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Old 07-24-2003, 05:54 PM   #37
Jon [in CT]
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Member#: 2992
Join Date: Nov 2000
Chapter/Region: NESIC
Location: Connecticut, USA
02 WRX Sedan


Originally posted by Klaus
The properties that change with gas pressure are sensor current (raw lambda) and sensor response time. They do not change proportionally. So from the difference pressure compensation data can be derived when comparing both to the free-air current and response time (free air assumed at normalized sea-level pressure).
Thanks for the quick response, Klaus. I think I understand how your pressure compensation works. I think it depends, for one thing, on the assumption that when the throttle suddently closes (like during a gear upshift) then the A/F ratio and pressure of the exhaust gas will abrubtly change to that of "free air assumed at normalized sea-level pressure."

So, if the LM-1 assumes this is happening and expects that the sensor's pump current should take x milliseconds to rise to that of free air after an abrupt shift in lambda of, say, from .7 to free-air, but instead the LM-1 observes that the actual sensor response time was only x-y milliseconds, then the LM-1 knows that it was underestimating the exhaust gas pressure (and over estimating lambda) at .7 lambda and it adjusts its estimation of exhaust pressure and its related lambda correction factor.

I was surprised to find that the Bosch sensor reads deeper into the rich zone than does the NTK. Anyone want to buy a new, in-the-box NTK L1H1 sensor?
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Last edited by Jon [in CT]; 07-24-2003 at 06:07 PM.
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