Is there a nipple around here ?
 

Hey
I recently noticed that the nipple on my (stock 93 FD) Charge Control Valve was not plugged at all.
https://cimg7.ibsrv.net/gimg/www.rx7...5127c991fb.jpg

After doing some researches, I found out where it should be connected to the LIM bottom plug. But there was already a hose connected to this plug, and going down along the Y-pipe/LIM, So, at that point I was thinking that my mechanic had simply forgotten to connect this hose back on the Charge Control Valve. I couldn't see the other end of the hose but I expected it to be hanging loose, so I started to pull it in order to connect it back to the CCV, but when it came I understood it was connected to a nipple down there... so it was mistakenly connected on another nipple, but which one ?
Anyway, I connected it back to the CCV :

https://cimg3.ibsrv.net/gimg/www.rx7...18c82a95ef.png


Now, my first turbo charges a lot faster and got lot more power in the low rpms.
But, now when the second turbo is charging I can hear a weird hissing air sound, and the second turbo isn't really giving more power now... (before I removed that hose, it was)

Today, I removed the UIM, and spent one hour looking for a mysterious nipple let free in this small area but I never found it. The CCV hose being 10cm long, it must be pretty close near the LIM / Y-pipe/air pump... Tomorrow I'll try with an endoscope but If anyone has an idea, I'd appreciate because I'd like to avoid removing the air pump to get a better view.


https://cimg9.ibsrv.net/gimg/www.rx7...d0d612e1b5.png

Not sure if this will be too helpful, but here's a couple pictures of that area on mine which has no airpump-

https://cimg5.ibsrv.net/gimg/www.rx7...c1106a723b.jpg

In the lower area here are two nipples at the primary turbo intake


https://cimg6.ibsrv.net/gimg/www.rx7...b2a279a4d8.jpg
And in the spotlight here, are two more at the top of the Y pipe.


https://cimg9.ibsrv.net/gimg/www.rx7...e62eb49cfd.jpg

None of those pictured are supposed to go up to any of the four LIM pass-through nipples, so honestly my best guess (if I understand your story correctly) is that maybe that charge control hose was mistakenly placed on the charge relief valve, and now without vacuum it is constantly open, venting the secondary boost pressure out. Could you track down the Charge Relief Valve line on the diagram and see if it is properly connected? (Again, this is really just a guess)

Last picture (believe me, I tried to get a better one!) here's how the hose routing is on mine:


https://cimg2.ibsrv.net/gimg/www.rx7...9050626779.jpg
The pass-through nipples from top to bottom:
Disconnected top (non-turbo control related, I'm simplified sequential)
Second one down is the dark green on the diagram, goes behind the charge relief valve
Third down goes to the charge relief valve
Last one goes to the charge control actuator

Hope this helps!

Thank you for those pictures, It really helps.
Now I'm sure all my 3 pass-through nipples are correctly connected now (thanks to your last photo)
But, indeed, the last one (bottom one) was mistakenly connected to another wrong nipple, that's the one I'm looking for.
I think it could be one of the 2 nipples I can see on the bottom of your first photo. I'll keep searching ! thanks again.

There shouldn't be anything else down there it could plug into, unless it was going to the EGR valve or something. I seem to remember your car has the EGR not hooked up or something?

Pulling the air pump isn't hard, 2 bolts hold it in. It might be worth doing to get a good look at things.

The hissing noise could also be a small boost leak or a split vacuum hose.

Dale

Yes, you're right. My EGR valve wasn't connected neither.
Can I pull the air pump as is, I mean without removing the belt ? That would be great.

The thing is that this hissing noise was not there before I replace correctly the Charge Controle Actuator's hose. And even if I didn't see it, I really felt the other end of that hose attached to a nipple down there when I pulled it, or maybe it was just stuck between something else (explaining why I felt a small resistance before it came...) I don't know.

I haven't removed an air pump in a long time. You will need to move the belt off the air pump, you don't have to totally remove it, but you do have to de-tension the belt. You may have to loosen the alternator to get enough slack to remove the belt. It think there may be some adjustment on the bottom of the air pump, but again I haven't done one in YEARS (ditched mine a long time ago) so I can't recall.

Regardless it's not hard. Everything is easy to get to. If you can pull the upper intake manifold you have the skills to remove the air pump :).

Dale

Alright, that's good to hear ! :) The UIM removal wasn't hard at all in fact, I was just a bit more afraid of the belts :blush:
Thanks Dale

Well, I just took a look with an endoscope... and I can't find no niple in this area... so maybe that hose was really just stuck between another hose down there. So I was wrong to think it was connected to a niple. My mechanic would have just forgotten to plug it back on the Actuator, I guess.
In that case, I don't know why I never heard the hissing air sound before I plug it back on the Charge control actuator... :ponder:
Well, I think I really need to read and learn how a turbo work, and particularly this double one :)

Honestly one thing I might recommend is to go through the whole system and replace the old rubber hoses with silicone (I'm having a hard time telling from the pictures if yours are already silicone but black colored). In fact, even if yours are already redone I'd still recommend going through the exercise or even just zip-tying each one in place.

