Hi, my 95 talon esi is going turbo and I installed a 13g, fuel pump, fmu etc.. I took the engine out to install the turbo and repaint the engine and engine bay. My turbo setup is ready except one thing, I did not pipe it to the intake. I wanted to test the engine prior to boost it.
Here comes my problem, the engine seems to run fine on on neutral, idle is fine etc.. Vaccuum is ok too.
But when the engine is under load...I hear a pssssss sound as soon as I open throttle, maybe it is the turbo but I was not expecting it to be as loud...the noise intensity do not change with rpm but the more I open throttle, the louder it is. And there is also a big loss of performance, I don't even reach the redline on first gear! Low rpm torque seems to be ok but as the rpm raise, power decrease.
I get intermittent Check engine for upper o2 sensor (now located in the o2 housing)but my problem is present regardless my CEL is on or off.
I will check for fuel pressure... I have to get a gauge.

Is the exhaust restriction caused by the turbo can cause a performance loss like this??

I hope someone can help me with this! Thanks!

OH yeah, your engine is using that energy to spin the turbine, but not getting anything in return from the compressor side. That's why even a small boost leak on a complete setup can have drastic negative effects, let alone not even having the pipes on. Your best bet is to just hook up the pipes, and set your boost as low as possible at first (2-5 usually is okay, if you can lodge your w/g open that'll do, but not likely).