Lets Talk BOV:)

[sjbsuperman1425]

So i'm in the process of searching for a BOV. Since my budgets tight im probably going eBay knock-off Type-S or something of that sort (i know it has a weak diaphram and all that, i can fix it lol). But i've been reading about how people have problems with BOV's running rich/lean at idle and running rich between shifts, and blame the MAF. I see this as totally understandable, but as i thought about it, it seems to make sense and not make sense at the same time?

Say you are driving and your MAF is measuring, and turbo is building boost, blah, blah, and all the A/F jazz, then you shift..PSSSSSSH! but you dont get back on the throttle? why would it STILL run rich? all that air is not going into the engine anymore, and even without a BOV or Recirculation (i have CA18DET no recirc), all that air would be going to the turbo, and exiting out the exhaust, correct?

now when you are REALLY on the throttle, and just shifting those gears nice and fast, i might see a problem, because some of the measured air would still be in the pipes if no BOV or recirc was present. But even with a BOV, air is always coming in and the turbo is still spinning, probably not enough to make the needed amount of boost to compensate for the fuel being put it, but i'd think that the ECU knows when the throttle is closed and should lean it out a bit and it shouldn't run lean.

I would like to hear other peoples experience and opinions.

[480sx]

When you have a vented bov and a MAF the following happens. Your MAF measures an amount of air. That amount of air is called metered air. When you shift in boost and your BOV opens, it released that metered air. This causes your ECU to think that there is more air than there really is in the system, and adds the extra fuel to compensate.

[sjbsuperman1425]

i understand that. My arguement, which could be wrong lol, is that when driving under boost and you shift from 2nd, then just go to neutral, or are parked and rev the engine and what not, why would it still run rich? all that air is not going into the engine since it was blocked by the Throttle plate right? Does it only happen when constant driving?