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Old 03-06-2013, 07:45 PM   #147
roger 04 rt OP
Beastly Adventurer
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Joined: Nov 2011
Location: Massachusetts
Oddometer: 2,371
Below is a plot of the O2 Circuit with Narrowband at the bottom of the chart, and an LC-1 at the top. The LC-1 is set to 13.8 (the red dotted line) but it would have the same look at any programmed AFR. The thing that jumps out is how solidly the Motronic locks the LC-1 onto the target AFR.

In the bottom chart the O2 Circuit & Narrowband was set to 13.8:1. The result was 14.0:1 at hot idle (the red line) and 13.6 (the blue line) at 80MPH cruise. Different loads resulted in different Closed Loop AFRs. Interestingly higher loads lead to richer mixtures which isn't terrible—some might even say it's a good feature. (Hotter exhaust makes the O2 sensor produce a given voltage at a richer mixture.)

This means the spread was ±0.2 AFR between idle and 80 mph and that was with the narrowband pulled a long way off its design point. There are some additional data sets below the charts. (Note that the first few minutes is very rich. That's the Open Loop Cold-Start Fueling.)

After two more test rides, I have a good data base at three settings. Setting 5, 7 and 8 are actual and setting 6 is estimated but I will ride it later. The data look pretty good. The curves for the various settings all look like the one above. Here are the different results:

S8: 13.8 ±0.2 AFR
S7: 14.1 ±0.2
S6: 14.3 ±0.15 (estimated)
S5: 14.45 ±0.125

It is my opinion that most bikes will run great at setting 6 or 7. An important point here is that when you richen closed loop AFR, the open loop fueling gets richer too, coming along for the ride through a process known as Adaptation.

As I said earlier, because of the heating, the mixtures get a little richer with higher loads. Looking at those numbers above, the lean end of the range occurs at idle and the rich end of the range happens at 80 mph.

There are still a few small adjustments to make to voltage levels and to the algorithm. Then a few pre-production units.

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