I am not sure if I have a problem. I do not feel a second turbo boost and my boost seems to go from about 12 pounds to 5 in third gear at around 5000 RPMS. WHat can I do to check for problems?

Thanks...

mforrest@cassling.com

 

vacume lines change them all It should fix the problem

 

I respectfully disagree with jet7. The problem may be a solenoid, actuator, or check valve, in which case changing all the vacuum lines won't help.

Instead, try this place:

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

Read EVERYTHING on that site. Make sure you understand how the sequential turbo system works, then follow the troubleshooting steps.

With low secondary boost, it could be any number of things, so it's best just to check everything. Here's a checklist...

all check valves
Vacuum chamber
pressure chamber
any loose or disconnected hoses
y-pipe coupling
intake hoses
Turbo control actuator (TCA)
TCA solenoids (both of them)
Charge control actuator (CCA)
CCA solenoid
Wastegate actuator
Wastegate solenoid
Precontrol actuator
Precontrol solenoid
Air Bypass Valve (ABV)
Charge Relief Valve (CRV)

All these things will make sense when you read that website. I'm sure people here will help if you have problems figuring something out, but it really helps to have a basic understanding of the system first.

Good luck (you're gonna need it )

 

changing the vac lines on my car fix the same problem. I checked all the controls and It led me to changing the lines for the 2nd time hey you never know

 

Yep, this the exhaustive list to go through when troubleshooting a secondary turbo problem. I've crossed off 95% of the list. I'm down to the CCA, CCA solenoid, and vacuum chamber. Currently the KOKO (key on/key off) sequence doesn't pull the CCA rod in/out, which points to a leaky vacuum chamber. If a new vacuum chamber doesn't do the trick, I guess I need to look into the CCA stuff dammit!

 

FWIW, my problem was a vacuum chamber completely filled with OIL! Replaced the chambers (both pressure and vacuum) with a new chambers, and the second turbo comes online properly now. I also replaced the PCV valve with a new one to prevent the vacuum chamber from filling up again. A bad PCV will pressurize the oil pan (when under boost pressure), causing an oil mess @ the filler neck, and forcing more oil through the primary turbo, thus oiling the entire intake tract. The oil will work its way through the vacuum lines, and will ultimately fill up the new vacuum chamber again.

 

Check out my old thread.

https://www.rx7club.com/forum/showth...hreadid=181539

 

My turbo control actuator was not clicking over when you key the car ON. That led me to find a missing hose and check valve in the system. That walkthrough is golden!

After I got that working I had 2ndary turbo again. albeit at 7psi until i foun the 2in gash in my y-pipe coupling! Now it runs scarrry fast!

 

Seems everyone has something different plaguing the second turbo control system. Goes to show there could be several places in the turbo control system that give the same symptom (second turbo not coming online @ the switchover 4500 rpm)...