gdub29e

iTrader: (16)

The sequential system operation is defined on F-84 of the workshop manual. When running down the road in vacuum, the system will have the wasegate at 95% duty or fully closed. As you start to accelerate and the turbo charger begins building pressure the pre control actuator is duty cycle driven to reach the 10 psi target. After it changes over from sequential operation to parallel the pre control remains at 5% duty and the wasegate is duty driven by the ecu to reach its 10psi target.

If you force your wasegate duty cycle to 100% or fully closed after the system chances to parallel operation it will spike pressure. What that psi will be I can not say because it is a combination of spring pressure and additional force added by the boost pressure vs the exhaust force pushing the door open. I’ve never wanted to find out what it will cap out at. I assure you it’s well past the safe operation for the Oem ecu. If you force the wasegate to 5% duty cycle or fully open, on a stock car you will see almost zero pressure anywhere. The spring pressure or “cracking” pressure of the Oem actuators is “around” seven psi. If you were to remove the hoses off of them, this is the pressure you will general's see around caused by the exhaust pressure being exerted on the wastegate door.

What I’m trying to do is guide the OP and future individuals with systematically testing the system in a process. That way in the future, the op and future individuals can solve these issues themselves so they don’t loose an exorbitant amount of time they could’ve been enjoying the car. The work shop manual is an invaluable tool that’s extremely under utilized. You can spend a ton of time jumping around guessing, or you can invest the time testing the components so you know. That way you don’t shoot yourself in the foot so to speak.

Please don’t misunderstand, that’s not a shot at you or anyone in particular. It’s exceedingly hard to troubleshoot a problem over a forum thread. These are just my opinions from experience, though I am just another guy on the internet.


~ GW

gdub29e

iTrader: (16)

ndinunz

Thanks for the responses. I arrived home last night, and was able to perform a smoke test using the video linked above. It looks like things are sealed up pretty good after replacing that coupler. Once I get some time, I’m going to go ahead and test the actuators and report back.

As a side note, the improvement in drivability after replacing that coupler is huge! So that’s at least motivating

ndinunz

I had an opportunity to dig a little more, and I tested the charge control actuator. That one is functional. I also noticed that the lines going from the turbo to both the wastegate actuator and the pre control actuator have been replaced for silicone lines. I ran out of time to actually test them or pull the lines off, but I did pinch them a bit and cannot feel anything that resembles a restrictor pill. Not sure if that would cause a low boost scenario after the transition

gdub29e

iTrader: (16)

The charge control should be closed when the car is running at idle. It’s easy to take a peek and see. It should pop open when the vacuum is removed.

93 turbos had the restrictor pills inside the hoses. The later cars had them pressed into the primary turbo nipples. If you don’t have them in the hoses, double check if they are pressed in the nipples. If you do not have pills you will need to install them. Easy way is to use carburetor jets the appropriate size. The pre control which is the longer hose size is “ .059 “ and the wasegate which is the shorter hose is “ .064 “. You can always buy new hoses from Mazda that have them already, but that’s the more expensive route.

~GW

ndinunz

Interesting, I’ll double check the nipples and make sure the hoses don’t have them before I install some.

As far as using carb jets - is the usual method to just press them into the silicone line?

scotty305

iTrader: (2)

Thanks for correcting. If the wastegate solenoid or actuator were not working, I don't think his system would see 10psi at low RPM before the transition. 10psi on the primary makes me think the wastegate and precontrol systems are likely both working correctly.

gdub29e

iTrader: (16)

Yep, just put the correct ones in their respective hoses and push them in an inch or so. But double check you don’t have them pressed into the tap first.



For sure. 10 psi on the primary is a good sign. I’m thinking it’s one a few things. Lazy turbo control door, vacuum box not holding vacuum ( which will exhibit really weird behavior because you initially have vacuum to control things and then it bleeds away) just a couple off my head.

gdub29e

iTrader: (16)

I took some time and went over this thread again from the start. I need some clarification on what you did with the “Turbo control” solenoid. Here is the statement you made.








The turbo control solenoid is three ports. The factory cap on the port facing the rear of the car is actually not a sealing cap. The factory cap allows air to vent out through a little filter to stop contaminants from re-entering. This cannot be capped with a regular vacuum cap or it will not allow the pressure from the turbo control actuator to escape during switching. You need to double check that you have not sealed this off.





