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Old 10-01-2002, 10:05 PM   #15
thejean
Scooby Specialist
 
Member#: 17763
Join Date: Apr 2002
Chapter/Region: W. Canada
Location: Calgary, AB
Default Re: Re: Re: Not to butt in or anything, butt..

Quote:
Originally posted by n2xlr8n

Exactly how rich I am is what I'm trying to get from Jon or Jorge (by interpolating the mv value of the WBO2 as seen by the UTEC)....I don't think I'm anywhere near the "unburnt fuel in the exhaust" stage or "high EGTs", simply because my EGTs are still around 1400F at max boost, and there is no evidence of detonation (which can also occur when too rich). Your concerned is well aimed, though...... Keep up the dialogue, JC, you are one of the most diligent hungry-for-facts person on this forum.
thanks, its nice to be appreciated! anyway, based on Jon's graph, it appears that the breakpoint in the curve is about 12:1 and you would go very rich, very quick beyond -13mA. direct interpolation will not work. extrapolation will however. but, basically, if you keep the amperage greater than -15mA, you'll be above 10:1 which is fine. so, tune for "rich" with a front 02 sensor amperage greater than -15mA? Is this what I'm reading out of all this?

the chart quickly shows why the stock lamda value goes srewy at A/F's less than 11.2:1. the stock ecu algorithm likley has an equation to describe the relationship Jon showed at more than 12:1. now, if you extrapolate that curve to left according to the same trend that is exhibited above 12:1, you can see how the equation would not report accurate A/F's.

TXS, i hope your listening to this next statement... I believe that you don't need an upgrade for the UTEC. Mathematically, we could estimate the curve that the stock ECU would follow and looking at the actual curve that Jon posted we could figure out an equation to describe the correction factor when A/F's are less than 11.2:1. Then, just program this into the UTEC and there you go, you can now measure A/F's down to at least 10:1 and maybe even lower. Yuo could even go lower than that but granted, it would be a little more "blind" as we don't have a curve for that area. plus, the current would become close to the -15mA limit. Can anyone comment if this truly is a limit or just a function of the presentation of the graph? Jon?

jc
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