This #4 ignition module sounds like what I'm experiencing. The plane is in my storage unit at this time. This weekend I'll check. If the weather cooperates I'll get some RPM readings. Where do I look for the #4 mark? Where would I find the 8.4v mark. I'm almost sure I can't run higher than 4.8v with this module because I recall I couldn't run a 6v pack to power it. If I do decide to change it, do you guys have any recommendations as far as brands go? Thanks again for your help.