scamil87

iTrader: (3)

Alright so i just finished my vacuum hose job and i gotta say the car performed a lot better than what it used to be but sometimes i still get the no transition issue described in this thread here (https://www.rx7club.com/3rd-gen-archives-73/weird-boost-issue-685269/). I changed all the solenoids in the rats nest and tripled checked every hose and everything else in there before i took the car out for a ride. Now ive been reading about different routes to take to address that problem and i came around this write up by damian (https://www.rx7club.com/3rd-gen-archives-73/my-boost-control-setup-perfect-10-8-10-pattern-178136/) and i was wondering if that would be the solution to my problem.
I know that on the first thread some of the guys, including Dave Disney solved the problem by plumbing a grainger pressure relief valve onto the pressure line between the pressure chamber and pressure turbo control solenoid. On Damian's write up however he installed the two hallman boost controllers on the lines to the wastegate and precontrol actuators.

So can anyone tell me what would be the best thing to do in my case. Ive been reading so much about boost issues that i cant really pick out what the best solution would be for me anymore and its driving me up the walls!

sbnrx7

iTrader: (4)

Did you check the actuators? They can actually fail. I found on my car that the Turbo Control actuator was bad....solenoids were fine. This made a huge difference in boost pattern once I found the problem and replaced the actuator.

scamil87

iTrader: (3)

ill double check on the actuator too.
but i was kinda wondering wat would be the best way to control the TCA
with some kinda of boost controller so i could ditch the solenoids.
thanks
Stephan

sbnrx7

iTrader: (4)

I haven't heard of anyone using a boost controller for the TCA. Remember, this particular actuator uses both pressure and vacuum to operate correctly. You can use a boost controller to operate the pre-spool and wastegate actuators though. Best bet is to test everything. On my TCA, the vacuum side was fine but the pressure side had an internal leak and wouldn't hold any pressure. Picked up a used one in the classified section and now the car is boosting fine .

scamil87

iTrader: (3)

Ok, and say I gotta pull the TCA out to test it out or to replace it. What's the procedure? It looks like some major PITA! Any tips?

IMZman

iTrader: (1)

If you are real good...you can just jack the front end up...remove the 2 metal heat shields, pull the vac and pressure lines and plug a MityVac tester onto either the vac or pressure side and test that the rod moves and holds. FSM says to test pressure side, see that actuator arm moves when applying 7.1 psi and arm releases when pressure is released. Do not use more than 11.5 psi.

Rod should start moving around 4-5 psi, and not ease back in with 7.1 psi applied. Watch for slow leak...arm will ease back in. Should not move at all.

No test is described for the vacuum side, but arm should move fully by 5 psi or so. Same deal, make sure there is no slow leak. Rod arm should not move.

If the rod arm does not hold during vac or pressure test...hit the WTB in the classifieds and you can find $25 to $35 used ones...may or may not work...no matter what the seller tells you...used is used. A new one goes for $500+ through Mallory Mazda.

Testing either on the car or removing the TCA is a PITA. Getting the lines back on can be a challenge. Go to church and pre-confess you sin of using the Lord's name in vain multiple times...before you start.

I did not read the links in your OP...if you are getting 10 inches of boost (assuming stock engine) during the "3rd gear" test after 4500 rpm and the boost bleeds down to 7-ish as you continue to red-line...the TCA can be one of the culprits. If that is not happening...save yourself some knuckle skin and cursing and look elsewhere.

sbnrx7

iTrader: (4)

^^^^What he said. You don't have to remove it to test it. There are two ways to do this. First, you can locate the vac and pressure lines on the top side of the engine that go to the TCA and hook your Mytivac up to the lines there. Just have someone under the car to confirm arm movement. Second option is to jack up the car, remove the front passenger side wheel (for easy access), and attack it directly. The pressure line is easy to access...vac side not so much. In the event it's bad, buy a used one. Also, it can be replaced without lowering the subframe or jacking up the engine. It is a massive pain but it can be done.

