08 Outlander subwoofer upgrade
 

So when I bought my outie it had one of these Chinese double din units in. I bought a OEM RF sub enclosure and wired that to my pioneer mono amp. It had a lot of interference when the engine was running. Thought it might have been because I used 1.5 mm Square cable. Upgraded to 4mm square but still had interference. My amp switch wire comes from Acc power. I thought it was that and switched it direct from battery but still interference. Please help. TIA!!