First off I just want to say I'm a new commer to the 13b and the Twins. But I do have years of experience with engines and automobiles. So if you guys can please help me out with some good feedback I'd be more then appreciative.

My 93 Rx7 had a bad Pre turbo Control Valve ( pictured below from PETTIT RACING) the solenoid on the unit was malfunctioning and sticky causing my car to fall on its face and not boost properly. So, I replaced the unit with a newer one, however, I noticed that the ADUSTMENT screw on the unit was not matching up with the stock setting from the unit that I removed.

So, I decided to match up the new units adjustment screw to the same setting as the stock unit and I reinstalled the Pre control valve. And then I took it for a test run. After doing that I notice that the cars boost pattern is not going passed 5PSI and at sometimes even lower. So, at this time I figured that maybe the new unit was pre adjusted the correct way. So, I adjusted it the opposite of what is pictured below.

Took it out for another run and now the car boosts to 10 -12 PSI but the secondary turbo doesn't hit untill later in the RPM RANGE around 6k.!?!?

So, with the picture below from pettit racing, as stated by them *BLUEPRINTED* Does it control PSI levels and the engagement point of the secondary turbo through adjustment either away from stock position or at stock position?

Does adjusting that screw and lock nut control PSI PRESSURE AND SECONDARY turbo engagement??? I'm just trying to get the car to run at stock PSI Levels. Thanks guys

AT THIS POSITION IT ONLY BOOSTS 5 PSI

 

Stock ECU?

thewird

 

check the other solenoids and see if theyre working?

 

k i see you replaced the turbo precontrol valve, forgive me if this is wrong but what about the turbo precontrol solenoid? because I know that if the solenoid were for some reason to be held open then the precontrol valve would stay closed, and the secondary turbo wouldn't preboost...and that might be why your not feeling it kick in until 6000 rpm? Im not sure how relevant that is to the entire problem but...maybe it could be something to consider? ...Hope its in any way helpful..
--EDIT-- forgot to mention i know the turbo precontrol solenoid is controlled by the ECU...so...it could also be that the solenoid is receiving improper signals from the ECU...just some more food for thought...

 

The thing in the picture is a charge control valve. It's not a controller in any way - it is an open/closed function that allows the primary and secondary to work together. The only thing it could do incorrectly is get in the way of full boost above 4500.

Dave

 

pre control is on the exhaust side. it is almost like a wastegate, it controls flow of the exhaust air. the charge control (pictured up there) and charge relief (vents air back to the airbox as the secondary turbo is spooling up but not fully online) are on the compressor side.

 

Sorry, I should've mentioned earlier for some reason the pictures wont load for me right now..so i was going purely off of what was said. And not trying to jack the thread or anything here but...why wouldn't that still be a possibility for delaying the secondary turbo's full boost till 6k rpm? sorry, just trying to get me some learnin haha

 

I suppose if you have the adj screw down too far, it will keep the CCV open, meaning the secondary doesn't prespool properly and it takes till 6k to get fully spooled again?

 

dgeesaman
"The thing in the picture is a charge control valve. It's not a controller in any way - it is an open/closed function that allows the primary and secondary to work together. The only thing it could do incorrectly is get in the way of full boost above 4500.

Dave"


Hey guys thanks for the responses. And YES that unit that is pictured is the Charge Control Valve (CCA) and not the Pre turbo control valve.
I just adjusted the Screw to opposite of the picture above.
So if im understanding this correctly . The CCA doesnt control boost in any way , then why having it at stock position only yeild me 5PSI max and makes the boost spool really slow and then WHEN I adjusted it to opposite of what is pictured above it allows me to boost to 10 PSI? but still bleeds off on the higher RPM. And now it doesnt feel like the secondary is even hitting now.

So now im thinking what controls the secondary turbo to boost after the primary has reached max psi? What should I look for or check ? turbo precontrol solenoid?

 

From the fAQ thread:
http://www.autosportracetech.com/RX-7/rx7stuff.htm

 

If your transition is correct you shouldn't feel the secondary hit like a brick wall. In many cases the brick wall transition feeling is bad because it means you're getting a boost spike at 4500. The transition should be as smooth as possible.

There is no official information about how that adjustment screw should be set. It does not control secondary boost pressure. It limits the travel of the CCV, and IMO it should be set to allow the valve to move through it's full motion. If that arm touches the screw, it means the butterfly valve inside isn't fully closed, that you're bleeding boost and not getting a good prespool.

Secondary boost is controlled strictly by the wastegate system. On a stock FD that's a non-adjustable solenoid which can be tricked using a PFC, adjusting the restrictor pills, or replaced with a boost controller. The boost controller is the superior method, although for near-stock situations using the PFC works well too.

The transition is governed by several things that must all happen at once: the CCV must open, the CRV must close, and the turbo control door must open.

By the sound of this:
You might be close to correct here. Your boost should be 3 levels: constant before 4500, a slightly lower number at 4500, and a constant level above 4500. What is yours doing compared to how I describe it?

 

it boost striaght to 10 PSI with a slight hesitation at 5 PSI and then to 10Psi and will hold untill the higher RPM's. but will bleed off. at the higher RPM.

 

http://www.autosportracetech.com/RX-...ng.htm#Primary

 

The bleeding off at high rpm suggests some flow restriction. I would remove whatever cats the car has and verify the elements inside are not collapsed or loose.

The low transition is actually kinda common. Just about every solenoid and actuator is doing something at that moment.

Dave

 

Hey guys i was doing some reading and I was thinking since I adjusted this screw to the opposite to what is pictured, I think im leaving the CCV always open.. and if im understanding this correctly. In the stock position this valve is to remain closed untill there is enough pressure and eletrical signal from the ecu to open it to start to boost the secondary turbo. So, im hypothesising , since I adjusted it do you guys think im running a non sequential setup now since the air is going through both turbos as it sits and that explains the PSI increase?

 

If the door was always open you'd actually have low boost because there would be a leak in the system caused by the CRV bleeding boost before transition.

cf. https://www.rx7club.com/showthread.p...hlight=crv+ccv

The Pettit unit shown above is designed to deal with a low or lazy transition.