BOV flutter at part throttle... and tuning

[Omega]

FYI: Logger is in the mail.

New turbo, piping, Greddy BOV, exhaust.. blah, blah.

I initialy had the BOV set WAY to tight. It would vent and then the car would fall on its' face (I assume the turbine was getting hit with back flowing air). With a little off-the-cuff tuning and lossening the BOV that has fixed.

Now at part throttle at ~13PSI I can hear the BOV fluttering. I am not sure if the tuning is off or the BOV needs to be tighter. I would think that if the BOV was too loose, it would just go back into the intake and that would be the end of it. That is why I think my AFC settings are way off.

I haven't run the car that much. The settings at the moment are -3 accross the board but +5 at WOT. It feels pretty good, but the top end is lacking.

Anyone have any input? I'll post a log over the weekend for better analysis.

 

[candela]

i know Im not really supposed to do this but use the damn search man! This topic has been covered more extensively than anything else on this entire board!! And there hae been at leist 5 detailed ones in the last month that can EASILY be found by SEARCHING!!!!!

PS-please dont erase me...this needs to be seen by others so they know!

 

[LandoAWD]

I agree that searching will help. How do you know to set your AFC as such...seat of the pants/butt dyno? FWIW, your BOV will not affect AFC settings unless you have a massive leak.

 

[thehyena]

i think you should just tighten,test and repeat until you get the desired results.

 

[kpt4321]

The Greddy BOV has a boost-reference port like most BOV's, right?

If this is the case: At part throttle, the boost from the boost reference port (pre-TB) will force the BOV to open slightly, due to the manifold having less pressure than the upper IC pipe.

 

[Omega]

I have been reading about "how to" adjust the AFC for weeks now, here and other boards. My question wasn't "what should it be set to, or how to adjust the BOV". I would like to know if improper tuning of the AFC could cause the BOV to flutter... I have read nothing about that.

In my eyes the BOV shouldn't flutter unless I close the TB.. which I am not. Could I be on the margin of it being too loose and it releiving just some of the pressure is enough for it to close, and then the cycle starts over again.

 

[echo]

i get a slight flutter when i am not fully boosting. like there isn't enough pressure to open it all the way and give it that psssshhh sound.

he was talking about the greddy BOV when he said search. there is a big thread over here about it and a big thread over at dsmtalk about it. they are pretty hard to set to perfection, but once you do it is one of the best BOV's on the market.

 

[kpt4321]

AFC tuning shouldn't have an effect on the BOV.

You're right, it *shouldn't* open up except for when you lift off the gas. That's why this is a problem.

Like I asked, does the BOV have a boost reference port?


....Kyle T.