Interesting boost pattern issue
 

Ok so i've searched and tried to find someone having a similar problem to help narrow down the solution but have failed thus far. Anyone who can point me at the right system woudl be very appreciated.

Basically speaking, my car will hit 10psi on primary, and will go to 8psi and back to 10psi when the secondary comes online. Great right?

Ok the problem is if the car is running 3psi, and hits 4k, the psi will drop, and then you can hear the secondary turbine come online and the boost starts to build again.

Cliff notes: Secondary turbine is coming online without the primary getting a full 10psi.
Car has a normal 10 8 10 boost pattern when WOT


Help? lol

Have you replaced the check valves? I would start with that.

Yeah all were replaced with the VITON valves and lines, and i've checked directionality of them. Im well familiar with the issue of the turbines not going back to sequential and running parallel if a check valves bites the dust but this seems to be even weirder lol

Does the boost pattern change per gear? i.e. if you floor it from 1st or 2nd gear does it not get a full 10 PSI on the first turbo (I know it happens quick)? If that happens, does it work properly flooring it from 3rd gear?

1st through 3rd it will hit 10 psi, then 8, then 10 again like normal.

Its just when i go like half throttle it will go 5psi, then i can HEAR the secondary turbine come online and the boost will drop 1-2psi and then go back up to 5 and climb back up to 10psi if i give it more throttle with the turbos running in parallel.
OH and the mod list is in the signature if that helps any.

Only thing not listed is it is Vmounted now.

You might check this thread:

https://www.rx7club.com/3rd-gen-archives-73/weird-boost-issue-685269/

That seems to be the normal behavior as the ECU doesn't seem to use feedback on the primary turbo to bring the secondary online. I have the same effect both on a PowerFC and the stock ECU, it seems to be RPM based and above a certain RPM they run non-sequential regardless of the pressure.