Tuning a grainger valve

[tttype]

Just installed a pop style boost control valve.
Set spring mid length to start, hit 20psi , no boost spike at all, just about perfect.
Turned in screw one turn, get spike to 22psi, then levels to 20.
Turned in one more turn, spikes to 24, then settles rock steady to 20 again.
Thought actuator may be to loose, turned in 2 turns ( about 1/4" preload now) no change, so is not wastegate.
Am thinking the spring may be to weak ?

Anyone have same problem ?

 

[tttype]

Put a much stronger spring in & still have the large boost spike.

Tried a freinds good grainger valve & its spiking also.

Opened the wastegate hole in turbo as large as I dared a few years ago, to closely match THDP puck.

Any sugestions on curing boost spike ?

 

[Sleeper1987]

hoses to small to the valve or excessive lenth?