Hi have had a boost problem since i got the car about 6 months ago. Have replaced all vacum hoses which were in a bad state. Pre cat had broken up so have now got a new dp. cat was cleaned of pre cat. back box had melted and had a loose baffel plate.

The boost will go up to about 5.9 then 5.9 on second. some times it will reach 8 on primary but not all times. Iv checked for leaks and every thing on truble shooting websites.
Are the turbos bad. but why then go to 8 some times??

Am using a digital boost gage and am beginning not to trust it.
BTW. its a 1993 JDM

Hks induction mushroom filters aswell.

 

 

check the air inlet black rubber flex hose to the front turbo. mine was collapsing during acceleration. the only way i found it was in the colder weather, it stayed collapsed long enough to see. fixed with a coiled up piece of heavy ga. wire inserted into tube

 

Check all your intercooler piping carefully. Also, check that little rubber coupling between the Y-pipe and crossover tube. That tends to split on people.

 

tried with the intake pipe on primary turbo removed and still does the same. Also just noticed my boost gauge goin up to 19psi when i let off the throttle. just for a split second. not sure if this is my digital guage.
any more ideas before i go insane.

 

black box?

 

It's tough to know exactly what you have done when you say "everything on the troubleshooting sites". Have you benchtested all the solenoids, for instance?

Which "black box" did you replace? I assume that you are talking about either the vacuum tank or the presure tank? Have you checked that you are holding presure or vacuum on the appropriate tank? Tee a vac/boost gauge into the feed lines and check while on the road.

I would get an analog boost gauge for testing just to make sure that you can see the transients (I'm not a big fan of digital gauges).

Your 5.9 lbs sounds like posssibly an issue with the wastegate not being held closed. Check the feed to the wastgate actuator. If it's not good, backtrack from there.

Hope this helps,

-b

 

Have not replaced or touched a black box. i dont think i even metioned one??

 

all solinoids are working and am gonna buy a manual boost gauge

 

Do you have your restrictor pills installed?

 

What about your Y-pipe... have you checked that to see if it may be cracked?

 

I think they miss read your original post where you said "back box".
You need to check the boost control actuators and make sure it is still has a full range of motion. You can only check this from under the car.
By the way, you may also be having a problem with a bad boost gauge. The reason why I'm saying this is because the secondary wouldn't even come on-line if your primary turbo is boostin below 7 psi (you are talking about psi right?)

 

Iv replaced all rubber couplings and checked all pipes. pills are in there. Never been shore which is the Y pipe every one talks about. Is it aluminuim?? Iv checked the plastic one that goes to the intercooler.

 

The Y-pipe is the piece that is right below the plastic cross over pipe. It sits right above the turbos (next to the lower intake manifold) and joins the compressor output of the two turbos. It's difficult to see until you remove the cross over pipe.

 

I'd check the gauge if I were you. It's the simplist thing to check... just try another gauge. This does sound a little strange, and if you were spiking to 19psi, you'd probably blow you motor by now. does the car feel strong?

 

http://www.autosportracetech.com/RX-7/rx7stuff.htm

 

At last i found the problem. digital boost gauge was incorrect. am getting 10-8-10 now on new gauge.
just think about all that time and effort and it was the gauge.