13brv3

The Freshmaker must still be sleeping it off :smirk:



The "restrictor pill or manual valve" means that you could have the stock restriction (pills in 93, and restriction built into the actuator later on), or you could have the Home Depot boost control valves installed. You've probably heard about these, but they're basically just needle valves that you can open and close as needed to adjust boost. It's like having a variable size pill.



If you put pressure in the line that should have the pill in it, the actuator should move. I'm not sure exactly how much pressure it takes, but 10 psi should certainly be enough I would think. The fact that it holds pressure is probably good, since it would likely mean you have no leaks inside the actuator. You asked about the possibility of a plugged pill, and that is possible. The pill is just a short, maybe 3/16" long steel cylinder that has a precision hole drilled in it. If this manages to turn around in the pipe, it could effectively close off the hose. I'd definitely look at both pills (precontrol and wastegate, which aren't the same btw), and keep in mind that you may not have pills if you have a later model actuator for some reason.



FWIW, I don't believe this is going to be your problem. The precontrol is just there to get the 2nd turbo up to speed before 4500 rpm. If it didn't work at all, you'd just see a bigger dip and longer delay for boost when you pass 4500. I'd take a closer look at P'cola's thread that he linked you to, and follow some of those tests. My money is going to be on the charge control system. It sounds like it's not opening properly.



BTW- has anyone gone through the vacuum hoses? Are you very sure they're all OK? More history might help.



Good luck,

LAracer

Thanks 13brv3. My car is a '93 so I'll check to make sure the pill is ok. As far as I know, no one has touched the hoses. I was planning on doing the hose-job (sometime this winter), but I still want to find out what this problem is first. The car has 20k original miles so I didn't really think I'd need to rush into it. (I bought a car with low miles so I wouldn't have to worry about this stuff , but I'm actually quite enjoying getting to know my car so intimately - now that I have some help)



Another reason I think the problem might be the precontrol is that I T'd into the nipple on the secondary side of the y-pipe, just behind the charge releif valve. At WOT in 3rd I saw 0psi up to 5250rpm, then it jumped very suddenly up to 7psi. This makes it look like the secondary is not getting prespooled. Might there be some other reason this happens? I had read on another thread that the pressure here should begin to rise smoothly after 3000rpm (when the precontrol opens). That made sense to me since the secondary should be prespooling and the compressed air vented to the charge relief. Sorry for not putting all this in the original post. I wanted to link to my post at RX7club, which has all the tests I did, but that site is down for some reason. Still, I think that's everything now.



I will check the turbo troubleshooting site for what to look for in the turbo control.



Thanks again.

13brv3

I also resisted the hose job, and tried to fix my problem without doing it. Silly me :redface: Of course my car had 83k miles, but when I pulled off the UIM, all was revealed. I found one hose completely off, and a couple others that were cracked. This left me with a system that worked most of the time. Eventually, I also found a bad solenoid which has left me with a system that works every time (so far).



If I were you, I'd at least take the time to take a good look without taking the UIM off. If you remove the pressure tank in front of the UIM, and get an inspection mirror, you should be able to see most of the hose connections. I'd say there's about a 50% chance you'll find one off. Take your time, and make it a very careful inspection. You might just get lucky. BTW- there is at least one pipe that you'll see near the front of the rats nest that doesn't have a hose if you have a manual transmission car. There might be two, but I can't remember. You'll also see a few plastic one-way valves that have a tendency to crack. Also look to see that the electrical plugs are connected to all the solenoids. Don't forget to look at the back side of the UIM with your mirror, since there are a few hoses back there as well.



I just have to bet that you'll either find a hose off, or a broken check valve or solenoid nipple. I can't emphasize enough how closely you'll need to inspect all this. I thought I looked carefully, but the hose that was off could easily be seen with everything together. I just didn't look close enough.



