Bizarre intermittent boost leak??

[Spoolin92GSX]

So, I've had this odd boost leak for a month or so now, and have not been able to track it down. It doesn't leak vacuum, only boost so the car idles fine. Basically, once in a while I'll get on it a little and it will spit/sputter and go very rich. Once it leaks I can snap the throttle shut and the leak stops. WTF Throttle body has been rebuilt, and BOV is recirculated so I don't think that would be the cause could it? Any help is appreciated, this is just too weird!

 

[007jimmy]

So why dont you do a boost leak test and fix it? You might find more then one..

 

[SleepingTSI]

The boost leak test should find it as he said above, but I've had this problem a few times when I put things back together in a hurry. Usually turned out to be one of the IC pipe connections wasn't tightened down so when you snap the throttle shut and it goes into vacuum it's almost like sucking the leak shut till you boost on it again and pushes it apart a little at a time till it's leaking again. I'd check all your connections and be sure they're in and clamped tight.

 

[Spoolin92GSX]

I should have clarified I've done several boost leak tests and it doesn't leak during the tests. When driving it will only leak maybe 3 or 4 times in a span of 50 miles, once I snap the throttle to stop it the leak is gone for probably an hour at least. I am fairly capable with these cars, but as everyone knows intermittent issues can be a pain to track down so I figured I would see what others have experienced. Thanks for the suggestions so far.

 

[bryanwheat]

IF it holds during a test than it likely isn't a boost leak that is causing your problem. I would test the tps sensor, and ignition system.

 

[Spoolin92GSX]

IF it holds during a test than it likely isn't a boost leak that is causing your problem. I would test the tps sensor, and ignition system.

That is a very good point.. TPS as many times as I've tested it has been good, and adjusted perfect. Ignition would make sense but I would have no idea where to begin testing given the behavior, I could see it being one or more cylinders not firing/firing wrong but how could snapping the throttle affect that? I really wish I could catch it on a log >_<

 

[And_44]

I had an issue that seemed like a boost leak and was solved in same way as you turned out to be phantom knock.

My knock was coming from a loose vacuum hose bracket on back on engine below intake manifold right next to knock sensor removed bracket and never had issue again.

 

[Spoolin92GSX]

Almost forgot about this thread, figure I should give an update. I FINALLY caught the little bastard on a log, and it is indeed phantom knock. Felt exactly like a moderate boost leak and looked like it on the boost gauge/wideband.

At least now I know where it's coming from, now to figure out how to STOP it

EDIT: Knock sensor is a few hundred miles old OEM Mitsu unit, ECU also a few hundred miles old after a full repair and socket from ECMTuning.

 

[96talontso]

Just re-read this. Nvm

 

[Spoolin92GSX]

Just re-read this. Nvm

Huh?
EDIT: Got the email for your post , I had that issue a while ago and fixed it with non-protruded 7's Thanks for taking the time to respond though, I'm thinking (hoping) the KS just worked itself loose somehow.