exhaust valve actuator

[tez n u]

Tried to adjust the exhaust valve to reduce vod....made a difference but car started to overboost and hit boost cut. Now did i loosen it up too much or is there something else goin on? Tighten it back up and no more boost cutt but cars gone slower again

[B4_685]

...I\'d be a bit sheepish messing with the wastegate adjustment if I were you, but that\'s just me - risk over-speeding your turbo which will eventually cause irreversible turbine damage as it will be pushing it beyond its design rpm/limits. What boost are you getting with it in the normal setting? Any smoke? What are you driving?

[tez n u]

Its a 98 bg5 gtb an its not the wastegate actuator im talking about i was trying to adjust the exhaust valve actuator on the secondary turbo to try an reduce VOD.

[B4_685]

Ahh my bad have you done the BBOD clean up? Any CEL codes?

***Edit***

Hose 10 mod/after market BOV or stock?

[tez n u]

Bov is still stock, car just has fujitsubo axle back exhaust system so still has both cats

[Marky]

Seems weird

ECV should have nothing to do with how much boost it runs unless its not closing properly - but that will only effect primary boost as it\'s stuck halfway switched

how much boost are you actually seeing on both single & twin? to hit the actualy "boost cut" youve got to be running some wicked boost, prob is likely something different altogether

to "adjust" it to the sweet spot, you wind it quite far out so when its idling it sounds monotone, then wind it in (in a hurry as you\'ll burn your hand eventually) to the point where you hear the exhaust note just start to change - the flapper will rattle as it\'s juuuust getting seated - then go a turn or so past that. Means it\'s basically right on the verge of opening so you will find a bit less boost around 3-4k as it pre-spools, but it gives it the longest "reach" it can have via adjustment - means shorter VOD and most gas possible when on secondary so it "should" make more up top

if you want to hold more midrange you wind it closer in, means VOD slightly more pronounced as turbo gets less pre-spool but it holds more flow to the primary between 3-4k

[B4_685]

 Marky said:

how much boost are you actually seeing on both single & twin? to hit the actualy "boost cut" youve got to be running some wicked boost, prob is likely something different altogether

Any idea what level boost got to before it went into fail safe mode? (Boost control via BOV bypass I assume - or is it fuel/ignition cut?)

Link to Twin Turbo information PDF:

https://docs.google.com/file/d/0B1WNPjT7ZI3QYUpic3NpQ0s1NU0/edit?usp=sharing

[tez n u]

After adjusting it i took it for a drive and it felt like i hit a brick wall, rev fell to zero and then it started driving normal until i booted it and secondary kicked in and hello brick wall again.....when i put the actuator rod back to normal the brick wall symtom went away car doesnt have a boost gauge (just got car couple of days ago)

[Marky]

My understanding is its load based not a specific psi number so it varies a bit, but plenty of folks seeing 20psi plus with no cuts

There should be though haha its 95% the reason these things blow up so much, just let the factory control it bro its sweet oh what\'s that nunga nunga noise it makes now

Cut is an ignition cut as primary bov is pneumatic only and secondary will only bleed when in tt mode

I\'d say get a gauge on it before fiddling they have been known to do some weird shiza (see above re nunga nunga haha)

[B4_685]

Lol @ nunga nunga

[lachlan]

Is nunga nunga the noise it makes as it eats a bearing but before kablam the piston makes hitting the head ?

[Marky]

Ha, yes. Not to be confused with tinka plink tink the sound of your Subaru dieseling its way to an early grave

Or clonka clonka piston slap "nah that\'s just cause they\'re semi forged" cold ej20 either

Its hard to type sounds

[tez n u]

Did a few 3rd gear pulls today to see what the afr is using wide band, found out its running pretty rich 10.7:1 on boost even when secondary comes on.