hi, got a problem and its driving me mad, basic b16a2 setup

stock b16a2
P fabrications log manifold
rc550 injectors
T3/t4 .57 (made in a cave but lasted 6months so far)
replica greddy type s blowoff valve
xs power 38mm wastegate
cheap ebay intercooler.
ball and spring type boost controller.

mostly cheap parts but been working for a while. only been running 3psi (wastegate spring).didnt raise the boost until i got dataloggin workin and could tune it, got wideband and everything but was havin problems. any way the real problem is when i raise the boost to 8-9psi at about 6500rpm it starts falling to about 4psi. holds 8psi in 2-3-4-5 but slowly drops everytime, thought it was a boost leak but pressure tested all pipes to 25psi (foot pump). any one got any ideas wats next to check ,

only happens at high revs and its pissin me off, im better short shifting than revin high lol. any help would be great , thanks


mike.

 

probalby that dinky *** turbo you have....

what exhuast /cat /muffler ?

 

assuming u dont hear ur wastegate open at all during these spikes from 8-3lbs?

lets see the bin aswell

 

exhuast is a 3" from the turbo (home made) muffler is a straight through cheap can sounds good though. can't really hear the wastegate(screamer pipe) over the exhuast. will hunt out the bin and post it .

 

bov working? maybe its not "tight enough"

 

tightened it right up before to make sure. think its the wastegate but dnt know wat would cause it todo that. its stiff fuel type hose from the inlet manifold to the wastegate. maybe the cheap MBC ?.

 

yeah i would definitely agree that its ur MBC just get a new spring