Is it possible? Coil issues

[mach9]

Do you think it's possible to have a coil going bad without getting code 33, 34, 35?

 

[yox185]

I don't think a weak spark would set off a code. Check them for arcing to the head.

 

[mach9]

Think I would be able to see evidence of arcing to the head? I'm only having intermittent or rough running under high load within midrange rpm. Doubt I can replicate how it runs when up on a stand.

 

[yox185]

Yes you can usually see black marks around the coils where the spark is jumping.