Steve

scamil87

iTrader: (3)

Okay let me fill you guys in on that facts by starting from the very beginning. Before my vacuum hose job i installed the boost gauge and the boost pattern was around 10-7-7. So i went to town on the **** and did the full vacuum hose job. While i was taking the car apart i noticed two things. The connectors to the wastegate and turbo pre-control solenoids were swapped AND the "E" clip on my TCA rod missing and the rod was not linked with the pin thingie for the flapper so i thought that was probably the reason for my 10-7-7 boost pattern. So after a few days with the car out and a few hundred dollars after i finished the hose job. Put it all back together and took the car out for a ride yesterday. I noticed improvement on the first couple of pulls and the psi reading were right around 10-8-10. But after a while i started getting the same issue i had before thats described in this thread here again (https://www.rx7club.com/showthread.php?t=685269). And then after that i started noticing to the psi reading and what i was actually getting was full primary boost and no secondary boost as the rpm went up. So it would start at full 10 and gradually decrease all the way to zero like a 10-5ish-0 pattern.

So thats the full description. You guys think these symptoms relate to the TCA. I just kinda wanted to get an idea of where to look at exactly cause like IMZman said, if i can save the cursing and the knuckle skin then i think i deserve it after that frigging hose job.
I appreciate all the help and attention so far. And many thanks to you Steve youve helped me out a great deal with these problems so far I can't thank you enough.

Stephan.

sbnrx7

iTrader: (4)

Not a problem at all man, glad to help. So, report back on the TCA so we know the status. Another item you need to check is the Charge Control Valve (CCV). This is another actuator that depends on both vac and pressure and if not operating correctly can certainly affect boost...plus its pretty easy to access and test.

Steve

scamil87

iTrader: (3)

alright so i got under there and tried testing the TCA. I was having a tough time with the vacuum side so i decided to pull it off and check it out. Turns out its not as hard as i expected it to be, so not a a lot cursing which was good.
Now as far as the TCA you guys were right on the money. The vacuum side was actually alright but the pressure side was leaking like crazy. It wouldnt even hold any pressure it would just leak right out. So im gonna go hunting for a good used one and i'll post the results. Appreciate the help so far guys.

scamil87

iTrader: (3)

Oh almost forgot. When i was removing the TCA i broke one of 12 mm bolts that hold the little bracket on the TCA to the turbo assembly. So i removed the TCA by unbolting the 2 10mm that go on the TCA itself and pulled it out. Now on the bracket i have a solid 12 mm bolt and a stud thats stuck. I mean its in there good and wont go anywhere. What does that hold and should i be concerned?
Thanks

sbnrx7

iTrader: (4)

That's great that you found the problem. I think I paid around $25 for a good used one on this site. As far as the broken bolt/stud, can you take a picture so we can see its location? I too had a stud break on the TCA during replacement.

Steve

scamil87

iTrader: (3)

Okay so i received the used TCA i bought and installed it. Car ran good but i had a feeling it was only doing the transition properly when i was on 3rd gear. It was really smooth on 3rd gear and i could really feel the secondary kicking in right around 4500 rpm. On 2nd gear was a little different though. Sometimes i would notice the secondary kicking in, sometimes i wouldnt, sometimes it would be a little delayed. Im not sure if its because when you're in second gear you get to redline faster than you can notice the transition from primary to secondary or if there actually is something wrong with it still. Please chime in if you guys think i should look at something else as well.

Oh and I took a picture of that bolt i broke.
Circled in green is the bracket that holds the TCA to the turbo assembly. The red circle is where i broke the bolt head. The stud is in there good and the bracket is solid. Is that bolt holding anything else that i should be concerned? Thanks.

scamil87

iTrader: (3)

bump for any comments on the bolt head described above.
Thanks
Stephan

sbnrx7

iTrader: (4)

The bolt you broke only holds the TCA bracket. Now, there are no guarantees how long the other one will last because the head on that one is exposed to the loads of the TCA. The little bit of threaded shaft that is left will likely absorb the shearing forces but there are also tensile forces exerted on the heads. One is gone and the other has to make up for it. Easiest solution would be to pull off that bracket and soak the broken bolt with a penetrant such as WD-40. Let it soak a while. Then use large vice-grips to see if you can get it out. Otherwise the other bolt will likely break over time and then you’ll have double the problem.

Just my engineering assessment.

Steve

millennm

iTrader: (6)

Here's a TCA test I did. I was just applying and releasing pressure though.

Ohseyun

thanks millennum for the video clip.

I've been having similar problems as well and the only way to attain full 10psi is to launch at 4000rpm on first gear and shift at redline. If not, the transition to secondary is unreliable, anywhere from 3-7psi.

Has anyone considered the Pettit Blueprinted CCV assembly? I've been told it could solve the lazy transition into the secondaries.