Magnetic Sensor is driving me insane topic

Hi all. I've got a nexus 7 (first one) and the magnetic sensor is driving me insane. I've got magnetic mounts on my car dash and have metal plates stuck to the back of my tablet so I can use it as sat nav, music, etc...... But if I don't position the tablet just right it turns the screen off. I really need to disable the magnetic sensor. It is rooted and running custom rom but I haven't a clue how to disable the magnetic sensor. Anyone know? I've looked around on here and Google but nothing. Thanks all.