Crazy boost spiking and jumping!!
 

So I am driving my car today and I notoce that it's jerking kind of bad. So I monitor the turbo guage for a little while and I notice that the boost is jumping from 15 down o 10 and back up to 15.. It's doing this very fast and the car is reacting to it. I tried resetting the ecu but that didn't help. I have a feeling it's a vacuum line but I have my doubts for various reasons.

I have a few mods in the car including an STi uppipe, removed silencer, kn filter, and an aftermarket turbo guage.

Does anyone have any ideas as to what it may be?

Thanks in advance

Rus

anyone??

So here's some more info.. When the engine is a bit cooler, like when I get in after not driving for a little while, the turbo is laggy and won't climb past like 10 psi. Then when it heats up it starts going crazy. Also, if I let the turbo climb gradually, it doesn't spike crazy.. it kind of balances out. When I stomp on the gas, the turbo climbs super quick and then once past 10 psi starts going crazy. Also, the idle pressure is lower than usual, it is at about -25 psi. It used to be at like -20 psi.

Maybe I have a boost leak somewhere? Or is it vaccum lines? Or is it someting wrong with the wastegate? Those are the only things I can think of.

so no one knows? no one has any ideas?

Check for boost/vacuum line leaks. If you have a buddy with the same car, try swapping boost solenoids. Maybe your's is borked.

Spiking
 

I have a similar problem w/ my 02 wagon that was protuned by TDC. Jon told me that it was the ECU trying to make target, overshooting, the correcting. He said it was a simple cure. Jerry, at Deadbolt suggested that the pill i.d. might need to be a little larger. I have one of the infamous Momentum 40T's, and it has been suggested that the hot side need's to be ported.
This only happens during accelleration at slightly less than WFO!

What other mods do you have except up-pipe?

well, I have a boost guage and an axle back. I checked the link at the boost guage and it seems fine. I also have a k&n, and i cut out the silencer. I have a few suspension mods (that are making my right side click all the time).

it kind of went away now but it seems like the vacuum is way to low now at idle... it's reading at like -25 when I am cruising and not pushing any gas... I'm not sure but I thikn it used to be somewhere around -20.