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Old 09-21-2005, 02:36 PM   #1
Scooby Newbie
Member#: 92865
Join Date: Aug 2005
Chapter/Region: TXIC
Location: North Dallas
2004 WRX Wagon Stg2

Default BOV Question

I know alot about cars and mechanics but not everything,especially turbos.Someone with more knowledge could confirm or shut down my theory.
I was just thinking about the 100% atmospheric bov and how the ecu is expecting air to recirculate back. Well wouldnt that only be if you shift with out releasing the gas pedal. I dont know how the turbo works but, like the throttle body, isnt it only open when you apply gas? So shouldnt you only run rich if you dont lift your foot when you shift.Doesnt help when ur racing but day to day.... just some hopeful thinking....heh anything not to drill a ****ing hole in my aftermarked p.o.s. Bov.
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Old 09-21-2005, 02:46 PM   #2
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Old 09-21-2005, 03:04 PM   #3
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Join Date: May 2005
Chapter/Region: NESIC
Location: New Fairfield, CT
'97 LegaSTi-2.5XTR
'96 BrightonCoupeWRX-SR30


that really doesnt make any sense...the ECU thinks it has air in the intake that it doesnt. The air went in through the MAF sensor and then it got jetted out into the air, instead of being used to supply the engine with the air that it needs bettween shifts. Therefore the engine is supplying the fuel but the air is not present. This occurs for a very short period of time with an atmospheric BOV but not at all in system with a recirculating BOV.

idk why you are thinking about drilling holes, that part really doesn't make any sense
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Old 09-21-2005, 08:42 PM   #4
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Chapter/Region: Tri-State
Location: Lovely Florida, NY
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1. Wrong forum.
2. Atmospheric venting is not bad for a MAP car or if the BOV is placed BEFORE the MAF. What is not good is (like on a stock wrx/sti/etc) the bov is after the MAF. What happens is the air is measured coming though the MAF and the ECU calculates how much fuel it has to add based on that and few other itmes. Now, with a atmospheric valve, when you get off the gas the BOV opens and releases the air which was already metered out of the system. Since the ECU still thinks it's there it's gonna dump the fuel it decided to add anyway. That give you a rich condition and a generally crappy running condition for a lil' bit. What the stocker does when ithe BOV or recirc valve opens is recirculate the measured air back into the intake track after the MAF. No rich condition because all of the measured air is still there.
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