dump valve, whats happening?
 

hiya all, just had a fmic fitted and noticed one big chage, my dump valve used to go tssssss but now it goes tssss tsss tsss tss ts

any ideas on this?

Are you sure its the dump valve not the waste gate because the dump valve isnt opening?

My HKS SSQV (standard mount on TMIC) causes a chatter at lower boost, only fully opens at high boost. Whether, like Davey says, it's actually not opening sufficiently to vent and the chatter is the turbo blades being stalled by back pressure I dont know. Think I'll stick my recirc back on tho.

urm tbh i have no idea? any ideas what i should check? ill look at the pipes ect for leaks but apart from that im stumped

The noise is because the dump valve cannot dump the entire contents of the larger volume FMIC quickly enough. The air is then forced backwards through the turbo and through the MAF. I bet you get a judder when easing off the throttle sometimes? This is air going back through the MAF and confusing it causing the ECU to add fuel. At a recent mapping session, Andy showed me this in graph form on his laptop. Going back to a standard recirc will usually cure the problem to a certain extent.

if mapped right to sort judder sounds awesome, mate had it with his and have to say loved the way it sounded