The car is idling funny and I am trying to replace one part at a time to figure out what is causing this Shutter valve is there another name for this can't seem to find it in any of the auto parts stores

 

butterfly valve

Go to mazdatrix. They sell it, it'll cost an arm and a leg, but it'll work.

Also, why replace it? You'll be fine if you just remove it all together. All engines pre-82 didn't have them to my knowledge.

 

All carbureted converter cars had the shutter valve. This means '81-85 12A.

You don't want to remove everything, because the butterfly is actually necessary for proper flow in the intake port. (Removing it alters the port volume and area drastically, in a bad way) if you had to you could just disable the hoses, or (pain in the *** way) remove the unit and wire the butterfly open.

 

Easiest way is to just gut the emissions if you're exempt.

The sig will show you how...

 

I just plugged the hole in the bottom of the air cleaner: works good. I worry tho, that it may have decreased my gas mileage.

B

 

I took my shutter valve out and it definately stopped my engine from shuttering when idling.

 

I did that to an FB I had a while back but eventually it got bad again. I just bought the valve and replaced it. It worked swell from then on.

 

Easiest way to introduce a host of other problems, you mean.

 

I am looking in to possible shutter valve problems. By disabling the hoses, do you simply mean pulling the hose of the shutter valve and seeing if there is suction from this hose? If the hose is pulled off, should the valve close and no suction from small holes in air cleaner? If so, if the small air cleaner holes are plugged, shouldn't that do the same thing? many THANKS

 

Peejay's right, removing the shutter valve entirely changes the cross sectional diameter of that port runner. This causes an imbalance between it and the front one. You either leave the shutter valve in and locked in the open position or port the other runner, which takes a flow bench to get right.

 

I don't quite understand this. I know that the area around and just below the butterfly is of a larger diameter, however it narrows below that to the same size as the front rotors runner. So in reality it should flow no more than the front runner. You could remove the butterfly and bore out the other runner to the same size. I plan to try this with my current mani, but I will also be grabbing a junkyard one soon, incase it doesn't work out I'll have one thats just fine I can throw back on.

 

SHUTTER VALVE. My experience with this: RX-7 (1982) would not go over 45-50 mph. The whole prolbem started when it started dying at stop signs, but would start up right away again. Loss of power. ANYWAYS - finally removed carburetor. The butterfly valve was stuck closed under the carburetor - SHUTTER VALVE was stuck. Large hole (hose up to air cleaner) that is on shutter valve was crusty and full of crude inside hose. I considered removing shutter valve, but gently nudged it open and gently worked shutter valve back and forth and disconnected shutter vavle HOSE for now. I left shutter valve and butterfly valve intact and connected. Put carburetor back on and drove car....problem solved. I believe the closed valve actually had the car running on one rotor, RIGHT? THANKS