I have been working on this problem for a while, and can't seem to figure this out. I have read many, many threads, and have tried what seems to be everything. I have little to no boost on the primary turbo, but full boost past 4500 rpm. I have replaced the TC solenoid with a good one that I tested as per this thread: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-test-your-solenoids-actuators-other-turbo-stuff-802060/. I have new viton check valves too. I have checked the pre control actuator rod and it is closed. I have done the KOKO test and the CCA rod is pulled in when the car idles. I even zip tied the actuator shut and could now build primary boost. Any ideas? I know this has been talked about many times, but I can't seem to find an answer. Thanks for any help.

 

hi, i had the same problem because my pressure tank wasn't connected and the restrictor pills were missing. Also search for vacuum hose leaks. Good luck

 

Test the actuator and related vac hoses on your y-pipe.

 

There are two turbo control solenoids. One is in the rack and looks like all the others, it is designated "E" on the diagrams. The other is bolted to the ACV, and does not have a letter associated with it just "Solenoid Valve (turbo control)".

Have you tested both of them? In my experience with cars that exhibit the symptoms you are describing it was always the Solenoid Valve (turbo control) on the ACV.

 

I remember reading a thread where you(Banzia-Racing) fixed this same problem by installing a new solenoid. I replaced that TC solenoid with one purchased from a reputable forum member, but I didn't have a Mityvac at the time to test it. I guess I will test it to make sure. I don't think it is a boost leak, because I do have secondary boost, and I know the pills are in the lines. I forced the butterfly in the Y-pipe closed with a zip tie, and still no primary boost, only about 2 lbs. I tried hooking up a MBC to the procontrol actuator and closed it to try and force the precontrol door shut, and still nothing.

 

I agree with checking your pressure tank.

 

So wait, according to your OP, you said that you tied the CCA shut which made the primary work? But it would not work normally even though you can see the rod pulled in to close it?

 

No sorry, I tied the CCA shut and I still had no primary boost. The pressure tank works, because I can drive the car, shut it off, and if I remove a hose I can hear pressure escape from the tank.

 

I remember reading a thread (https://www.rx7club.com/showthread.p...=Primary+boost) with someone who had the same problem, and it was caused by really bad cracking in the manifold, but it seems far less likely that this is the problem. Has anyone else had this problem because of cracking in their manifold?

 

If all your solenoids and check valves are good, then you have a line routed incorrectly.