I have an Rx7 year 97 and I have a problem with boost, when it goes above 4500 rpm boost will drops to 0 - 2 psi only, anyone can HELP me urgently plsssss

97' hu? you in Japan? sounds like a vacume problem. cant help you more than that.. got rid of the stock turbos a LONG time ago..

Any abnormal noises above 4500 rpm like air escaping?



Check the outlet hoses for the secondary turbo for leaks/cracks.



Could be a dead secondary compressor wheel?

No there is no noises and even we checked all the hoses.

While I'm no expert, the minimum boost you should see is 7 psi, as that is what the wastegate spring is set for. With this considered, I would have to second the other's opinions in that air is most likley escaping somewhere in route to the intake manifold. The stock coupler on the tube that snakes to the right of the water filler neck is not the greatest.

I just fixed a car with those symptoms.



Assuming that the hoses aren't too much different on your '97, tap a boost gauge into the vacuum line on the second turbo side of the Y pipe. You have to dig a little to get to it, but not too much. It's on the portion of the Y pipe that the second turbo feeds. That portion is closed off until 4500.



If you see pressure there before 4500 then your second turbo is spooling up and the problem is in the transition and you'll need to find out why the transition isn't happening. For example, if the charge control actuator isn't opening you'll get the symptoms you describe.



If you don't see pressure, then the second turbo isn't spooling up and you'll need to find out why. Precontrol failures can cause that.



On the car I just fixed, the second turbo was spooling up and the problem was a vacuum line (under the UIM) that was part of the charge control circuit.



Good luck!

The joy of stock turbos and a million vaccum lines = FUN