RC Only Works When Engine Not Running?

It may seem crazy, I've Googled it and can't find any information. A few weeks ago I changed my car system and turned it into LPG, I am not certain whether this matters or not because my RC had failed some before I changed the gas system. Still, I changed batteries and tried different positions and just realised that my RC would not work as long as the motor is running. Every time I need to either open or close the door I have to stop the engine and then it will work. Has anybody had the same experience? It would be nice to know I am not the only one. Thanks. I am writing from Lima-Peru.