When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Second that. I left permanent tees in my TCA lines in case I need to diagnose. It's an easy test once you find the hoses. You can tee in up top right next to the y pipe/crossover pipe and then just go for a drive.
Thanks for the responses guys! You're keeping me motivated!
If you're talking about the valve on top of the Y-pipe just under the secondary air intake then I've already tested the pressure side and it makes 10psi. I pulled off the vacuum side and heard it hiss meaning it has vacuum which I had read is a pass. Am I wrong? I've run out of ideas other than pulling off the UIM and trying to test solonoids.
If I understand what you are saying is that if this valve is not working than after the transition the secondary turbo's wastegate opens to bleed the boost off and I also loose the primary's boost since it's now feeding the secondary.
Wrong actuator. The TCA is the big turbo actuator attached to the exhaust manifold under the car. You don't have to tee in under the car, though. Take a look at these diagrams for TCA location and control system.
Oooooooohhh! Man, that was a real breakthrough reading the last few posts and then seeing those diagrams. Thanks a lot! I'll go poke around and see what I find. It's pouring rain here but it'll be worth taking the car out in it if I can find the problem.
Okay, here is what I found. I traced those to hoses up to right under the hot pipe. In the picture the aft hose (vacuum) has been replaced with a hose with a tee in it hence that white piece.
The forward(pressure)hose made 0 psi until 4500rpm and then 6.5-8.2 psi after 4500rpm. The aft hose(vacuum) pulled 0 hg at idle and then 16.2-16.8hg at WOT after 4500rpm. When the throttle was released it pulled 23.4-24.2hg until the RPM dropped below 3800rpm.
So uh, yeah, that's what it does. I unfortunately don't know what it means. Did we find the issue?
Sorry if I missed it, but has the boost ever worked, or did you just get the car and it was like this? Just curious if you changed something, then you had a boost issue.
It seems as though the pressure and vacuum lines to the tca are operating fine. You can also pressure test them with a mighty vac to make sure there are no leaks. Also, just like the WG and Precontrol Actuators, make sure that the arm of the TCA is connected properly to the flapper door.
Since primary boost is fine, I'd focus on the CRV and its hose, the Precontrol and wastegate actuator solenoids at the front of the uim (maybe the pugs are switched?) and the charge control butterfly valve and solenoids.
Sorry if I missed it, but has the boost ever worked, or did you just get the car and it was like this? Just curious if you changed something, then you had a boost issue.
It seems as though the pressure and vacuum lines to the tca are operating fine. You can also pressure test them with a mighty vac to make sure there are no leaks. Also, just like the WG and Precontrol Actuators, make sure that the arm of the TCA is connected properly to the flapper door.
Since primary boost is fine, I'd focus on the CRV and its hose, the Precontrol and wastegate actuator solenoids at the front of the uim (maybe the pugs are switched?) and the charge control butterfly valve and solenoids.
The boost used to work and it stopped while I was driving. All the actuator arms are attached. I have checked the CRV and it works. I replace CRV hose with a new one as it had a split. I know that the charge controller work since I teed into the pressure line. It built boost until 4500rpm at which point it all went away. If the actual valve is broken I don't know how to test it.
It seems as though all the mechanical parts are working so maybe it's time I pull off the UIM and start checking the solonoids. Does anybody have any other suggestions before I start that?
It may be the one or more of the solenoids are bad. The vacuum lines and the check valves are the other fail points. You may need to pull the solenoids to check each that are used for boosting including the CRV, turbo control (vacuum and pressure), charge control, and the precontrol and wastegate solenoids. If the vacuum lines are old, replace them all. If new, check them all. Same for the check valves.
Mike
Good - TCA pressure and vac are ok based on your results. That means you can rule out those two solenoids. Now use a mityvac to test the TCA itself on the car using the tubes you just found to have vac and pressure. See if pressure and vac do what they are supposed to do - move the rod.
You really have to test the signal to each component (vac or pressure) and then test the actual component (actuator, whatever) to diagnose the problem. You should be bench testing your CCV and CRV as well.
Last edited by alexdimen; Apr 9, 2019 at 11:41 AM.
Alex,
I know the TCA rod moves, I filmed it under the car going WOT. For whatever reason (format?) I can't upload it. The CCV(on top of the Y-PIPE) I believe works. I taped into the pressure line and it gets full boost until, you guessed it, 4500rpm and then loses it. I removed the vacuum line and it hissed. From what I've read that means it's all working, do I need to do more? The CRV is closed currently, if I go drive around and come back it's open unless I remove the vacuum line at which point it closes. This leads me to believe that it is functioning properly mechanically but I don't know if it's supposed to stay open like that. Any advice would be greatly appreciated.
