My mods are intake, dp, mp, cb, pfb. 93rx7 on stock twins.

I set my pfb boost at 10psi. It pulls solid 10 all the way to redline in every gear in my numerous encounters.

PROBLEM

One night after a run in with another car, my boost suddenly died. I pulled over and shut off my motor. Fifteen minutes later, I started her up. Took her out for a spin and noticed my boost would not past 5 psi. The next day I disconnected my profec B, and returned it to the stock boost setup. When the first turbo kicks in, I get 7psi, then the second turbo kicks in, which increases it to 10 psi, but as soon as I hit 5500-6000rpms, boost will drop to either 0 or 5 psi only. If I connect her back to the pfb, I get the same results.

Today, I removed all hardware to reach both sides of the turbos. I proceeded to spin both of the turbo fins with my finger, and they are smooth and quiet. I checked all the hoses and they appear to be fine, no cracks.

What can be wrong with my Rex???

What should I check???

My turbos couldn't be bad, could it???

My car idles and drives fine but I can't get the boost up.


I'll be working on her for the next couple of days so I'll appreciate any advise you guys can give me.

 

i have the problem with my secondary...so i'm interested in this

 

If you have checked for popped off vaccum hoses and boost leacks (specifically, the y-pipe coupler), then maybe a solenoid is broken. Check here for lots of info on troubleshooting boost problems:

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

Good luck.

 

I have a VR 93 FD. I just found out via my turbo boost gauge that my second turbo is not kicking in after the first one engages. I know that the pattern should be close to 10-8-10 but it's like 10-8-4. everything is stock except dp, aluminum ast. I'm checking the vacuum lines but are there any other possibilities? I appreciate all the help. Thanks. Em

 

mine spikes to 10 and then goes back down to 5-6 on the secondary

 

you should indeed check around the y-pipe there is also a valve there that i have seen sometimes get stuck closed also check the two selenoids for turbo control and pre-control they are the two that bolt on to youre intake manifold

 

Check the control actuators themselves. The actuator arms are secured by a small c-clip and they can fall off and cause erratic boost patterns.

 

Thanks guys,

I'll be testing the solenoids,valves, etc., as soon as I purchase a (air pump?).

Give me some time, and I'll report the results.

 

Just finished my car last night and took her for a ride. Wow, I've forgotten how fast this car was, boosting perfectly all threw the rpms.

The culprit, you ask? It was the 3" rubber hose connecting the y-pipe. It had a two inch slash above the clamp.

I couldn't believe this was the problem when I initially discovered it. So I basically took apart my motor and tested all the selonoids with a vacuum pump.

Well I learn a little more about the car.

To everyone who has eractic boost, sereiouly, you must first take out all those stock 3" rubber hoses (air box hoses, intercooler hoses and the y-pipe hose, etc) and squeeze them because it very difficult to check for cracks when they are still on your car.

I'm sure I be back with more issues in time since my 7 is 10 years old. But truly, I thank those who've responded with possible solutions.

 

Glad you found the problem .