I had interference on my JR9303 2.4 module system.  It was so bad that the plane rolled inverted on its own one day.  Move the batteries away from each other.  Put the ign. batt on the firewall and the rx batt. near the rx..  Get  as much separation(12in is recommended) as possible for all the components.  I also made an RF shield for the ignition module out of a tin can.  Now I don't have any interference.  My plane had one of those no-name, plastic box, chinese ignitions that are famous for the RF noise.