13brv3

Sounds strange, but I'm actually happy to find out that my car isn't running at full power. I just bought it about a month ago, and was a bit disappointed at the lack of power at higher rpms. It's a completely stock R1 BTW.

I finally got my boost gauge installed yesterday, and wasn't surprised to find the following:

-3rd gear, WOT, 10 psi immediately below 4500. At 4500 it drops immediately to 5 psi. From there to redline, it slowly goes down to about 2 psi. There is no noise, such as boost being blown out, and I don't hear the turbos at all.

-I also noticed that if I start from first gear, shifting at 7k, and run all the way through 3rd, I never see anything over 2-3 psi on the gauge.

Obviously, my secondary turbo isn't playing nice, so now I get to try to figure out why. The hoses look to be in pretty good shape, but if I have to pull the UIM to check the solenoids, then I'll probably just plan on doing a hose job while I'm there. So let's see, I need a mityvac, some viton hose, some gaskets...

This post wasn't really a plea for help, but if anyone knows any quick, routine failure items that will cause this behavior, I'd love to hear it.

Cheers,

P'cola FD

It sounds CRV related. If it isn't getting any pressure, then the secondary turbo will blow all it's boost out of the CRV. You can go to this link for some more info. https://www.rx7club.com/forum/showth...threadid=98645

mblachford

You dont happen to be blowing any oil at startup do you? exessive amounts could indicate your turbos going bad...

Mahjik

iTrader: (1)

Sounds like one of the vacuum lines on the firewall side of the UIM. I had the same problem.

I had removed my UIM to fix some other problems, but upon reinstallation the vacuum lines on the firewall side were extremely short. I was unable to get them on good enough when I reinstalled the UIM.

I had the same problem, the boost would shoot up to normal PSI, then fall all the way down to nothing. I replaced those two lines with ones just a little longer to make the installation easier and the problem was gone.

13brv3

I've only seen a small puff of smoke once on startup, but there is a pretty significant oil leak externally. When I bought the car, the original owner told me about the leak, and that her local dealer said it was coming from the secondary turbo. Recently though, I had to take the car to a dealer to have the ECU replaced as a recall, and they said the oil was coming from a motor mount bolt that goes through the oil pan. I'm not familiar with the mounts on the FD engine, and I haven't been able to get under the car well enough to take a good look myself. One of today's tasks is to try to find some decent ramps.

BTW Danny, if you keep being the turbo expert, you're going to get that tour of the plane soon

Cheers,

13brv3

Thanks Mahjik, I'll take a look for those too.

spooledUP7

Sounds like you have it covered. I'm not sure if P'cola FD's covers the turbo control solenoid (vacuum side) or not, but I figure I would chime that in anyway. Pull it off the ACV and test it cold and warm with an ohm meter. You should see 300ohms either way, but if not, replace the sucker. You may want to NOT remount it on the ACV since the ACV is a big heat sink.

13brv3

OK, you lost me. I just looked at a few diagrams, and consulted the list of abbreviations, and I don't see ACV. Can you give me a hint what this is? Sorry for having to ask.

Thanks,

spooledUP7

Air Control Valve. It mounts to the lower intake manifold under the Upper intake manifold. The turbo control solenoid mounts on top of the ACV.

13brv3

Got it, thanks. I was looking at the drawing on F-84 for the turbo system, and I don't see it there, but it is on the nice color vacuum routing chart.

Rusty

13brv3

I started poking around, and checking the hoses I can get to, and I found a hose that was loose. It goes to the plastic inlet pipe on the primary turbo. It attaches to a plastic tube that seems to have been glued to the inlet pipe at one time. Unfortunately, the glue isn't holding now, and the whole "fitting" is able to move around in the inlet pipe. I doubt this has anything to do with my problem, but can anyone tell me what this hose does? It's the one with the red dots in the picture.

Thanks,

13brv3

Hi again,

Well, it's been a day of discovery for me. At least I now know that most of the major parts look like. I even think I'm starting to understand how it works, so if you don't mind, how about checking my logic? I'll list the things that need to work for the secondary to produce boost, and give any comments I have as to whether they are working.

- Charge control valve. I'm assuming that this is working, since my boost drops from 10 to 5 at 4500. I can't see how that would happen unless this valve was opening.

