Hello guys I have a nitro Kyosho drx rally car, anyway it works good I have tuned it quite a few times now but for some reason it makes a crackling popping sound when i have it sitting there idle and sounds like it will explode at any second but it goes really fast and doesn't use fuel too quick.
Anyway any ideas on how to fix this?

You might try asking this in the car section to get more knowledgeable people to answer. If it's like bacon frying, at least with airplanes that's a sign of detonation which is caused by a too lean needle valve setting.