I have a 99 turbo miata with a begi turbo kit and Xede piggyback tune. i had a supposedly 10 pound spring in wastegate but when i flooored it id get 15 or more psi and start pinging loike a mf, switched it with an 8 pound spring now it hits 8 pounds then falls back then does this multiple times and if i keep my foot in it, it will hit 10 psi but it never holds it... just keeps pulling back, is this a tuning issue or wastegate issue? i was also told my wastegate is on ba ckwards and i am looking for confirmation from one of you, the exaust is a FM kit so i dont believe theres any backpressure but theres no boost leaks that i could find..im thinking its tune related. i have a video of it but im not sure how to upload videos. thank you all

 

Sounds like a boost leak

You can build something like this to test for leaks



Cap off the cold side charge pipe where it would normally connect to the throttle and use that^ on the turbo inlet to pressurize the system. Listen around for leaks.

 

WG sure looks backwards to me.

 

with the old spring I could feather it to hold 10 psi. Could that still leak? And he switched the wastegate and it still had the same issue. Thank you for the confirmation

 

If not using EBC, I usually prefer to route the WG signal line from the outlet side of the IC.

 

And where is that diverter signal line coming from?

 

im sorry, first turbo car. I’m not sure what that diverted signal is or where is comes from and I should route the pressure from the WG to the back of the turbo??

 

Found your problem

 

No, to the pipe between the IC and the TB.


The diverter is the valve between the intake and the pipe between the IC and TB. The vac signal for this valve should be taken from the intake manifold, after the TB.

 

This.