[Diy_efi] WBO2 and AFR

gary gas-
Thu Jul 7 19:45:26 UTC 2005


> > Does the turbo muck up the partial pressures at all, or are they 
> > pretty constant pre- and post-turbo?

WBs are pressure sensitive.  EXPECT, it to read richer than 
actual, when the AFR used, is richer than stoich (14.7), and 
leaner than actual, when the AFR used, is leaner than stoich 
(14.7).  The further from stoich, the greater the error.  An 
exact amount of the error?  :shrug:  The preferred/ideal 'fix' 
for this dilemma, is to use individual sensors to monitor each 
cylinder for comparative analysis, with intent to tune all 
cylinders even, then recheck the true POST turbo AFR.

GAS

----- Original Message ----- 
From: "Jay Wallace" <wallkatt at netzero.com>
To: <diy_efi at diy-efi.org>
Sent: Thursday, July 07, 2005 9:57 AM
Subject: RE: [Diy_efi] WBO2 and AFR


> At 04:54 PM 06-07-05, you wrote:
> > What happens in this scenario when you add a turbo upstream 
> > of the WB02 sensor?  Does the turbo muck up the partial pressures 
> > at all, or are they pretty constant pre- and post-turbo?
> 
> This seems to be very interesting and important question - if the 
> exhaust backpressure at the sensor goes up by, say, a factor of 2 
> then the oxygen partial pressure would also increase by a factor 
> of 2 without ANY other combustion changes occurring. The obvious
> way to correct for this is to simultaneously measure the exhaust 
> pressure at the WBO2 sensor and divide the oxygen partial pressure 
> by the total pressure, giving you the fraction of oxygen (pressure 
> basis) in the exhaust stream. Or am I missing something obvious here?
 




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