Unfortunately I'm no tuner myself so I probably couldn't give you the finer details.. but didn't I just explain the basics above?! A lot of the further problems you have payed mention to are associated with the heavy fueling of standard ECUs.. and of course, running an AFM. It aint the BOV's fault!!

For reference, an AFM and MAF sensors are one and the same! (MAF- meaning 'Mass Air flow'... As opposed to MAP sensor- meaning 'Manifold Absolute pressure'.

A MAF reads the air stream running through the device, usually by hot wire resistance etc. As explained PREVIOUSLY above, when the throttle shuts and activates the atmospheric BOV, a pressure drop is experienced between the turbo compressor and the throttle body. Due to this drop in pressure, MORE air will be drawn from the turbine.. resulting in an increased volume of air being measured through the MAF sensor. This increase is perceived as 'load' by the ECU, and so more fuel is added to the equation- this is where your backfires etc come from!
By running a plumb-back BOV, this pressure drop is balanced out due to the air being recirculated and placed just after the MAF... therefore filling the 'extra volume' of air that is being drawn into the turbine due to the pressure drop INSTEAD of the system needing to 'suck' more air through the MAF to complete this balance.

In contrast, a MAP works off positive/ negative vacuum and is generally taken from a vacuum line which sits on the manifold... and here's the important bit, PAST the throttle body! This means that when the throttle is wide open the MAP sensor sends info that the ECU detects as 'load' and extra fuel is added according to these readings. Because a MAP sensor is based on vacuum and NOT air running past a hot wire resistor... an atmo BOV does not interfere with the readings because when the throttle is shut, the MAP is reading NO load point on the engine!! NO LOAD POINT= NO EXTRA FUEL!!!

This is why I say running an aftermarket ECU can 'tune out' these bugs... and, that atmo BOV's have nothing to do with the root of the problem.
SO STOP BLAMING THEM OK!!!

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"...even my Grandma can drive fast in a straight line"