Good hunting

LAracer

Thanks again 13brv3. I have taken off the pressure chamber and the precontrol and wastegate solenoids. I see all the hoses in there, and I gave it a quick look but didn't see anything obvious. I'll take your advice and be much more systematic.



Correction to earlier post: On one of my posts above I said I presurized the hose going from the y-pipe to the precontrol actuator, and I said the actuator did not move. Well, I did the test again just now and it DID move. I must have screwed something up the first time. I am now satisfied that I understand how the precontrol works, and I am 95% sure it is working fine. I'll tap into an actuator hose the next time I go for a drive and verify it gets pressure, but right now there is alot of stuff off the car, so I'll do a thorough inspection of the hoses and check the turbo control system before I put it back together.



Thanks alot for the help you guys. I'm sure I'll have more questions before the end of the weekend...

LAracer

Well, I had a better look at the rats nest. Didn't see any cracked or popped-of hoses, but there's still alot I can't see...



I tested the check valves going to the vacuum and pressure chambers. They are ok. And there are no leeks in the pressure chamber or its hoses. Don't know about the vacuum side since I guess some of the solenoids are open, and I haven't isolated them all yet to close them off.



I'm still not 100% sure it's not the precontrol. Remember the test I mentioned earlier that I got 2.5psi on? How would that happen if the precontrol were working? Should be much higher, right? The only place for there to still be a problem with precontrol is in the signal that the solenoid receives (everything else has been tested). Maybe the connectors for the precontrol and wastegate are switched. I know I should look for the matching dots, but there is only a dot on the wastegate solenoid, not any of the connectors. The connector that is currently on the precontrol solenoid has a pinkish bit on the plastic protecting the wires. Could this tell me anything?



Even if it were the turbo control, would that explain the late transition? I still don't know what exactly causes all the solenoids to click over at 4500rpm. Does the ecu send the signal based on the rpms? Does the ecu see the same rmp signal as my tach? Might something be wrong with the ecu or the rpm signal it receives? Or is there a simpler explanation. (None of the troubleshooting lists I have read so far deal with late transition.)



Any ideas on any of this?

13brv3

It's my understanding that the ECU controls when the transition happens. I'm pretty sure you can set a different RPM with aftermarket ECUs like the Power FC. Is there any chance the original owner sent the ECU off to be modified? There are a number of companies that will modify the original ECU for bolt-on mods, but I'm not aware of any of them changing the transition point.



While on the subject of ECUs, has your car had the ECU recall? It corrected some electrical problems that caused the engine to stall sometimes when the car was under high electrical load. If you're on the list to get the upgrade, it's free, and would let you test the ECU. You'd have to give your VIN to the local Mazda dealer to let them look it up.



I had wondered about the possibility of an RPM miscommunication between the tach and ECU, but I doubt it's at all likely. Nothing is impossible though.



Back to the problem- I'd start looking now at the charge control valve when you get things back together. You may need to T into the control lines for that, to see what it's doing. That valve should be opening at 4500 RPM, and the result should be obvious on the boost gauge. I think you're going to have to just start checking every vacuum signal you can while testing the car. Keep a good written record, and see if that turns up anything. Sorry I can't be any more specific.



Cheers,

SPOautos

pull off your uim and look for some leaks and blown off hoses



STEPHEN

LAracer

13brv3: Thanks again. I've called the 800 number to find out about all the recalls, and there wasn't an ECU one. I don't think the ECU was modified. Would I be able to tell if it was?



I'll start looking at the charge control valve.

13brv3

You would think there would be a sticker or at least some writing on the outside of the ECU if it had been modified. It's probably stock as you expect.



BTW, did they say you weren't on the list for an ECU, or your car already got it? I just found the recall letter- SSP39, and the VIN range was from P0200062 to P0209530. You must have a late 93 car if you missed this range.



Cheers,

LAracer

My VIN is within that range. They said the car had required 2 recalls and both had been done. The brakes and the fuel line I think. Definitely not ecu. Maybe I'll call back and check. Thanks for the info.