Solved

[Nick's e30]

Does the small black box on top of the stock airbox have any sway in air control? I just realized mine was missing and I have a misfire that has started. Wondering if that could be related before I tear through the spark plug-wire-rotor cap side of things.
Thanks all!
Nick

[Quinthirty]

Does the small black box on top of the stock airbox have any sway in air control? I just realized mine was missing and I have a misfire that has started. Wondering if that could be related before I tear through the spark plug-wire-rotor cap side of things.
Thanks all!
Nick

The black rectangular plastic cover (w/ BMW logo) houses the air filter has no sensors in them. Its the silver device after the airbox that has a black square plastic cover that is the potentiometer / sensor, but I don't think the AFM would be a concern just yet as the backfiring sounds more like a spark-related issue as you've mentioned. Just include the ignition coil in the list...