R33 Wont Hold Boost, Fluctuating..

[blaikier33]

hello ive got an r33 gtst series2. ever since i moved my wastegate actuator the har has started to fluctuate in boost presure, it will spool up fine but as soon as it hits max boost, 12psi it just flutters, it also does it when i try to hold it at a certain boost, eg 8psi. the bov just flutters.

1st and 2nd gear arnt to bad but it get morer and more unstable as i go through the gears. i adjusted the wastegate beacause it was sitting open about 3. 4. mm

mods include

hdi front mount

dump pipe back 3.5 inch exhaust

gutted stock cat

greddy inlett

tomie afr

supper spark coil packs

ngk r iridium plugs gap .8mm

high flow turbo

gfb bleed type boost controler

3inch inlet hard pipe

boxed pod

drift bov

getting nistune ecu soon

it was a lag machine sinse i adusted the wastegate, now it is responsive as but flutters

[lachlanw]

how did you move it ? and wtf is a "tomei afr"

where is your bleed valve plumbed from and where is your bov plumbed from ?hopefully not the same line. is the bov adjusted so its closed at idle ?

[paulr33]

has this turbo ever worked?

the fluttering occurs from compressor surge

compressor surge occurs when the pressure past the outlet of the compressor wheel exceeds what the compressor can actually supply. that is, the compressor and its map dictates as the best possible efficiency it can supply say 10psi of pressure (lets say) but when its running on your engine pressure past the compressor is actually reaching 15psi. the end result is the compressor surges and you get fluttering when its on boost. this is typical of mismatched / mangled highflow setups and/or mangled intake setups.

so has the turbo ever worked in the past at this boost level? if yes, check basics boost control and intake

if no, then check where the turbo has come from? it could be a mangled highflow spec and it might not even work at the boost levels you are trying to run, ie: it may always surge at 12psi or whatever you are trying to run

[hypergear]

I've seen 2x people has this problem, The turbo just surge after 10psi and car doesn't make any power, after turbo upgrade it was doing the same thing but surging more violently due to bigger size. Both cars were R34s with RB25det Neo engines. no idea what's causing it.

the stock comp housing should have no issues supply 18psi assume turbo it self can handle it. if the turbo seems to be in a good nick then it might not be it.

[paulr33]

don't confuse the BOV being the cause of the issue (the original poster), its doing what its meant to do

when pressure in the manifold surge's to a mega level - ie when you close the throttle body, the bov opens and dumps the pressure

so when yours is ramping on boost and the issue (whatever is wrong) occurs, the pressure in the manifold surges (ie compressor surge) and the BOV opens because the pressure instantly surges to spastic levels. i believe the compressor wheel is at fault, i would first pop the cover off and check the compressor for any damage / basic level inspection. if it looks ok i would take the turbo off and get it checked by a workshop. make a call then if its worth fixing or not (ie a new turbo could be cheaper than fixing a mangled compressor, depends on whats wrong)

[MrStabby]

so when yours is ramping on boost and the issue (whatever is wrong) occurs, the pressure in the manifold surges (ie compressor surge) and the BOV opens because the pressure instantly surges to spastic levels.

Yeah but the BOV wont have a vacuum signal on the diaphragm so you would hope that the spring would keep it shut.

Is the drift bov adjustable? Maybe it was always stuffed but did play up until it saw the higher boost you got after fixing the wastegate?