Ok large vacuum line on the left/ driver side of carb. that runs from a diaphragm on the lowest plate befor the intake manifold to the breather housing. Some one plugged it with a bolt. I pull the bolt and get a very erratic idle and a large amount of vacuum is present there. Is this a good sine I need to replace that diaphragm on the lower plate. It looks like it controls the butterfly. I have tried to get that butterfly to move via the vacuum and no movement. Any ideas would be great as I can't seam to find information on this part in the car. AllData systems really sucks when it comes to first gen RX7's.

 

Are you talking about the Shutter Valve? Autozone actually has some very good images of the emission control systems on their Web site.

You will need to login/create login to AutoZone | Auto Parts & Accessories | Repair Guides & More, select your vehicle and store location, then click on the links for Repair Help, follow the path for the desired guide image.... in this case the path would look like DRIVEABILITY & EMISSIONS CONTROLS / VACUUM DIAGRAMS.

If that looks like the device you are calling the butterfly (flap under carb) do a search for Shutter Valve for some great troubleshooting info. I had to replace mine and found all the details on the form.

 

I have a Spain engine and carb set up its just removing the entire carb that I dread. Plus I don't have a lot of time on my hands, so taking the carb off and fixing this possibly bad diaphragm is just a pain in the butt.

 

Yeah, removing those nuts from the base are a pain unless you have the correct wrenches. I bent a couple cheap auto wrenches to look like the OEM tool and even with those it was a pain and it took several hours. I would not want to do that job again.

 

What is a Spain engine?

The carb comes off easily with a 12mm wrench.

If it's the shutter valve you can knead a little ball of Quik Steel and keep it permanently open. Even with the carb on, I'd say.

 

YA bend the box end of the wrench 1" beack from the circle about 25 degrees. That is completely necessary to remove the driver side rear nut, the driver front comes off with a 12mm with swivel and atleast a 6" extension, the passenger front comes off easy with a short 12mm box, and to get at the passenger rear requires you remove the #2 afterburner (then it comes off easy. You will need to disconnect the oil metering pump rod from the front of the carb. Then you will need to remove throttle/choke cable. At that point the carb will lift away easily.

Practice that procedure, and you will be able to remove/reinstall it in about 15 minutes. Then you can remove your intake to remove and properly seal up that shutter valve. You will be much more happy with the results. Or you do like I did and seal up your intake barrels all around with batting (tissue). Then remove the two securing screws with precision, if anything falls into the motor your in a bad spot. Then seal up the shutter valve holes, fill both voids with RTV sealant. Then clean any debris as best as possible from batting, then use a powerful shop vac to suck the batting, and any metal filings out of the barrels. Then reinstall carb.

That shouldn't take you long, and it is a good way for you to learn about your car

 

Sorry Spare engine LoL my iPod likes to auto type for me sometimes.

 

I would imagine that the shutter valve can be wired or twist tied in the open position for a less permanent change. I seriously considered doing what alfajeffrey suggests, but when I replaced mine I had 81000 original miles on the car and I wanted to keep everything factory as long as parts are available. Also, from what I've heard the gas mileage is reduced a couple MPG without the shutter valve. Since my RX-7 gets better mileage than my 3 liter Ranger I wanted to keep it that way.

 

Yes, it appears so. A wire or small zip tie around the shutter valve lever looped over the vacuum tube closest the mixture screw would probably work.
The shutter valve lever when pulled towards the rear of the car closes the valve. When pulled toward the front Of the car it closes the shutter valve 2/3 - 3/4 approximately. It would behoove one to Examine its action before so doing. Otherwise less than optimal flow could result.

 

The shutter valve closes for a short time when you let off the gas. It blocks the intake to the rear rotor. No need to wire it. If you aren't going to fix it (I wouldn't) put the bolt back in the large hose and leave the small hose connected. Many FBs have lost the shutter valve diaphragm and it was blocked off with a bolt. Cheap simple fix. Doesn't hurt the engine. Not going to effect gas mileage significantly. If you need to pass emissions test you might need to fix it. Florida doesn't test so I have no direct experience, but I doubt it will make much difference.


OPEN


CLOSED

 

Have you found the service manuals online?
Foxed.ca - Mazda RX-7 Manuals

Here is the page for the shutter valve.

 

It's stuck closed. Do I want it stuck open then?

 

Only if you want mo' powah!

 

I'm surprised it's stuck closed. It only closed when vacuum is supplied. You do want it open. Make sure the rod in the diaphragm is fully extended and the valve will be open.

 

I will get to that as soon as I get the new clutch kit installed. Just got the starter out and all but 2 bolts out on the trani. And about to lift the engine up and forward to get the old one out.

 

So I have the clutch kit in and working on the body repairs. Found that the emissions butterfly is stuck open. I had a chance to put my fiberoptic scope down its carb and found it to be open. I think it still needs tuning though I have to always start it with the choke on.

 

Nothing wrong with that. Factory starting procedure is start the car and set engine rpm to 2000 with the choke ****. I only set it to 1500 or so. Choke **** should automatically pop back in when the needle on the temperature gauge reads around 1/4.

 

Sounds like mine so I guess its ok then. I still get a fuel smell when sitting idle after driving for awhile.