Mike,
Above is what I've done on the CRV. I've already replaced all the one way check valves. I was wondering if anybody knew of anything else I should do before pulling off the UIM which would then make driving tests clearly harder.
I know you mentioned you capped the CRV, but did you do that after you replaced the hose? The CRV needs boost to stay closed. I noticed that when I had low boost at the transition there wasn't enough pressure to keep the CRV closed. I changed the vacuum lines a bit to correct this. This was also when running 16lbs...
Thanks for the advice! To be perfectly honest at this point I can't remember if I tried capping the CRV with the new hose or if I tried it with the old hose that I kinda repaired. I put two layers of hear wrap on it and went for a drive. It didn't blow out the tape so I assumed it held. I think I did do it again with the new hose but can't remember.
If I'm understanding your post you are saying that if boost is increased the charge control valve might not be getting the pressure it needs to open? So you tied it into the primary turbo as well. I guess that could be it. I have 99 spec turbos and we were increasing boost when this happened but I think only to 12lbs. I have a message in with my tuner to confirm the exact goals he was shooting for. I can go plumb it up and see if it helps.
Kinda. I put pressure on it and it's closed but I didn't put any current on it to see it it opens. I figured if it's closed so is the wastegate but I based that on nothing. Am I wrong?
Damn. Can we get a complete list of all the things you've tested and the results?
Something isn't adding up. Here's a thought - when you tied the CCV butterfly open and capped the CRV you got 10 PSI past 4500 RPM... right? Are you sure you tied the CCV butterfly open? Or could you have accidentally wired it closed for the test?
Well here's another thing to add to the list of things I've tried: Moehler's plumbing fix. Thanks for the idea but that must not be my issues since It didn't fix the problem.
Alex, no. When the CCV was open and CRV capped we still lost boost. Does this mean my wastegate might be suck open? As far as wiring the CCV open I'm afraid I also can't say. Afriend of mine who is helping me tune the car did that while I was working on something else. He's tuned a lot of FDs and has done this before so I assume he did it right.
I feel like we should have figured this out already. At this point I feel like a solonoid must have randomly died while we were driving.
Thanks for all the suggestions and keep them coming! It's helping me stay motivated instead of falling back into a car depression.
Also worth getting a copy of the vacuum hose diagram and double-checking that you don't have any hoses going to the wrong place. Big one to look at is the 4 vacuum lines on the outside of the lower intake manifold that go to the CCV, CRV, EGR, and Y-pipe.
Had a buddy with weird turbo issues forever, turns out he had the EGR vacuum hose and the CCV hose swapped or something like that.
I recommend to get a copy of the vacuum hose diagram and take it on a thumb drive to Kinko's and have them print it out on an 11x17 sheet of paper. If you really feel up to it you can have them laminate it for you. Should only cost a few bucks. I had one made up like 12 years ago that still looks like new. Makes a real handy reference when checking lines.
I chased turbo issues for a few months... It's not easy. Just need to triple check things, it will show itself.
The part that gets me is the hissing sound. Is it consistent? does it occur at all before 4500 rpms?
How old are the turbos, have you physically inspected the secondary turbo? Is the ypipe connection secure (no cracked bolts) and gasket in good shape?
If everything is in physically good shape, either the flapper door isn't opening (tca), the charge control butterfly valve isn't opening (solenoid F), or the CRV valve is venting (solenoid H). I'd tap each line while driving. Something has to not be working...
There is no venting before 4500rpm and after it is a very pronounced sound. It's hard to explain but it doesn't sound like a leak as opposed to something venting intentionally. A whoosh, not a hiss. The turbos are around 8 years old I believe. I have tapped the pressure and vacuum of the TCA, the results are above. I've also tapped the CCV which builds the required pressure and then loses it at 4500rpm. At this point I'm betting it's a failed solonoid and so I'll pull off the UIM and check them all. I just hope one is broken. If they are all good then I'm really be lost.
Good advice Dale. I just have them on paper pushpined to the wall right now. I colored it myself!
Thanks again for the responses. Hopefully in a hour or so I'll have some news.
If your solenoids are original, I would recommend replacing all of the "boost" related ones with new. I wouldn't trust old multiple heat cycle ones. They stick closed, stick open, leak, etc. Save yourself the hassle of doing any of this again in a few years. I replaced all of mine, again, the "boost" ones, and am glad I did. One other thing, I did receive two brand new ones that were bad from Mazda and had to return them for replacements. Make sure to bench test the new ones as per the thread in this forum for testing the solenoids.
Mike
