Ok, turns out my shutter valve is bad. I was checking it because a Mazda mechanic told me that if your car doesn't hold idle with the A/C on, it's like the valve.

So I took the big shutter valve hose off, cut it in half and filled the ends with JB weld.

She idles perfect now, no more lobing. When I click the A/C on, she idles up to 1000 rpm's perfectly smooth. (Also replaced the idle compensation mushroom with another one since the old one was sticky).

So, for now, I can't afford a new shutter valve so I am going to run with the plugged hoses.

Here's the differences:

Backfires - Gone

Hesitiation - Gone

Fluctuation in cruise/idle/mixture ratio (have lambda sensor) - Gone

Fear of taking a date out in my 7 - Gone

 

Haha right on, now to resume your regular dating schedual!

...

Whats a shutter valve? is that a 12a thing?

 

the shutter valve kills the rear rotor upon deceleration to aid emissions and reduce fuel consumption.

it also sucks ***

 

Anyone know if the shutter valve is specific to a carburated rotary? I mean, I guess that would limit them to just 12a's, but you can always put injection on one....

Just curious.

 

Ya it's specific to carbureted. The FI's can turn the 2nd set of injectors on and off at will so they don't need it.

So we'll see how my mileage is now. I don't know why they felt the need for that shutter valve. When I let up on the gas my primaries close anyways reducing airflow and hence Bernoulli's vacuum. Oh well, I am sure their was a reason why, just can't seem to find it

 

When the shutter valve died on the 83 I put a plug in the appropriate hole in the aircleaner well. It solved the problem, but I think my gas mileage dropped noticeably.

B

 

Make sure there is no way for that plug to pop out and go down the carb.

I plugged mine and my gas mileage stayed the same. I'll bet your MPG problem is related to something else.

--Bob

 

I used a special plug I scrounged at the junkyard that has a protruding flange to keep it in place.

Maybe I have some fuel problems with the 83. Now, when I start it there is about 10 secs of stumbling like it's starved before it runs smoothly: hot or cold. Could it be a vacuum line problem? I don't think it's an ignition problem. So far it's just a minor annoyance.

B