- Charge relief valve. I've tested the operation of the valve using a vacuum pump, and it works fine. I have not checked it's function on the running engine yet, though I can T into the vacuum line with a long hose to check it. I supposed I could also disconnect the vacuum hose, and give it a test to see if the boost still goes away at 4500. This is still a suspect.

- Precontrol actuator. The way I understand this, if it was bad, I would still get secondary boost, but there would be a lag. I'm guessing that boost would be coming up, and not still going down at 7,000 rpm in third. If that's true, this isn't my immediate problem.

- Turo control actuator. From what I've read, this needs vacuum, and pressure to work properly, which is to say quickly. According to what I've read, it would still work with one or the other, but not immediately like it's supposed to. Since the boost never comes up, it's hard to believe this could be bad.

Sounds pretty simple, it has to be the CRV like Danny said

Thanks for enduring my rambling.

P'cola FD

You've got it almost all right. The boost dropping at 4,500 rpms is because the turbo control actuator is opening, splitting up the exhaust gasses between the two turbos. The CCV just keeps the boost from the secondary isolated during prespool. Other than that, you're right on target.

13brv3

I thought that was what I said. At least it was what I meant

I was just searching around, and found some posts about venting the CRV to atmosphere rather than into the air box. I may try that first, to see if I can hear it venting. If I still hear it after 4500, then I know it isn't closing.

Of course none of this is anything more than delaying the inevitable- pulling the UIM to actually fix the problem. Oh well, it helps me understand how it works.

Thanks again,

13brv3

Hi again,

I did some more testing today, and I learned a few things. I've probably also generated a wanted poster for myself on the local streets

I read a few threads that said you could easily hear the CRV if you removed the hose from the airbox. Well, I did that, and hearn nothing. That leaves me wondering if it wasn't venting, or if you just can't really hear it.

Next, I put a T in the line that goes to the CRV, and ran it to a gauge inside the car. This gives 0 psi of pressure below 4500, and 6 psi of pressure above 4500. It also shows about 2 psi of vacuum when you shut the car off. As far as I can tell, the CRV looks like it's always closed.

Finally, I put a T on the nipple on the secondary side of the y-pipe. Now, doing the normal 3rd gear pull from 3000 rpm up, I get the following- below 4500, boost is at 10 psi, and the y-pipe secondary is at 2-3 psi just before 4500. At 4500, boost drops to 5 psi, and the y-pipe secondary jumps up to about 6 psi. By 7000 rpm, the boost is about 2 psi, but the y-pipe secondary is still around 6 psi.

A couple times during the drive, I noticed 10 psi of pressure on the y-pipe secondary nipple, and eventually figured out that you can cause this to happen by running WOT above 4500, then get off the throttle, then back on again. At that point, the boost stays low (under 5 psi) but the y-pipe secondary goes up to 10 psi. I can't exactly explain this.

I know that the vacuum chamber and pressure chamber are holding to some extent for hous after the motor is shut off, but I havent tried to measure the pressures.

This all leaves me thinking that the turbo control actuator is not.. well, actuating. I checked to make sure that I had the clip on it, since I read that some folks found their control rod disconnected. I really wish I could rig up some sort of camera to see if that thing is pulling in.

Open to any other suggestions, including non-sequential

Thanks,

13brv3

Well, I just ordered a Hose Technique kit, so I guess I'll have to dive into the rats nest unless anyone has any further suggestions. I will be pretty surprised if I find a leaking hose, but I do expect to find a bad solenoid. I'd really like to defer this hose job till a few months from now, but if I have to take off the UIM, I'll just do it now.

Sigh...

maxpesce

Sounds like the CRV (that vents secondary boost<4500rpm) is working properly But the CCV (in the Y pipe to seperate Pri from Sec Turbo <4500rpm) is not opening to allow flow from the Sec. Turbo to enter the Y pipe.

Toadman

You vent the BOV to the atmosphere, not the CRV. The BOV is the brown valve closest to the airbox. Be sure to plug the airbox hole.

13brv3

At the time that I saw 10 psi on the secondary side of the y-pipe, I assumed that the CCV was must have been closed, since my actual boost was still low. It seems like I read that there is some sort of condition that causes the boost to be disabled until you get below a certain rpm again??? I assumed this must have been one fo those disabling conditions. I know that the CCV is opening during the normal 3rd gear test, because my boost drops from 10 to 5 at transition.

