I’m not trying to tell you what you should and shouldn’t do. I am just speaking from others (and my own) experiences. Your car, do what you want to with it. With that being said……
The MAF is used to determine how much Air is in the system from the time the air passes through the MAF, to the time it gets mixed with fuel. The MAF sends a voltage to the ECU, which adjusts the amount of Air to Fuel on a consistent basis. It even keeps track of this number between shifts. If the air is not recirculated, then the car will run rich. On cars with MAFs and BOVs, The MAF is usually repositioned somewhere after the BOV, not before.
Injected fuel can be determined by measuring the air-mass flow into the engine and divide it by the air/fuel stoichiometric ratio. The air-mass flow sensor may typically be located far from the cylinders, close to the air filter. Consequently there is a large volume consisting of hoses, intercooler, and intake manifold separating the air-mass flow sensor from the cylinders. Volumes introduce filling and emptying dynamics and a transient in the air- mass flow to the cylinders will therefore deviate from the measured air-mass.
Air flow to cylinders based on the Speed-density principle. The speed-density methods uses volumetric efficiency, engine speed, and intake manifold pressure and temperature to determine the air-mass flow to cylinder. A drawback of the speed-density methods is that the intake manifold pressure is subjected to noise. To reduce the intake manifold pressure noise, caused by engine pumping and standing waves, observed for mean intake manifold pressure have been proposed.
If we look at the motor more closely we will see that there are also a MAP and intake manifold temperature sensor present. The Mazda does not use the MAP to determine pressure, it is there just to "watch" that the highest pressure is not exceeded.
I believe Mazda also monitors the throttle plate angle (Still learning as much as possible on this) and of course the engine speed. It uses its air mass controller to boost to target air flow. For an example when the waste gate is opened the air mass flow decreases momentarily until the air-mass controller has opened the throttle more. This is done because the throttle controller tries to maintain a constant air mass flow.
Sooooo if we go and replace the BPV with a BOV the following will happen when gear is changed during WOT acceleration. When the throttle plate closes both a BPV and BOV will open. BOV tosses the air out and when the valve closes there will be an increased air flow through the MAF. I see that the error of measurement and mixture is caused by this rather than the all ready measured air being lost.
So not only will a surge hurt the snail overtime, the car will be running rich at certain moments. Rich is always better than lean, but neither will give optimal performance.
Again your ride, whatever makes you happy is also important ;-) Seeing yours also recic' air you should be good to go.
B-[/b]
Since you seem to have the answers, I have a question for you. Is it possible to recirculate too much? With mods. like downpipe, upgraded intercooler, etc., we are moving more air through the system than the car was originally designed for. I'm not sure why but the MS6 seems to accelerate more smoothly with the Dual Port BOV by just venting a little bit but still mostly recirculating. I've tried the TurboXS BPV, Forge BPV and the Dual Port and I'd say that the car runs the smoothest with the Dual Port. I always felt the acceleration was not as smooth with 100% recirculation. Maybe it's just my specific mods. that cause this to happen.
