my rx7 boost to 10psi and holds for a few seconds then around 4500rpm the boost keeps dropping to around 5psi, can anyone help me? what is going on and what are some good things to check for?

mine did the same. as many others do also. im pretty sure it has to do with the wastegate. porting the wastegate i heard works. never done it myself so i cant be sure...

your secondary is not operating properly...

since your building 10psi on the primary.. id check the vaccuum and pressure side of the tca..

this is of course with the assumption your on stock sequential twins..

yes im on my stocks, i want to replace all my vacuum hoses this weekend see maybe if that works, if not are there any other suggestions that come to mind?

Porting the wastegate helps for overboosting. Not for a secondary turbo with no boost.



If I had to guess I would guess that the pre control actuator rod is sticking or even as Jio suggested the TCA. It's common for those actuator rods to get sticky and not move smoothly. That's looking at it from a mechnical point of view anyway. I don't know that seqential vacum system well enough to advise outside that.

A friend of mine has a single turbo its from a series 5 engine and has the same problem. The boost holds good till about 4500 RPM but steadily drops off till about 5psi. Im thinking that it may be leak of some sorts though, or could this be the wastegate was well?