I have an 83 rx7 that I purchased two years ago from a field in Wyoming. It had been sitting for four years before purchased. I did all the normal procedures for getting it going again and it worked. I have since put 13k miles on it and it has been running great. The only thing I have not been able to figure out is the very lumpy idle. It seems to jump between 600 and 750 rpms. It also has a slight stumble at 2000 rpm.

Today I was coasting to a stoplight when the engine died. My heart sank as memories of my first car's departure coasting to a stoplight came to mind. I restarted the car and it idled smoothly at 700 rpm. The hesitation at 2000 rpm was also gone. It feels like it has slightly more power and is smoother. I have started it three more times and it idles perfectly at 700 rpm every time.

Any clues what might have fixed itself? I should note that all routine maintenance has been done routinely including plugs, wires, cap, rotor, fuel filter, and oil changes. Thanks to anyone who has any ideas.

 

maybe you finally unstuck a seal?

 

Have you run any Seafoam through the gas tank yet? Might be a good idea, especially since she was sitting for so long... A couple of good redline runs each day could also help.

As to why this happened, I'd say Whitey hit the nail on the head.



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Thanks guys. I figured somebody would know. I have been running one can of seafoam in a tank after every oil change. Maybe I should run a more concentrated dose when I get low on fuel next time. Thanks for the quick responses.

 

Maybe a chunk finally blew out of a jet?