I assume that it range checks with motor off, but does not range check with motor running.

make sure that the batteries for receiver and ignition are separated. Everything related to the ignition should be separated from everything related to the receiver by at least 12" or so.

try a new spark plug. Make sure it's in tight.

if you have a rubber boot over the plug, see if you can replace that with a bosch metal boot. This is what cured my interference problem.


peter