Bad Wastegate, BOV, or something else?
 

Hi All,
Car runs great up to 15-18 PSI and boost flutters at max power... Running an FMII kit with a Garrett GT2560R and the standard FM bits. I tried to move the waste-gate actuator arm with my hand and its pretty hard to move manually. Thoughts on if these are prone to failure or if the BOV could be causing this? I have a Hallman RX Pro Manual Boost controller and it doesn't seem to be adjusting the boost level when I try to turn it up or down. Controller seems to be operating correctly with the adjustment line, which is what is leading me back to the waste-gate.

I thought it could be a leak but pressure is stable through the boost gauge at any given throttle position and there is no interference with the rev limiter in the MS3x that I can tell. It will also rev over 7k when idling.

Not that it matters but MSQ and Log file attached to see the flutter at max boost.

My bet is MBC. I also have the Hallman Rx running about 14psi and I have a bit of flutter too. It looks wierd on the logs but is otherwise unnoticeable. They are simple devices, take it apart and see if you can find anything wrong.

Are you seriously free revving your motor to over 7k rpm???

Thanks for the quick reply. I did take it apart and put the stronger spring in to see if that helped and no luck. All looks clean and it seems to be operating correctly. When it hits it's flutter around 15PSI and around 4500 RPM that flutter doesn't allow the car to rev past the 4500 mark under load...

BORKA - Just blipping the throttle to make sure there wasn't a rev limiter kicking in past 5-6k

If you you cant get past 4500rpm under load, you got a whole nother issue, not related to your turbo, Bov,or mbc

Your engine/tune issue is causing the flutter, not the flutter causing your issues

To me sounds like a missfire/spark blowout.

Stock coils?
Proper ngk plugs gapped properly?
NA8 car?

I appreciate the feedback, looking at the Fuel VE table there is a spike in the fuel around the 4500 rpm mark and probably came from running Autotune for too long. I'll adjust and try again tomorrow. Thanks again for the feedback.
Side note, how can you test for spark blowing out, i've noticed some hesitation as i get into higher boost levels is that typically the only way to tell? And is the solution typically closing the gap on the plugs?

I'm guessing this.

Gap your spark plugs to .028. Or get macho coils that can handle it.

Im on stock coils still and I actually gap my plugs down to .020. Upgraded coils are obviously ideal but stock can get the job done in a pinch with smaller gaps. I run a 2560R @18psi. In order for mine to hold boost I had to get a stronger WG can, stock was a 7psi spring its got a 1 bar can now and itll hold 17-18psi to redline now with no spike. Running a forge MBC.

Wire you vaccum from wastegate to turbo to test the wastegate functioning properly. If it's good then your mbc is bad.

My EBC lets the 8psi actuator make 21psi so far. Maybe it will go further.

My exact symptoms (same boost and rpm) were solved with new and macho LS3 coils after wasting 2 hours of dyno time jacking around with it.

For prosperity sake, I gapped them to .28 and replaced the Chinese D585's with some junkyard ones and she's running like a champ again. I also upped the dwell to 4.5 in MS. Thanks all, -Jeremy

good to hear its running properly.

is your motor built? 18psi on a 2560 can banana rods

It is a built motor and thanks again for all your help.