Hi all, I have a few questions about my FD that maybe the forum can help me out with. I have a stutter when the secondary turbo wants to get going, which is what prompted me to open the hood and do some real investigating. It's a lightly modified '93 that I bought back around March and I'm doing work on it before I send it in for paint.

First of all, I took a look at the different actuators on the turbos. (pictured: upper and middle actuator arms from underneath the car)

The upper and lower actuators (of the three) work when I move the arms with a pair of pliers, but the middle actuator doesn't budge and looks like it's stuck open. Is that actuator operated by vacuum and not pressure? And shouldn't it move under hand power like the other two? I tried moving it in both directions, but it didn't yield. I did some research and the pressure from the wastegate on the primary might not be getting to the secondary (or maybe the secondary wastegate is stuck open? *gasp*), or a control solenoid might be bad, etc. I wanted to know if the actuator I have pictured is normal.

Now the more minor things. I took a look at my cruise control since it doesn't work (not that any of my vehicles have a working cruise control) and I found this:

I couldn't find a place to plug this into and I don't know if the plug even exists anymore. There's an aftermarket harness of some kind in the area of the plug and I don't know if it replaced or got rid of the socket this should go into. I assume it's for cruise control, though I don't know that either. Hopefully the picture shows the location on the harness clearly enough. The boost guage pressure line wanted to get in the way.

And finally, this:

It's pretty self-explanitory. Where is it supposed to go?

Thanks again for any help. I have two FC's that I know intimately and I'm just getting my feet wet in the complicated world of FD's.

 

In the first picture that actuator is for the wastegate, it will move if you give it a good tug, but it is operated by vacuum.

In the second pic that looks like the plug for the cruise control, but I'm probably wrong about that.

In the third that doesn't go anywhere, plug it and you should be just fine.

 

Thanks for your reply. I'll see if I can get a better angle on the actuator arm to get it to budge. Good to know about the air box outlet, and the cruise control issue isn't a big deal.

Sometimes the secondary spools up and stutters real bad, or sometimes it doesn't feel like it spools at all. The stutter happens at WOT, and it doesn't normally spool when I'm being more ginger with the gas pedal. The engine is already warm when I open it up, and the primary is working as it should. It feels like something is sticking open or closed. Could the actuator I was asking about have something to do with that? And is the only solution for that kind of problem a simple replacement?

Edit: I should add that the car was garaged from late June to late October.

 

Lets hope your turbo isnt on its way out..

 

If I were you I would pull the outlet off of the secondary and check for shaft play if only to make sure that the secondary isn't on its way to dying. Looking back that actuator is for the precontrol which means I need to pay better attention and that could be causing the issues you are seeing with your secondary. Personally I'd pull the pipe off the secondary to the the compressor and check for shaft play just to be safe. If you have any issues with testing check the FSM in the 3rd Gen FAQ because that has all of the testing procedures.

 

I'll pull the pipe off and check for play when I can get the car off the ground again and break lose the actuator arm in question. I'll browse the FSM in the meantime to get an idea of what to look for. Thanks again for your help!

 

*If you're still on the stock ECU, a little hesitation at transition (~3800-4200 rpm) is almost universal. It can be helped if you stay out of boost until the car is at full operating temperature, and making sure your grounds are clean (and sometimes adding supplemental grounds). But I didn't get completely rid of it until moving to a PFC. If that's not the case for you, this site might help you understand the system a little better.... Mazda RX-7 3rd Gen Stuff

*That is the plug that connects to the Cruise Control actuator. This is the part that operates the cable that goes to the throttle-body. You can see mine (happens to be chromed) in the upper right....


*That is a vent port from the airbox. It's needed since in stock form, the blow-off valve vents to the box. It typically has a "hose to nowhere" that drops down and simply vents underneath the airbox. I don't see any immediate harm in leaving it open like you have it, other that it might be a little noisy and susceptible to allowing dirt and moisture this way. They may not want to sell JUST the hose, but you could try to post a "WANT TO BUY" in the Parts for Sale section. Regardless....I would NOT plug it unless you're venting boost to an aftermarket BOV.
You could also post a WANT TO BUY for a CC actuator too, they're typically available for little more than shipping. I might even have one but probably wouldn't be able to check until after the holidays.

 

Good info to know. I'm running on a stock ECU, but the stutter I'm experiencing is different from the hesitation I might feel with a cold engine. Imagine the sound a jet engine might make when a bird flies into it when the secondary would normally start spooling.

I went to a local cars and coffee meet today and somebody there had an FD with a big turbo setup. He said he'd be willing to give me some of his stock parts to figure out my problem, so I told him I'd be asking for a precontrol actuator if I can't get it to move. Maybe I can convince him to part with a turbo if mine is on its way out.

Based on your picture (of a remarkably clean engine bay), it looks like I'm missing some equipment. Is that chrome plate with the whistle-shaped device the cruise control actuator you're talking about? Does it just consist of the plug socket, actuator, support bracket, and cable if I wanted to reinstall it in the car? It sure would be nice to have when I drive back across the country.

 

The actuator is the whole assembly...fastened with 10mm bolts into holes already present on the car. Two of those you can see in the picture. It includes that "whistle-shaped" piece, which is just a plastic cover of sorts. My car is an R1, which didn't come with cruise. I added it some years ago and picked up that chromed actuator from one of the mods here. When you get one, it'll be apparent how it bolts up.
If your car is a Touring/PEP model, it had CC at one time. There should already be buttons on the steering wheel, an on/off button on the dash and a control module behind the driver's side kick-panel. Just plug and play. Piece of cake.

 

Good deal! Thanks for the help!

 

Regarding the actuator, the middle and top ones operate on pressure. These are the boost control actuators. It's the pressure from boost that forces them open, and as they open they vent excess boost.

I would pull the little e-clip from that actuator rod end and try moving the actuator and the lever arm separately. The arm should swing back and forth readily. The actuator spring is pretty tough but should move out if you pull on it.

My stock airbox has been missing that extra hose for a long time and I don't believe there is any reason to reattach it.

David