PSI to 7200.

[Nismo_Freak]

man i put this in GENERAL so that everyone would see it.. no offence to you admins, but sometimes, ASK before you move things please, now i bet no one else answers.

It's an SR specific question and it belongs in the SR forum.

Don't ask for help then try to tell us how to do our job.

[Nismo_Freak]

i just think ive been here long enough to know where things go, and if i dont put it there... its for a reason... i needed immediate answers, not an answer in 3 days

Evidently not, you are still a noobie chief.

You didn't need an immediate answer, you are just impatient.

[MeanGreenS13]

boostin issue could apply to RB, KA, CA, VG, or SR... i did not specify, because i know there are people from EVERY corner of boosted nissans that could possibly give me an answer. and thats my answer to you, as for the boost problem, i got it fixed by putting a stock gate back on and turning up the MBC to 14. it holds there strong and steady most of the way. and drops off to 12 at about 7500rpm but thats it. my previous problem was it would spike at 15 to 17psi around 3500rpm and be at 8-10psi by 4000rpm. please lock this thread and thanks for the help for those of you who offered it

[Nismo_Freak]

boostin issue could apply to RB, KA, CA, VG, or SR... i did not specify, because i know there are people from EVERY corner of boosted nissans that could possibly give me an answer. and thats my answer to you, as for the boost problem, i got it fixed by putting a stock gate back on and turning up the MBC to 14. it holds there strong and steady most of the way. and drops off to 12 at about 7500rpm but thats it. my previous problem was it would spike at 15 to 17psi around 3500rpm and be at 8-10psi by 4000rpm. please lock this thread and thanks for the help for those of you who offered it

You have an attitude problem.

The problem could have been SR specific, and you obviously failed to correctly address others of your problem as the story has now changed.