I recently just bought a Rx8 and put a used motor in it and so far everything runs great on it except the check engine light keeps flashing and when I read the codes it came up as a missfire in one of the cylinders. the engine doesnt seem to be missfiring though, it is running smoothly. I dont know if this is a common problem or what is wrong?

 

missfires are usually associated with weak ignition, how olw are the coils, plugs, and wires?
i hope you put new stuff in when you did the swap. if thats your problem you should search bhr. btw welcome, good luck, and search before starting a new thread, it will save you alot of flaming

 

+1 on the ignition system. You need to replace plugs and coils about every 30,000 miles. Unless you go with the BHR ignition mentioned above. That will pay for itself

 

thats the thing, the plugs, coils, and wires are all brand new. and usually when a car is misfiring you can tell just by the bucking of the engine as you drive but the engine is running great and even starting absolutely fine. I don't know what else you could fix to help solve a misfiring problem. I need to fix it before next month bc im due for inspection than. Im not familar with rotary engines so i thought misfires could be related to something else, thank you for your help

 

Which cylinder is misfiring?

 

thanks charles. i said usually because a lot of people not familiar with rotaries often overlook the inginition.

 

Thank you all, and cylinder two is misfiring

 

I've been having problems and they are just getting worse. When cold the engine misfires while (I think) it searches for the best alternate fual air map. Then after about 30-45 seconds of struggleing it smoothes aout and i can drive for hours with no problems. It does this each cold start, there is no remembering of teh best map. Now a more recent problem is more stumbling at start up and a not wanting to start when warm. It takes several cranks to get it started and seems to be worse when parked up hill. A complete stranger approached me at a gas station recently and suggested it was a worn out senser that fot worse when hot, maybe a cam position sensor. That kind of fits what Charles posted as causes. I have installed new plugs, wires and coils as well as cleaned out the intake (which cured teh stalling at idle problems). For complete disclose I believe I have a cracked block. I was giving off huge plumes of white smoke when cold and it would go away when warm (expansion would seal the crack). Putting radiotor stop leak fixed that problem. I cant afford much and would like suggestions on least expensive next diagnosis ideas. It sucks having a car I can't count on to start when warm even though so far it has always sooner or later started.

 

over 100k miles