bcope

Under full throttle the inlet hose at the intake manifold is blowing off with a loud (almost backfire like sound)and car lurches to a crawl. No ECM lights showing. Thiniking possible N75 and overboost situation here (have not noted a runaway boost issue on boost gauge however). Disconnecting N75 and running car to 6 lbs at full throttle seems fine. Thoughts?

Flyboy

Try and attach the throttle body boot better. That's not a part to commonly pop off even with significantly higher than stock boost levels. Alternatively you could install the APR bipipe which bolts to the intake manifold and would never have a problem with popping off.

bcope

Thank you,

We tried to resecure the Y pipe and changed the N75 Valve. No overboost noted (around 13 lbs with current tune), but shifting from 3rd. to 4th. at full throttle the Y pipe blew off again and caused a traction control light and an ECS light. Both went away shortly after reconnecting the Y pipe and driving at low presure levels

We pulled off the Y pipe and cleaned out the oil residue inside and around the area where it attches to the intake. The N710's are relativley new, but what prevents over presure at instake when throttle is released rapidly, the wastegates? We are going to go for another full throttle run later today.

bcope

Okay, so after cleaning the the inside of the Y pipe clean of all oil and reclamping it and changing the N75 valve all seemed fine. Pulling strong with no issues through 16 Lbs boots at 3/4+ throttle. Pushed it to full throttle in 3rd and it overboosted to 20+ LBS and went into limp or shut down with nock sensor or other, not sure(no dash lights though). Thoght we had rulled out leaking vacuum lines by running N75 unplugged and getting 6-7 Lbs. at full throttle.. Any ideas what to look for now?

Flyboy

Are you able to log the car? Plugging in the N75 seems to be related to the over boost.

The y-pipe is the hard pipe that sits on top the intake manifold, it never sees boost. I think you are calling the throttle body boot the y-pipe.