Im new to twin turbos. So my question is, when the secondary comes on, does the primary get closed off? Or do they both go from 4500-redline? I ask that because at 4500 my boost falls down gradually to 0. I dont know if the secondary is not comming on at all and the primary isnt flowing enough, or if it is switching and the secondary is leaking somewhere. both turbos spin freely, no shaft play.. Any help would greatly be appreciated..

 

Both turbos should be running from 4500 up and producing a total of 10psi. Check the FAQ for the boost troubleshooting links.

Dave