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Old 06-09-2003, 04:37 AM   #1
Unsung Boxer
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Join Date: May 2003
Location: WA state
Default BOV to Atmosphere

Gonna Boost my 1998 EJ22 here soon, To avoid porting the BOV back into the Intake, can't I use the SAFC to keep it from spazzing out? I would rather go to atm instead of back into the intake if possible.

I heard you can only do this if u have MAF equipped vehicle... somoene explain this too me please.
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Old 06-09-2003, 09:25 AM   #2
Mancini
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If your car is running a MAP sensor (measures manifold pressure) then you can vent to atmosphere without correction because the air is measured after the BOV would have opened to atmo. The air is metered inside the manifold. But you're running a MAF which means the air is already metered before the BOV, so the BOV would be releasing air that has already been accounted for. This will mean make more fuel available than there is air, richening the A/F ratio and causing problems. To avoid this you would need to return to the intake after the MAF sensor but before the turbo compressor inlet.


With a MAF you can vent to atmosphere without correction but you'll have serious drivability issues, stalling on decel or idle so I wouldn't recommend it. The MAP would require no correction. Now as for tuning out the the drivability issues, I believe the SAFC can do it using the decel function. But, I haven't really tried it yet cause I've had no issues at all when retuning to the intake and I like the smooth drivin! Haha...

Sorry I couldn't give more detail on how to tune around it, but hopefully that helped explain a little why us MAF guys return and some others don't.


Brian

PS. The big thing with DSM guys these days is replacing hte Karman sensor with a GM MAF and it running blow through (after the turbo, right before the intake)....interesting idea huh?
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Old 06-09-2003, 11:36 PM   #3
Unsung Boxer
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The reason I ask this is really silly. I have the stock WRX bov, but it is missing the part that bolts to it so you can connect it to a hose. In addition, I need to build my own intake piping, and It would be way easier to not even have to port the BOV back into the intake (and of course the side effect of louder BOV)...

If you get a chance, mess w/ the SAFC decel function, and let me know if u can get it to run correctly. The reason I asked this question was to figure out how to use that function to correct it.

I am worried that I wont be able to get it tuned enough to run the first time i boost it. we'll see.
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Old 06-09-2003, 11:52 PM   #4
Darshu
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98RS w/ EJ207
2010 Mazdaspeed3

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To add my recent experience, I tried and failed to make the car acceptably driveable venting to atmo with my MY98 RS. It was great on the highway and idled just fine, but I had to clamp MAF voltage to ~2.2% at NE1 and 2.3% at NE2 to keep the car from stalling outright when I clutched in. At clamp values that low, you'll end up with a car that likes to lurch alot in traffic. I'd recommend finding a way to re-route to the intake.

Also, the BOV I was using above was a TXS Type-H that is actually designed to vent to atmo and will close all the way at idle. If you're using a stock WRX BOV, your car may not idle reliably at all -- effectively you'll have a big vacuum leak.
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Old 06-10-2003, 03:37 AM   #5
Turbo GC4
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