Hello, this is my first post on this site. I hope I can get some help with my rx-7. I picked up a RX-7 with a 13b (unknown year) and a 4 bbl (aftermarket, forget brand.) a few weeks ago.

I have two problems that I think are related. When the engine is cold, the car will die if I let off the gas, even with the choke. When warmed up it idles just fine EXCEPT when I let off the gas at a higher RPMS. Let me expain; I'm accelerating to 4k rpm and then shift to nutral and slow to a stop. The engine with drop to 400-500 rpm and strugle for a few seconds. Sometimes it will die, other times it will recover.

One more thing, when decelerating IN GEAR from 4k or above the car will backfire. I don't know if this is related since my exhaust sounds like there is a leak. I'm replacing the entire exhaust (racing beat header, mini-presilencer, muffler and OEM connecting pipe) next week, so maybe that'll fix that.

I hope I was clear and thank you for your help.

 

you check for any vaccume leaks

 

The 1st gen archives have a whole section on 13B idle.

 

The backfire (technically, afterburn) is probably caused by an exhaust leak.

Some details on the carb setup would be helpful for diagnosing the idle problems.

 

Thank you for the help.

I have checked for vacuum leaks but I'll spend the 10$ to replace the 10 inches of rubber to the brake booster.

I'll look in the archives. I have attached a few pictures on the setup. Maybe some smart people out there can help me identify what I have.

Please forgive my ignorance

 

Early 13B, vacuum advance Holley, may be a Racing Beat modified one due to the extended vent tubes. Could be a 465 cfm, but more likely a 600 cfm for the 13B. Also appears to have an electric choke. Best suggestion is to pick up a good Holley tuning book. You can pull the model # off of the choke horn and find out the specs for it. # is etched, but RB has a habit of removing model #s to protect their carb model choices and mods.