Not only does this help with reliability, but it really does kind of boost your knowledge of the sequential control system, as it gets you to think about each hose's purpose and how they all work together as you go through it. Really, I had a hard time understanding until I got my hands dirty! :)

Those colorized hose diagrams are also extremely helpful!

If you decide to do this, it might also be a good time to consider a simplified sequential setup, although I don't know how tough emissions standards are in France.

I asked my mechanic to replace all my ratnest's hoses with black silicone hoses 3 months ago (during the engine rebuild), but yes I really should go through all this by myself. My mechanic clearly did a few mistakes (the charge control actuator being one of them) so I better have to check the whole turbo system. I just need time and space (I can't wait to get that new garage in a couple months)
For the simplified sequential setup, I was thinking about it, but I really need to read and learn more about it before.

This is my first rx7, and my first turbocharged car as well. I didn't even noticed something was wrong when I drove it with the unplugged charge control actuator...
Did anyone here experienced an unplugged charge control actuator ? what are the usual symptoms ?

If it isn't working you won't get full boost after transition (4500 rpm) - either not enough boost or it will be lazy to open.

The charge control is just a butterfly valve. It stays closed below 4500 RPM so the compressed air coming from the primary turbo doesn't try and go down the pipe towards the secondary turbo and stall that turbo. The compressed air from the primary would go and push against the secondary turbo, basically pushing it backwards and stalling it. The CCV has 2 nipples, one goes right to the pipe and the other goes to the solenoid that controls it. The 2 inputs allow it to react quicker and snap open when it's time to open.

Do you have a boost gauge? What is your boost pattern?

It's also possible that the CCV is bad and has a torn diaphragm - it's not super common but I have seen it before. Super easy to test - move the rod with your finger and put another finger over the nipple the vacuum line goes to to stop air going in. The rod should stay put. If it slowly retracts the diaphragm is torn and it's not holding vacuum. If it is torn that could be the noise you are hearing.

Dale

Thanks a lot for the explanations Dale.
I recently installed the Defi Racer boost gauge indeed.
Now, when I WOT (starting from 2000rp) I've got 0,6 bar immediately, then around the 4000 rpm I've got the regular drop and then after 4000 (when that hissing sound comes) the pressure stays in the 0,3 / 0,4bar or so (but definitely not 0,6 bar again), so, from what you've said, it's like the CCV is not working, right ?
That's a bit strange that it's happening now after I plugged correctly that small hose controlling the CCV. When it was loose, I was in the 0,6bar after 4000rpm iirc.

Anyway, I'll test the CCV asap, thanks for the tip !

I'm also wondering something, when its controlling hose is unplugged, does the CC valve stays open or closed ?

This thread was not was I was expecting at all

The resting position of the Charge Control Actuator/Valve is Open (ie, car off, no vacuum applied). So if you had it unplugged, it would remain open. Not completely sure of how that might affect primary boost, but I imagine it would mean a bit less immediate primary boost pressure, and slower secondary spool. However, once the secondary does spool up, you'd be getting the full boost of primary and secondary, as is normal.

I wonder, now that it's plugged in if your actuator isn't being switched to open (just getting a constant vacuum). If that's the case, I imagine that after the 4500 RPM transition point, the closed valve would block secondary pressure from entering the intake and it also might reduce primary pressure because some of that exhaust gas is being used to spool the secondary (which doesn't do anything because its blocked by the valve).

That might result in
Before, CCA/CCV unplugged: slower primary and secondary pressure/spool, but full boost after transition.
After, CCA/CCV plugged but not switching: faster primary spool, but partial boost loss after transition.

Dale's test to confirm a working actuator is a good one, and another easy test to see if the actuator itself is damaged is on page F-87 of the factory service manual:
With the car off, the plunger should be extended, but with the car idling, it should be retracted. That would eliminate the actuator itself as a problem, but if that's the case, something still isn't right and will take some digging to figure out.
Good Luck!

Hey, what kind of nipple did you expect? :rolleyes:
ahahahhhhh

XanderCage, sounds like pretty probable to me. Can't wait to troubleshoot this, starting with the ccv/cca. thanks a lot.

Ok, So I've checked the CCA with Dale's technic and it seems ok to me : it remains in place as long as I keep a finger on the nipple, and goes back in place when I release it.
Though, I didn't test the alternate method from XanderCage, because I can't access/view the CCA when engine is runing, because I've got the stock intake setup with big air hoses hiding the CCA. But, I think the first test is enough to think the CCA is OK, right ?

