Hi Guys,
I have searched and read endless amounts of threads and have visited:

Mazda RX-7 3rd Gen Stuff

I followed all trouble shooting suggestions but I still can seem to be able to fix this problem. I was hoping fellow members can give me their opinion on my boost problem.


The problem that I'm having is that I have the following boost pattern:

3500 - 4,500 rpm = 12psi
4,500 - 4,600 rpm = 10psi
4,600 - 5,600 rpm = 12psi
5,600 - redline = starts to drop and stabilizes at 5psi

Here are my mods:

silicon vacuum lines
street ported motor
pfc
bnr stage 2 turbos
dp, mp, catback
intercooler
intake
fuel pump
larger injectors
greddy profec b boost controller
removed: ac, air pump, double throttle, air control valve, egr
light weight flywheel

Thanks in advance for your help.

 

Interesting.

Since you are able to achieve 12 psi before and after transition, it sounds like your sequential system is working properly, and you don't likely have a boost leak.

That would lead me to believe that the boost controller in your pfc and/or Greddy controller is set too low, or malfunctioning. Where do you have the boost controller set on the pfc?

The only other thing I can think of is wastegate not working right??

 

The boost controller is set at 12psi. I don't think the pfc boost level is set at anything. The stock waste gate and prespool solenoids have been removed. I currently have the 2 actuators capped off at the opposite end of the vacuum coming from the primary turbo housing. When I turn off the boost controller, it will maintain 5 psi boost through all rpms.

I tried to blow cigar smoke into the brake booster leading into the upper intake manifold while the car is off. I see cigar smoke coming from, what looks like the area near the exhaust manifold. The only vacuum lines I can think of down there are the 2 lines leading to the turbo control actuator. I will jack my car up tomorrow to check those lines again tomorrow but it seems like my sequential system is working but is just vent boost or exhaust or something is restricting the flow from 5,600 rpm - redline.

Driving me crazy. I bet it's some stupid too.

Thanks for your help

 

The pfc has primary and secondary boost control settings. You should find them on your commander, and see where they are set. You may have 2 boost controllers trying to do different things.