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Location:
melbourne
Registered:
November 2003
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Location:
Brisbane
Registered:
May 2002
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Re: turbo's ( AFM with bov?)
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Sun, 15 May 2005 08:03
 
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WHen you take your foot off the accelerator, the air going through the throttle nearly comes to a standstill... and the air going through the AFM should nearly come to a standstill also. The presence of an atmo-venting BOV allows a differential to exist, and that's where the fuel mixtures get screwed up.
There's no reason to have an atmo-venting BOV on an engine anyway, whether AFM or not. They're also illegal. Plumb-back works just as good without any of the problems above, but of course they don't sound as hektik. 
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Location:
melbourne
Registered:
November 2003
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Re: turbo's ( AFM with bov?)
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Sun, 15 May 2005 10:23
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well the whole point of the BOV of any kind is to reduce the back pressure on the forward spinning motion of the turbo, which i rekon sounds pretty beneficial, especially when driving hard.
so u dont think an atmospheric BOV will be beneficial at all?
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Location:
Brisbane
Registered:
May 2002
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Re: turbo's ( AFM with bov?)
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Sun, 15 May 2005 11:38
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There is no benefit over a plumb-back BOV. They both acheive the same thing, but the plumb-back doesn't have the nasty side-effects.
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Location:
Bundaberg, Qld.
Registered:
May 2002
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Re: turbo's ( AFM with bov?)
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Sun, 15 May 2005 11:42
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a atmo bov on a AFM will normaly cause you to run rich on gear shift. sometimes people may see a puff of black smoke after gear change on a atmo afm turbo engine. excessive richness can wash the bores which in turn can wear the rings down faster.
i run a atmo bov on my AFM 4agte, the engine still runs fine so it doesnt bother me. though the noise starts to get annoying after a while.
will be converting mine to a plumb back once i make the adaptor.
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Location:
Carlingford, Sydney
Registered:
May 2002
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Re: turbo's ( AFM with bov?)
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Sun, 15 May 2005 12:37
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haha same with mine, i got over the noise in about 20min 
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Location:
Sydney
Registered:
September 2004
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Re: turbo's ( AFM with bov?)
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Mon, 16 May 2005 08:54
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| feral4mr2 wrote on Sun, 15 May 2005 21:42 |
a atmo bov on a AFM will normaly cause you to run rich on gear shift. sometimes people may see a puff of black smoke after gear change on a atmo afm turbo engine. excessive richness can wash the bores which in turn can wear the rings down faster.
i run a atmo bov on my AFM 4agte, the engine still runs fine so it doesnt bother me. though the noise starts to get annoying after a while.
will be converting mine to a plumb back once i make the adaptor.
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I have an Atmo BOV on my 3SGTE equipped with AFM (came with the car, when i can afford it im going plumb back too) and most of the time it behaves normally, but occasionally the richness can cause a small backfire after changing gears if the cat/exhaust is hot enough.
To answer your question about how the AFM behaves. My S-AFC shows my AFM opening as a precentage. I have watched this when I change gears under boost, and when the throttle closes and the BOV operates the AFM spikes along with the psssht (sorry, didnt mean to go all technical there  ) Because air is now allowed to flow thru the BOV, not the throttle this adds to the richness, and out of whack A/F ratios.
However once the BOV closes and your driving away there doesnt seem to be any after effects to this A/F ratio change. Although some people have posted that their engine runs rough for a period after the BOV operates.
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