ST185 Boosts 12psi then down to 5psi

[FSRRM]

Hey guys,

I will keep it simple here

Car: ST185 Celica GT4
* Stock exhaust with big bore
* Pod Filter
* Cheap Boost Tap

Raised the boost to 12psi and blocked the VSV system.

I'm hitting 12psi then it will drop all the way down to 5psi in a matter of seconds.

2nd gear pull ~foot to floor~ 10~13psi then slap 3rd nicely and quickly 7~5psi constant... WHAT IS UP?

[MilfHunter]

Im no expert but I had a similar experience with a ST165 I bought.
The previous guy added a boost gauge and at 12psi it leaked at the T/B and lost all pressure.
Check all your connections and pipes.
Spray the pipes with soapy water and rev it up, you should see bubbles where there are any leaks.

[Al]

Boost leak somewhere.

[Grrrrrrr!]

Wastegate or bypass valve sticking open? Stock exhaust... so no China China down pipe?

[FSRRM]

Very true, I might have a boost leak, although I thought if I had a boost leak it would boost more?

[sergei]

Very true, I might have a boost leak, although I thought if I had a boost leak it would boost more?

nope.

Do you have BOV? perhaps that is leaking?

Check for loose clamps....

[FSRRM]

Very true, I might have a boost leak, although I thought if I had a boost leak it would boost more?

nope.

Do you have BOV? perhaps that is leaking?

Check for loose clamps....

I do! It's a cheap knock off too. So I am wondering if i should silicone the nipple up as it came loose when tried to take the vacuum off