snub disphenoid

My boost pattern right now is ~10-5-10. Sometimes in first gear, it won't pop up to 10psi until ~6800rpm. It dips down to 5psi around 4000rpm, then around 5000rpm the boost gauge needle goes a little crazy. The higher the gear I go into, the less time it spends hovering around 5psi.

Yes, I searched. Yes, I checked all of my vaccum lines. I installed an Efini Y-pipe today and while the Y-pipe was off i inspected all of the actuator on the y-pipe. The actuator was quite sticky, so I cleaned it and lubed it a bit. I think it helped the situation a little bit, because I can hear the car losing traction a bit in first gear, but the boost gauge needle still does its little dance between 4000-5000rpm or so.

I imagine it couldn't be the catalytic convertor, it's a fairly fresh high flow unit, and I imagine a clogged cat would just create an exhaust restriction that would lower the boost in general, not just in the middle of the boost pattern.

Any suggestions help, guys. I need to get this thing ready for the dyno for Sunday, and I've got everything else ready, but this little problem still persists and it's getting annoying.

kashent

Your secondary turbo precontrol isn't working. There's a few things it could be:

1) The actuator (which I presume is what you checked) - it's the lower one under your front turbo

2) The Precontrol Solenoid - screwed on to the front of your UIM, there's two solenoids. It's the one to the passenger side of the car. You can unscrew them from your UIM, unplug the connectors, ease the two vacuum hoses off the bottom, and tap it with 12 volts to see if it clicks. If it does, it works.

3) The vacuum lines to the Solenoid - check and/or replace the two lines that you popped off in step two. They're not too hard to get to and are pretty short. The rest of the lines should likely be okay since they're not exposed to as much heat. If that doesn't fix it, pull up the vacuum diagram, trace the lines that go to that solenoid, and start replacing.

Good luck.