A few things to do next after you test your precontrol / wasegate actuators and turbo control is to check your vacuum check valves and test that the vacuum box is in fact holding vacuum. It should hold for a long period of time. I check them with a mini vac.



~ GW

ndinunz

The very first time I pulled that solenoid out and tested it, I misunderstood the testing procedure. I also mistakenly misunderstood the filter on port C for a sealing cap. I had initially ran the car with the cap on that vacuum port, and got some strange symptoms from that. Someone in this thread pointed out to me that the cap was meant to be a filter and not a sealing cap. I later found a heat-related issue with that solenoid and have since replaced it for a brand new one with the appropriate filter on port C.

When I had the solenoid rack out most recently, I tested both the vacuum and pressure chambers and all the check valves.

One thing that I can't remember whether or not I mentioned in this thread is that I performed this "fix" or, rather, failsafe that is outlined in this thread: https://www.rx7club.com/3rd-generati...ctive-1120259/

gdub29e

iTrader: (16)

Great! One less thing to repair. I use the “fix” for a sticking E solenoid also, even though mine doesn’t stick. You’re fine as long as you have the check valves in the correct orientation.


You should be able to test the vacuum box without taking too much apart.


~ GW

ndinunz

I think I MAY have found my problem. Or at least some of them lol

1. There are definitely not restrictor pills in those lines. I took a picture of the nipples on the turbo. I can’t really tell whether or not they are integrated. It looks like they may be, but I’m not sure what it should look like:



Thankfully, I had some spare actuators with lines still attached (thanks Steve Holt). I inspected the lines, and found these inside. One looks like it may be factory. I measured them with my calipers and they seem /about/ right, kinda tough to fit the calipers in there.




2. What I think the main problem is: my turbo control actuator doesn’t seem to hold pressure. When I pump pressure onto the port outlined in the FSM, it sort of stays open if I keep pumping, and I can only apply a maximum of about 5psi (consistent with the boost number I'm getting after transition). As soon as I stop pumping, the actuator returns to position. I can also hear a hissing sound as I pump.

THANKFULLY (again thanks Steve Holt) I have a spare TCA that I bench tested and seems to behave as it should. Rod moves when I pump, and returns when I release pressure.



I also tested the wastegate and precontrol actuators, and they behave as they should. For peace of mind, I also tested the vacuum tank, and it holds 25inhg consistently.

Before I attempt this, one question for someone who may be more experienced than I. Is it possible to replace the TCA with the turbos still in the car? There looks to be minimal clearance between the subframe and the TCA but i can definitely get a tool in there. I just don’t know if the unit will actually come out. The external c clip also seems to be missing. I may have a spare, but, if not, I have a spare set of blown turbos that I can measure it off of.

gdub29e

iTrader: (16)

Your pills are pressed into the housing. You do NOT need them in the hoses. A easy way to measure a small hole like those is to find the correct size drill bit that fits nicely, then use your capers to measure the bit. You get a feel for it, almost like when you use a feeler gauge.


The turbo control actuator will cause all of the symptoms that you are experiencing. It’s blocking the exhaust flow when it’s partially open during parallel operation. You can change the turbo control in the car, I do it from the bottom. You will need a new cir clip. They are available at Mazda. There should be a white paint mark on the rod that lines up with the end of the bracket when installed. May be hard to see. I wouldn’t make any adjustments to it unless it’s missing the hardware and you have to swap yours over.


~ GW

gdub29e

iTrader: (16)

The turbo control actuator cir clip is part # 9957-50-400


~ GW

ndinunz

Thanks for pointing all of that out and providing the part number for the clip. Nice to know that the pills are pressed into the nipples.

I didn’t even consider the adjustment not being the same. I believe I’m missing the bracket that goes with this TCA, but I’ll check my parts stash and also inspect the rod for a paint mark. Any pointers on adjusting it if need be?

gdub29e

iTrader: (16)

No worries, happy to help get you sorted.

Change the mounting bracket over from your current one to the new one and get it all installed. Then check for the paint mark. Generally, the adjustments are so close you won’t need to make any tweaks. We will cross that bridge, if it comes to it. For now, just get it all sorted and go test the car.


