Lepprykaun

Hi guys. I've done some searching and haven't been able to find anything like the problem i'm having. If anyone has a link that will direct me to a thread with info that can help me with this i would appreciate it. Either way here is my problem.

My car -

92 rx7 fd
No serious mods done
Apexi intake
full 3 inch exhaust with high flow cat
apexi bov
boost gauge
all stock lines, hoses etc

When driving and I give her gas, I get no boost, at all until i hit around 4500 rpm, then I hit 10 lbs. EXCEPT when i first start it up, let it reach operating temp, and then it does it once and once only where i hit 10 lbs and stay at 10 until i shift. It's quite hard to explain but on first run of the day I boost. After letting go of the gas I only hit 10 lbs of boost around 4500 rpm. It feels as if my primary turbo isn't working at all.
I recently fixed a few cracked hoses under the upper intake plenum which led me to think I found my problem but it just solved the idle issue i seemed to be having and not the boost problem. I also checked intercooler hoses and everything seems to be okay. I did not however get a chance to take a look at my y-pipe and coupler yet. I heard they can cause problems

Long story short, no primary turbo, just secondary coming online at 4500.

If i left important details out on my car please comment or send a link to where i might find this info. All the threads I seem to find focus more on secondary problems.

Thanks

Mahjik

iTrader: (1)

I would start with investigating the Charge Control Valve and Turbo Control. You can see what is active above and below the transition point (4500~ rpms) in the following link:

http://www.autosportracetech.com/RX-...erOverview.htm

Troubleshooting:

http://www.autosportracetech.com/RX-...leshooting.htm

CloudPump

iTrader: (2)

Sounds like your charge control valve is stuck open, this would dump your primary turbo boost out the charge releif valve until the secondary turbo is expected to kick in and the charge relief valve closes.

Your charge control valve is a butterfly in the Y pipe that is closed until the transition. This allows the secondary turbo to spool before it kicks in, but all of pressure created by the secondary turbo is dumped out the charge relief valve until the secontary turbo is actually brought "on line". If your charge control valve is stuck open, your primary and secondary turbo's are permanently "connected" and the boost of the primary will follow the path of least resistence out the charge releif valve along with any pre-spool of the secondary turbo.

-Geoff

Lepprykaun

Thanks a bunch, i'll check that out immediately. Can the valve be repaired or unstuck if that is the case? Or would i have to go about locating one?

CloudPump

iTrader: (2)

Testing is easy... with the key off the actuator should click open, with the key "on" it should snap shut. You should be able to see this happen on the "back" of your Y pipe. The charge control valve is located on the piece of pipe that connects your secondary turbo to the back of the Y pipe.

If this isn't happening, you've found your problem. If it is happening, you have more hunting to do.

I don't believe any repair is done to the actuator/valve. You'd have much better luck replacing it with someone who's gone single turbo and is selling this part. You should find plenty in the classifieds.

-Geoff