Weird Boost

[TSiWarrior]

When im idle, the car is at about -20 on my aftermarket boost gauge, when I hit the gas it initally goes down to about -30 then to about -10 then it comes back down to -20 even though im holding the gas steady, if i rev the engine to peak it will go to about 20psi then come back down to maybe 5psi and stay there even if I hold the throttle out, sometimes it will even go back into the negatives. I can hear the bov during shifts some time but it doesnt seem like it's keeping the boost. I've got a BIG 16g turbo. It's my first turbo so im not shure if that's normal, but I would think that the more gas you give the more boost untill it decides to dump. Anyone know what this is?

 

[marcmsj]

try swapping out your gauge, maybe yours is bad.

 

[realhp=turbo]

Your car does not create boost in neutral. It will come up to somewhere around 0 but thats it and its normal. Its designed to build boost when loaded. Some autos build boost in neutral because they have a constant load ie; the torque converter. But they dont build and hold that much in neutral.
mike

 

[oldman]

I highly doubt you can build 20 psi by free revving it, I would check the gauge first.

 

[TSiWarrior]

I just went outside warmed it up and here was my readings. (on BIG 16g, 2.5" exaust, 550 injectors, external dump)

idle -20
1k -30
2k 0
3k 1-2psi
4k 5psi
5k 8psi
6k 12psi
7k 18psi
PSSSST

Thoes readings are super weird... could they be caused by a vaccume leak or something? what kind of line is supposed to be used for the guage? I bought the car and it has a whitish hard plastic one, the inside diamater looks to be 5mm or so.

 

[Rick4g63]

The boost gauge is the likely suspect.
Check where the boost gauge line is connect toa good boost source.

 

[oldman]

The boost gauge is the likely suspect.
Check where the boost gauge line is connect toa good boost source.

I agreed except the PSSST part which sound like blow off.

 

[moliver]

Is your BOV vented to atmosphere?

 

[TSiWarrior]

The PSSST sound is the BOV. On a working guage, what should my readings be per rpm? or at least an estimate?

 

[TSiWarrior]

Is your BOV vented to atmosphere?

Nope =/ I want it to be but it isnt. Although when it goes off and the hood is open the sound is still earsplitting loud.