So I started to check some other vaccuum hoses, and I stumbled upon those which I believe are miswired too... you tell me :
the Wastegate Control and Turbo Precontrol Valves, I believe :
https://cimg1.ibsrv.net/gimg/www.rx7...74fc8d940f.jpg

Hard to see in the photo above, so here's a quick sketch of my actual (wrong) wiring :
https://cimg4.ibsrv.net/gimg/www.rx7...ddd4e40539.jpg
On the turbo precontrol, the 2 upper/bottom hoses are inverted (A / B) but I don't know how important it is to respect the right plugging. And on the small cylinder ( 3/4 ) too, but here I think it makes no difference.
I guess it's better to replace them all correctly anyway :)

Yeah, those do look to be plugged in wrong. The input to the solenoids (which is the "log" on the back side) doesn't matter which nipple, but the 2 front nipples do matter. Also which nipple goes to which solenoid port does make a difference. Regardless, it's a good idea to hook them up properly per the vacuum diagram, that also helps with troubleshooting when things match the diagram exactly.

Those are the wastegate/precontrol solenoids, basically the factory boost control.

Dale

thanks Dale !
When I wanted to rewire them correctly, one nipple broke... I've found out it's apparently common, so I decided to glue it back and put some epoxy so I can try it before the new one I've ordered arrives.
https://cimg9.ibsrv.net/gimg/www.rx7...79f4825cc3.jpg


When remounting the UIM, I've noticed another error with the 3 small hoses that plug un der the UIM near the throttle cable. All the 3 hoses were miswired... No idea if it makes a difference, but I rewired them following the official diagram :
https://cimg7.ibsrv.net/gimg/www.rx7...960617fe0e.jpg

So, I was almost done when one intake elbow nut broke and jumped somewhere in the engine bay... I guess I gotta search for it and change the nut before I try how the car works now :)

Those 3 hoses don't matter, they all go to the plenum in the UIM. I typically just attach them however is easiest and where the hoses just want to go. But, again, for troubleshooting purposes it is nice to have it hooked up just like the diagram so you can be certain each hose is plumbed in properly.

Dale

Thanks Dave, I've put those 3 hoses back in place, so it will be easier to troubleshoot next time.

I've been able to testdrive it today,
when I started the engine it was pretty bad : engine shaking a lot (shaking the whole car) and a huge smoke coming out of the catback, I was pretty astonished becaused I took care to double check everything twice.
But it wasn't long before I figure out there was the small hose under the MAP sensor that was unplugged. (Probably happened when I removed/remount the UIM) So I plugged it back in place, and voilà ! But wow, I didn't know the MAP sensor was so important, even at idle.

Anyway, I still have the second turbo issue (leak), the pressure is definitely not enough when the second turbo comes in : (pardon my poor english^^)
I've got the 0,7b/10psi on first turbo. Near 4500rpm I've got the drop to approx 0,3b/4,5psi then a small bump to 0,4b/6psi and it stays there until redline (I guess, but since I'm still breaking in, I don't go that high)
I think I should check if my Charge Relief Valve is correctly working. (As well as the CCA with the FSM method)
I've also found some good readings on this page "Turbo / Boost Problem Troubleshooting"
so I'll troubleshoot this asap.

The MAP sensor is one of the primary inputs for the ECU. The car will run REALLY poorly with the MAP sensor vacuum hose disconnected. This is also why it's worth having a good silicone hose for the MAP sensor that's snug and doesn't want to come off when you don't want it.

Keep chipping away at this. You've definitely got a problem with the secondary turbo coming online, I would focus next on the turbo control actuator.

Dale

Alright, I've tested the Charge Control Actuator followinf the FSM instructions (with a vacuum pump) and it's working perfectly.
I've also tested the Charge Relief Valve : it's OK too.
I've barely checked (just took some pictures) the hose going to the Turbo Control Actuator (the one known to commonly crack) and it seems ok (see photo below).
But I need to check this actuator for real as soon as I can (when I get back my jack)
https://cimg6.ibsrv.net/gimg/www.rx7...bc821e3ff7.jpg
And after stumbling upon this video , I'll check if my pressure chamber doesn't leak too

Also, if XanderCage's theory above were correct (the Charge Control Actuator getting a constant vacuum), could a faulty solenoid be the cause ?

After a long time looking for this 2nd turbo pressure drop problem, I finally found the cause.

I checked many valves, hoses etc and everything were looking ok. At some point, I installed a gopro to look at the turbo control and precontrol actuators while driving. The turbo control moved normally, but the the precontrol didn't move at all. (Unfortunately I couldn't see the Wastegate actuator on this video). So I double checked all the precontrol/WG lines and actuators, and they looked all just fine... The only doubt I had at this point were the 2 solenoids' plugs... I always kept them in the same order as they were when I got back the car after the rebuild, but I couldn't verify if they were mismatched or not because the white dots on the WG one have disappeared. After reading a couple topics on this subject, it corresponded to my problems, so I switched the 2 plugs and went for a test drive... And YES !! It's now boosting just fine at 10psi until redline. Wow, it's so good to enjoy a working FD finally 😄 So, these plugs were simply mismatched by my crappy mechanic... It took 10 seconds to fix, but almost 10month to find the reason...
anyway , now time has come to enjoy the car, I just wanted to thank all the people who helped me here, and let know the solution if someone else encounters a similar problem.