Thanks for the comments.

13brv3

Are you saying that this is the valve that people vent and expect to hear, or will this do something for me as a test of my boost problem? I know the BOV can't be stuck open, since I make 10 psi of boost before 4500.

Thanks,

13brv3

Greetings again,

Well, I figured it was time to go ahead and start taking off the UIM to do the hose job, and I'm glad I did. I had thought these hoses were not original, but now I'm sure they are. There are marks on the hoses where the dealer removed and replaced them during the engine swap. The owner was under the impression that they were replaced, but I don't think so now. They are also very hard, and loose fitting. No doubt there were some leaks, even on the "good" connections.

The real find is seen in the attached picture. There was a hose completely off it's nipple, and this hose goes to....are you ready... the charge control solenoid. I'm still a little confused about how this can make complete sense, but it must be the problem.

I do have a few questions still.

Do you have to remove the air control valve to get the rats nest out? If so, I sure hope there isn't a nut on the bottom side of the air control valve, because I don't see how you could get to it with the rats nest in place.

As for the solenoids- SpooledUP7, did you really mean that the turbo control solenoid should read 300 ohms? It reads 33, and a couple others that I checked read about the same.

2nd solenoid question- just to verify, these things are 12V devices right, and the polarity doesn't matter? In other words, I can just put 12V on any of them to make them actuate for testing purposes. You can bet that I will test every solenoid, one way valve, and actuator while I have this mess apart.

Thanks again for all the info. I'll be working in New Orleans for a day or two (inspecting an MRI scanner that got flooded in the hurricane), but I hope that I'll be reporting very good news by the end of the week. Man, I can't wait to see how this car is really supposed to work. The hose job will be the 3rd "mod", following a boost gauge, and aluminum AST, so I suppose a DP will be next.

Cheers,

13brv3

Success

The boost isn't quite textbook, but it's close enough. I'm getting 10-6-10, with a fall off to about 8 at redline. Of course I didn't need the boost gauge to tell me it was working better now

Thanks to all that offered help.

13brv3

Just to continue the saga, the first post-hose drive was last night, and it was fine. I stopped and got gas, then drove back and it was still fine. Today, I went to the local auto parts store and it was fine, then stopped at the car wash to spray the oil off the bottom of the engine and subframe. When I left the car wash, I was right back to my original problem

The only two hoses I couldn't change were the ones that go to the turbo control solenoid. I was waiting until I needed to get under the car, which was today to chase my oil leak. Anway, I changed the two hoses, and they looked fine of course. Later, I took it out again, and all was well. I made a point of stopping at a convenience store to get a bottle of water. I drank the water, while I let the car sit and heat soak thinking that this may have been the key to having it not work earlier. Worked fine on the way home though.

I gotta tell ya, I don't have much confidence that this problem is gone for good. Maybe it is a solenoid that breaks down when it heats up as someone suggested earlier. All I know is I'll be looking into non-sequential before I pull all that crap out to work on it again.

kwikrx7

Although the non-seq. mod is great for simplicity (and always having reliable boost) - it might not benefit you being stock. Being stock or even close to stock you may not get full boost until 5K rpms. Usually having a full exhaust and a few other mods really compliments the non-seq setup and you can have full boost by 3500-3900 rpms - but I'd stay sequential until you're absolutely sick of boost problems - doing a full hose job can help tremendously - there is also a vacuum hose simplification diagram which eliminates around 50-60% of the vacuum lines - it's found at www.rx7turboturbo.com - something to think about.

13brv3

SpooledUP7


I had to revive this thread to tell you that you were correct about turbo control solenoid. I tested it cold when I was doing the hose job, and it was fine, but after everything was back together, I kept having intermittent problems with the secondary turbo not coming online. While replacing my coils and harness for another problem, decided to finally follow your advice to check the solenoid when hot. I put an ohm meter on the coil of the solenoid, and it read about 35 ohms. I then put a heat gun on it while watching the resistance. After just a couple minutes, the reading went from 35 to about 40, then jumped to open circuit. When it cooled, it was back to 35. I did this several times because it just amazed me. Anyway, I'll be ordering a turbo control solenoid Monday morning, and I'm pretty confident that my turbo troubles will be gone.

Thanks again, and sorry it took so long to actually try your great suggestion