Purchased an 83... with a new motor... 40,000 on it... most modifications done where for road racing in terms of suspension... cooling etc... but the car has and does idle rough... under pressure it is fine... but idle its rough and "coasting" (manual) it seems to hesitate... also if idling and you close off shutter valve the idle picks up and is not rough but it does seem to miss...
i believe the shutter valve is bad but could that be responsible for all this?
finally... i bought some B-12 (a carb cleaner) you add it to the gas but you can't use it on a diesel... I was just about to put it in... when i started to worry if I could add it to the gas in a rotary... it works in a V8... but i was unsure? any help would be greatly appreciated...

 

any advice will still help... it also smells as if it is running really rich where is the air fuel mix screw on a 83... bottom driver side?
read other search results but still trying...

 

Get a Weber, Port the Motor...You know you want to

 

LOL, simply put.

 

-I'm sure that's just the help he really needed, guys.
Certainly the type of help I expect to see here.

I don't know if the shuttervalve is causing your problem, but Rx7Carl would either know, or know someone who will know. Click on his name in my sig.
Otherwise do a search on the shutter valve to see if others have had the same experience.

I do carb work, but I admit to not knowing all the effects of the extranious emissions control **** going wrong. It's never stayed on any of my Rx-7s for very long.

 

Just for some perspective, you might think about ignition, too. I found that the conections to the coil wires were corroded enough to make my car run crappy. With that fixed, my car idles a little less crappy. One of these days, I will get tired of it enough to clean out the carb.

 

I believe if you capped the shutter valve (the big tube) and it affects the idle, then the shutter valve is shot... (I believe that at idle the shutter valve is not supposed to suck/blow air). To be safe, go ahead and cap the valve (there are two openings)--Mazda should not have designed that stupid thing...

As for carb cleaner, use MMO (Marval Mystery Oil). Pour some down the carb (but have someone giving gas so it doesn't choke your car) and add some MMO into the tank (about a cup a tankful). You should prolly also add some into your oil the next time you chang it. Many "fuel line cleaners" or "carb cleaners" have harsh chemicals that damage rubbers or other sensitive materials. It is best to stay away from these in a rotary (as they were not intended to be used in a rotary).

Coasting and hesitating? Do you mean that when coasting, the car kind of jerks back and forth a little? Or do you mean that when you stomp on the pedal it kind of stalls for a second?

Hope this may help...
FS

 

Sounds like an inefficient exhaust/intake to me. At least I'm pretty sure that's the problem with mine, and I've occasionally dealt with these symptoms. It's worth a check.

 

OK.... check coil.... add MMO not B-12.... close shutter (nave to find 2nd opening)...
as for the shuttter when coasting the car jerks back and forth a little
finally if I take out the rats nest... and cut the cat out will the car run better for the most part???
it seems like everyone here thinks so...