Was driving on the freeway the other day and suddenly my RX-8 started running very rough with a noticeable loss of horsepower. Soon after the engine light came on. Minutes later it started running normally but would eventually go rough again. I had AutoZone run a diag on the engine light and it showed misfiring. So I bought new spark plugs and had a repair shop install them. The engine still ran rough. They blamed the new spark plugs and put the old ones back in but it ran rougher than before. They eventually blamed it on an ignition coil. I drove it home and it ran horribly, but then suddenly started running normal again for a couple minutes just like before.

Does anyone have any ideas on what might cause this? I don't want to go buy new coils if that's not the problem. Is there an easy way to check?

Thanks.

 

Its probably coils/plug wires.

If you want to test them before purchasing there is a TSB that details it.

Stock coils stink. Mine only lasted 45K. Some guys change them yearly as routine maintenance.

 

coils