~ GW


P. S. ~ when you remove the turbo control actuator from the mount, sometimes there’s shims underneath it. Make sure you reinstall those.

ndinunz

Got it! I'll report back once I test the car.

ndinunz

I just got around to swapping over the TCA and testing the car. I’m stumped. Exact same symptoms, zero change in performance whatsoever.

A couple notes: the TCA that I removed from the car did not have any shims, but the spare had some. I put the shims on even though I used the existing bracket on the car. I didn’t see any paint marks on the rod, but I left the adjustment as is. I also bench tested both the spare TCA before installing and the old one I removed. Spare passed the test, old one definitely leaked on the bench test.

So just to recap:

• Working charge control, pre control, wastegate and turbo control actuators
• Working charge relief valve
• Pressure and vacuum tank seal
• Working check valves
• Intake system passed smoke test

Current symptoms:

• 10-3-5 boost pattern
• Holds boost after shifts
• Holds 5psi to redline (no tapering)
• Basically the same boost pressure in every gear. I’ve been doing my pulls in second, in third I notice maybe 6psi after the transition but it’s hard to tell

gdub29e

iTrader: (16)

Well that's unfortunate. But you're making progress. Sometimes this stuff becomes a process when you have more than one issue.

So this narrows it down to a few things. Charge control solenoid "F" not opening the charge control, Charge Relief solenoid "H" not closing after parallel operation takes over, This receives pressured air to force it shut. ( think massive boost leak if it doesn't) Turbo control adjustment incorrect or Turbo control "E" that's new is faulty. Blown secondary turbo ( wouldn't think so since its not smoking but I would of checked that in the beginning )..


I think if I were you I would test that the solenoid "h" was plumbed correctly and working. Or maybe even plug it for a test. When I say plug it, I mean plug the exhaust port that heads back to the air box. This will leave a bit of a hole in the pattern but if its leaking you would build pressure again after.

If that did not make improvements I would wire open the charge control and the turbo control and probably plug the charge relief to see if I could build boost at all in parallel operation.

I can walk you thru the turbo control adjustment but is a bit of a lengthy process. If it comes to that it may be easier to chat directly.


~ GW

ndinunz

Alright, I really appreciate your time and effort.

So just to clarify, first step is to basically plug the charge relief valve to see if it builds any boost during parallel operation? I’m assuming this resulting in no change at all would verify that both the CRV is functional and plumbed correctly and that the solenoid is operating properly.

gdub29e

iTrader: (16)

Correct. I think that's the next easiest thing to test without having to get more involved. You can pull the hose off and put a cork in or something to block it just to see if its staying open.


~GW

ndinunz

I just ran the car with the CRV hose going to the airbox completely blocked off. I noticed zero change in performance; true for both primary and parallel operation. I was definitely expecting primary operation to be affected at least somewhat. Not sure if this is a concern or not

ndinunz

Also a follow-up question to the next test. The default position of the charge control is open correct? (When it’s off of the car, the valve is open) I just want to clarify, when you say wire open, do you mean force it to stay open or force it closed? If forcing it to stay open is the goal, could I achieve the same result by pulling the line off of the nipple and plugging the line? It makes sense to force it open in the context of the test, but i just want to be sure.

Also, for this test, are you suggesting to wire open the turbo control, charge control and plug the charge relief all at the same time, or are these individual tests?

gdub29e

iTrader: (16)

No change as in the car still has the same pattern?

Did you make sure the Charge relief rubber hose doesn't have a hole in it ?

Yes, in the default position the charge control should be open. When the car is running it has vacuum applied to it to keep it closed. You can unplug the line from it and cap it. I meant to wire open the door on the turbo control.

What I'm suggesting is to unplug the charge control, plug the charge relief and wire open the door for the turbo control. This basically makes the car non sequential. IF this does not change anything then you have a blown secondary turbo, wasegate that's sticking open, issue with the wasgate / pre control solenoids or an issue with the wiring that feeds one of the four seq turbo control solenoids / boost control .

ndinunz

Understood. I just pulled the hose for the CRV off and saw no holes. I also pressurized the hose and it holds. Yes, that’s correct, no change in pattern with the CRV plugged.

Side note: when I pulled the line off of the nipple on the CRV that goes to the manifold, I heard a hissing noise.

I’ll try the next test and report back