Blew off a vaccum nipple!!

[boostjunkie]

I was trying to test fit a wrx turbo heat shield yesterday and noticed that a vaccum attachment on the turbo was completely open!! I don't know how long the vaccum nipple has been off the turbo but when I plugged up the hole with another nipple it made one helluva difference! Off boost acceleration increased dramatically, however, I'm getting the same extra-accleration letting off the gas . . . like the engine's adding more fuel to compensate for a slow reacting BOV . . .

Kinda weird that I was driving around for a while leaking boost to the atmosphere!!

[IggDawg]

you might want to get a small hose clamp to make sure she stays on. and watch out for that compressor surge. that has "teh bad". fix ASAP. I was getting that when I did the "vacuum re-route" thing and was letting the boost controller read from the manifold instead of the turbo. not good. I'm pretty sure I even got backspin a couple times.

-IggDawg

[boostjunkie]

Interesting. I checked my vaccum lines from the boost controller and noticed that it's tied into the manifold as well. I guess I should reroute the boost controller to the turbo vaccum attachment, huh?

DLC's install instructions for the Hallman boost controller say to have it rigged to the manifold. I don't think he had any problems with surging.

[vrg3]

If your boost controller is connected to the manifold, you end up allowing the compressor outlet pressure to exceed full boost, and get the full-boost-at-part-throttle problem. We've talked about this a lot in threads about FBPT and in threads about the "vacuum bypass" mod.

[boostjunkie]

But what I want to know is why I never had this problem before . . .

I know the connections for the boost controller haven't been changed since I got the car and the nipple was definitely on the car at least a month ago.

[IggDawg]

The nipple may have been off for longer than you know. It should be able to bleed off excess pressure. this is good and bad.

good: between shifts or whenever the throttle closes, that bleed point acts as a vent-to-atmosphere BOV preventing compressor surge. the bad thing

bad: -when your engine was pulling vacuum, I assume it would pull unfiltered air through that point. it's past the turbo, so at least there shouldn't be any damage to that. you may want to take take off your IC and check out its insides and the throttle body. between all the oil goop from the 1.32 million oil vapor recirc valves we have on our engines and the unfiltered air, you may have some sludge in your system.

-also, that will releive a lot of pressure from the system. if you're reasing 16.9 PSI at the manifold, your turbo may be working hard enough to blow ~23 PSI at the turbo, since you're bleeding off pounds at that nipple. If you were still on the stock turbo, I think your turbo would be in trouble. the TD05 should be able to handle that no problem tho.

my suggested remedy: immediate oil change and another one very soon. this is on the assumption that you've been pulling unfiltered air through that fitting. also, I'd suggest rerouting the boost controller to read from that fitting. leave your boost gauge at the manifold tho. that's where it should be reading from IIRC. you want to be seeing what your MAP is seeing.

I could be wrong on some of this, but it's my best guess.