this is a problem that just started today and I'm not sure how serious it is. I'm driving a 83 12a and today I had about a quarter tank of gas and a friend of mine put some octane boost in my tank to see what it would do.....anyway now my RMPs jump all over the place at idle, and the car keeps stalling. is this a serious problem???????

 

from what i've heard, high octane fuel is NOT good for a 12a. it is harder to combust than normal octane, which means it is good for turbo or high compression engines. it will probably be fine, but i think i would just stick with normal octane next time you fill up.

 

High octane fuel isn't ideal for na rotaries, but it's not gonna hurt anything either. I don't think it in and of itself would cause the problem you describe... maybe your buddy put way too much of this stuff in and it fouled up your plugs or something? It also could be completely unrelated and just a coincidence, remember you're driving an old car and things can go wrong often enough lol. I'd check the usual things for a rough idle, namely ignition. Just my 2 cents

 

Most of the time that octane boost stuff is MTBE.

MTBE also has the effect of "leaning out" the fuel.

I've heard cases of where people had to drive with the choke out all the time just to keep it from stalling, because of the high levels of MTBE that the government mandated.

Top off the tank with fuel and see if it improves any.

 

ok I found the culpret. My battery was loosing charge, I'll assumb thats why it was stalling and the RPMs were jumping

 

You beat me to it. I was just going to suggest that, the symptoms described sounded like a dying battery and not a fuel related problem.

 

ditto, octane isn't going to do that, but dropping in the foil safety seal will.

 

I've heard that it's not good to put additives in the gas tank of a rotary.

 

Except MMO

 

Or Lucas Fuel System Treatment...

Or Motomaster Formula1 Synthetic Fuel System Treatment

 

I put a can of seafoam in my tank every other time I fill up.