r1owner

Are the rods for the turbo precontrol and wastegate
control supposed to be (able to be) moved by hand?

I just tried to move them and could not (car was off and engine was cold).

I am troubleshooting a no boost on the 2nd turbo issue and am trying to see if these actuators are working correctly.

The car boosts fine on the first turbo. When it is supposed to transistion, it makes a weird fluttering type noise and no boost. This started happening on the last run down the quarter mile a couple of weeks ago. I've checked the charge relief valve and the other valve up top, and they appear fine as does the pressure tank.

cabaynes

iTrader: (4)

hey man, it's Charlie (guy that rode with Dan)... sorry but i forget your name. anyway, i'm not sure... i still havent checked out my car cause i havent been driving it much. but i'll let you know what i find on my car soon. i should try and fix it this week... keep me updated if you figure anything out.

thanks
-Charlie

duboisr

The spring is seven lbs . My mechanic is not that strong and he said he can put a vice grip on the rod and pull real hard and move it . So it can be done but is hard . This does not say the diaphragm is still good ,that can be checked by putting air pressure on the nipple ( over 7 lbs ) to see if the rod moves .

Decay

I think this is directed at me

But yeah, I am having the same issues (only sometimes) as this thread starter. My car does it at the track too...one run it will make fine boost, but the next run the car falls flat on its face. Haven't really looked at mine much either, Charlie. Been meaning too but haven't had the time.

SleepR1

Read this site

http://www.autosportracetech.com/RX-7/rx7stuff.htm

Inspect the vacuum chamber check valve, turbo control actuator solenoid, and turbo control solenoid (it's one of the first three on the rack).

Check the c-clip on the wastegate actuator rod, and the c-clip on the turbo control actuator.

You should be able to the push the precontrol and wastegate actuator rods in, NOT pull them out. The rods' default position is out, which keeps the precontrol and wastegate doors shut.

The pressure chamber is related to primary turbo issues, not secondary.

r1owner

Yeah, I've looked at his site.

He doesn't mention the two solenoids that are in the front of the intake though. I am slowly going thru the manual to check stuff. I checked the turbo actuator tonight according to the manual and it checked out fine.

I am starting to get worried now, as I am running out of stuff to check!

SleepR1

Check the Turbo Control Actuator (TCA) solenoid. It's the one under the extension manifold next to the air control valve. This solenoid has both vacuum and pressure inlet nipples. Sometimes one of the lines will disconnect. If you're lucky that's all there is. If not you'll need to test the solenoid for its function. Testing requires a 12 V battery source, voltmeter, and vacuum/pressure pump. An easier way is to borrow a buddy's TCA solenoid that is known to work, swap the TCA solenoid out on your car, and go for a test run

cabaynes

iTrader: (4)

haha, yea sorry i got confused.. forgot your screenname on here. but it's funny how we're all having the same issues. Anyway, Dan and i should be checking mine out this week sometime so i'll make sure to bump this thead up with our findings. thanks guys

r1owner

Thanks for the info, I really appreciate it. I'm not sure where this solenoid is. Do I need to take the manifold off to get to it? Is it one of the solenoids that sits facing the front of the car? I checked all the vacuum lines going into those and they look fine.

Sorry if I'm asking too many questions, but this is my first turbocharged car. BTW, I bought a vacuum/pressure pump so I can test these things. I am learning a lot about the turbo system now.

In driving the car tonight, I am almost convinced it is a control related issue. It boost perfectly till 4500, then nothing (0 boost) except a kind of hollow fluttering noise. If it is boosting at 10 PSI on the primary, and nothing after 4500 its not likely to be a hose (under pressure) leaking is it?

I mean it can sustain 10 PSI on the primary, it should hold 10 PSI on both right? Or could the additional volume of air cause a leak under 10 PSI when the are both turning?

SleepR1

Yes

Quote:

Is it one of the solenoids that sits facing the front of the car?

No, that's the wastegate and precontrol solenoid pair.

Quote:

It boost perfectly till 4500, then nothing (0 boost) except a kind of hollow fluttering noise.

These are the symptoms most FD owners report when the TCA solenoid has either disconnected or failed.

Quote:

If it is boosting at 10 PSI on the primary, and nothing after 4500 its not likely to be a hose (under pressure) leaking is it?

There could be a number reasons for the secondary turbo not coming online at the transition rpm: charge relief solenoid, charge relief valve, air bypass valve, turbo control actuator solenoid, turbo control actuator, turbo control solenoid, vacuum chamber check valve, charge control solenoid, charge control actuator, charge control valve, oil-filled vacuum chamber, turbo precontrol actuator rod (not adjusted properly or c-clip fell out)--and this was NOT an exhaustive list

If you want to narrow your possibilities. Try this. Accelerate WOT in 3rd gear. Once you see the boost drop at transition rpm, lift off of the throttle completely, to create 20 inches Hg vacuum --then get back on WOT. If your secondary turbo comes online at that time, you're dealing with a bad vacuum chamber check valve, or oil-filled vacuum chamber.

If lifting off and getting back on WOT does not bring the second turbo online, then you've got to work through the troubleshooting process (no way around it, sadly enough).

Read the site I posted earlier--there, you'll find all the info and troubleshooting tips. The '93 Rx7 shop manual is also a great resource.

I've had turbo problems for the past year, and it's been very satisfying to solve them, and then help others with similar problems!

