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Old 11-04-2002, 05:14 PM   #8
Jon [in CT]
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Member#: 2992
Join Date: Nov 2000
Chapter/Region: NESIC
Location: Connecticut, USA
Vehicle:
02 WRX Sedan
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Quote:
Originally posted by AZScoobie
I check AF in the downpipe at the base of the lower bend. Day by day I realize that the stock Wideband is not the answer to tuning like we all once thought. My question is this... How do we know that the stock ECU is not adjusting for such backpressure? At least a known figure on a stock car....?
It is very likely that the stock front A/F sensor from Denso is also pressure-sensitive. Here's a quote from the 4th page of Denso's 1997 SAE paper about their sensor (see http://jon.in.ct.home.att.net/SAE970843.PDF):
Quote:
According to Kamo et.al. [4] diffusion at the diffusion layer can be obtained with the character of "Temperature Independence" or "Pressure Independence" based on the radius of the micro pore. For the automotive application, the "Temperature Independent" type diffusion layer is used.
I expect that Subaru has made measurements with the stock exhaust so that they can predict exhaust back pressure using, perhaps, MAF, MAP and RPM. Since Subaru knows exactly how EBP affects the Denso sensor, Subaru's ECU likely makes corrections to account for it.
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Last edited by Jon [in CT]; 11-04-2002 at 05:20 PM.
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