Car is an '04 RX-8 with 54k miles on it. Current owner has owned it since 2008 and hasn't driven it in the winter. Current owner bought it with 46k miles on it.

Car hasn't been modded. Owner says that he gets a CEL "misfire" code (he didn't tell me the actual code) when the car is driven hard; i.e. to redline frequently.

Owner had Mazda replace coil, wires and plugs but problem - if it is a 'problem' - still occurs. Owner says CEL disappears if car "driven gently".

I will go look at it. Can anyone suggest what might be the issue, if any, with the car? Anything to look for when I look at it that might be specific to the Renesis engine, other than the usual used-car inspection things to look for? I will try to reproduce the problem and record the actual engine code.

I own two RX-7s, but never had an RX-8.

 

Misfires are usually caused by faulty ignition components--especially coils.

You should absolutely have any car you are considering compression tested before purchasing it.

These threads should be of great interest to you:

https://www.rx8club.com/new-member-f...t-here-202454/

https://www.rx8club.com/series-i-tec...t-here-222280/

 

Thanks Steve. Excellent thread on the misfire causes. Since the PO replaced the coil, a compression test seems to be in order.

 

Coils plugs and wires should all be replaced at the same time. The ignition systems don't just hold up on these cars. 20k miles is considered useful life of these components

 

The other thing to check is the catalytic converter. If it's partially clogged, it would give misfires at high rpm (as well as slowly kill the engine).

It would help enormously to know what the code actually is though!