Good luck!

jd to rescue

iTrader: (3)

Check to see that the flange nuts are tight on your y-pipe. The nuts may be tight over the primary turbo, but not tight over the secondary turbo causing the secondary boost to escape to the atsmosphere. You may be able to tell by tugging on the y-pipe but it may still be necessary to do a visual. To do that you will need to remove the imput pipe to the secondary turbo. It lays over top of the secondary turbo outpot port and y-pipe when viewed from above.

SleepR1

How about some follow-up on this. What was the cause? What was the fix?

r1owner

Well.......I haven't had much time to work on the car to be honest. I have checked all the valves up top....charge relief, etc. They all check out fine. The pressure chamber is fine. I still need to check the vacuum chamber though.

I promise to update this thread when I get it resolved. I am hoping it is one of the solenoids under the intake. I am also contemplating replacing all the hoses while I'm doing troubleshooting this thing.

I appreciate all the help so far.

allenhah

iTrader: (4)

This might sound silly, but when I first bought my car, it had a very very similar problem...it was running too much boost up to 4500 and would fall flat. In my case, it was a simple matter of having the wg control and precontrol solenoid pairs swapped! For some reason, the two green connectors at the front of the intake were swapped.

adam c

iTrader: (2)

A friend of mine had the same problem. One of the plugs to the solenoid has a white dot on it. The corresponding solenoid has a white dot too. Those are supposed to be connected. In his case, they were switched.

r1owner

That would be nice if it was my problem. However, the car was running fine. I put on an M2 CAI and it was spiking to 15PSI for about .5 second at the transistion.

I think one too many spikes either broke a line or one of the solenoids.

r1owner

OK, I started tearing it apart tonight. Got the extension manifold off. Everything looks fine, except I was taking one of the lines off the front of the extension manifold, and I think I busted the nipple on the solenoid that it goes to (first solenoid in the rack towards the ft of the car).

I kinda hope it was already busted and causing my problem, but I doubt it. Also while doing this, I decided to hook my vacuum pump up to the vacuum chamber to test it again. It doesn't appear to be holding a vacuum. Could this be my problem? Again, the car boosts fine on the 1st till 4500, then nothing, but a sort of fluttering noise.

Looking at the location of the vacuum chamber (from the site mentioned above) reminds me that I threw an alternator belt about 1 week before all this happened. I wonder if the belt damaged the chamber?

Should I continue with this adventure, or just replace the vacuum tank and button it back up?

SleepR1

That's the double throttle control. This might be a cause, but I doubt it.

Quote:

I decided to hook my vacuum pump up to the vacuum chamber to test it again. It doesn't appear to be holding a vacuum. Could this be my problem? Again, the car boosts fine on the 1st till 4500, then nothing, but a sort of fluttering noise.

Bingo. 80% sure this is the problem. Replace this vacuum chamber. Sorry to say, this job is a royal pain in the ***

Quote:

Looking at the location of the vacuum chamber (from the site mentioned above) reminds me that I threw an alternator belt about 1 week before all this happened. I wonder if the belt damaged the chamber?

Quite possible...or it's leaking due to age?

Quote:

Should I continue with this adventure, or just replace the vacuum tank and button it back up?

Replace the double throttle control solenoid, b/c you have to (you broke the nipple), and replace the vacuum chamber. Button everyting back up. Report back to me, and let me know how things turn out! Good luck!

r1owner

Dammit!!!! I checked the vacuum chamber again today and it was fine. I just didn't realize it was that large and required more time to get the air out. It held 20" vacuum with no problem.

I guess I will check the TCA solenoid next then.

fd3s_rx7

iTrader: (13)

Had the exact same problem!
Look at your TCA hoses and check your pills. Change it to silicon hoses and clamp your pills to it. That's what I did to mine and wolla boost was perfect.

dhahlen

iTrader: (5)

Alright, so I was under my car, I unbolted the cover from the wastegate and moved the door around after i removed the arm from the solenoid. Now, there wasn't a clip holding the arm onto the handle the moves the door, but it was on there pretty good, I had to put a little force on it to tug it off. Well the door seems to be working fine. Now, my boost pattern is 13-5-6, it used to be 13-8-13, and then all the sudden it stopped working properly. I read the webpage listed above and I am trying to locate the electrical connection that controls the solenoid. I see the solenoid and it has a white dot on it, and I can see the other solenoid. All the lines are on, but I do not see where the electrical connector would connect, unless it is under the car and I am missing it. Both turbos are fine, I dont know where to look. Any info, PLEASE HELP!

Thanks

r1owner

Shoot man, my car is still down. No time to work on it, plus winter has been cold here up until lately.

I did manage to check all the other vacuum/pressure actuators. They all seem fine. So, I am down to hoping one of those solenoids are bad.

Lets say they (the solenoids) all check out fine. Is there some diagnostic tool you can use to make sure the signal is being sent to each solenoid when it should?

Heath

iTrader: (11)

I have a double throttle solenoid I will sell for $10 + shipping if you need one.
morganf1@aol.com

r1owner

Well, time for an update. I finished putting the car back together last week.

I checked all the actuators, all the check valves and all the solenoids. Every one of them checked out OK

So, I ended up doing a vacuum line replacement. I buttoned everything up and hoped for the best.

It is back to running great again! I missed this car.

I wish I could have found something definitive that was causing the problem.