I made a post here a few days ago after purchasing a ‘Chinese’ adaptor from Amazon and having this problem:

With the engine on Torque makes the BT connection OK, however

b) Torque only displays data from the PDA’s internal sensors, doesn’t display any OBD data, not even RPM.

Eventually I sent the Amazon adaptor back and purchased another one, very similar, from here: http://tinyurl.com/l627oz6

On this vendor’s web page is this statement:
PLEASE NOTE ANY OTHER DEVICES PARED TO YOUR PHONE WILL NEED TO BE DELETED BEFORE ADDING THIS DEVICE. YOU CAN ADD THEM BACK ON AGAIN IMMEDIATELY AFTERWARDS.

Initially, with the new adaptor, I got exactly the sames symptoms as with the previous one. However, having read the above advice I followed it and – magically – everything worked!

It looks to me as if (on my device, using Android 4.3, at least) Torque always connects to the first BT device connected to the Android phone, regardless of the setting in Bluetooth Preferences | Device.