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Old 11-18-2012, 07:18 AM   #3164
roger 04 rt
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Joined: Nov 2011
Location: Massachusetts
Oddometer: 2,272
Originally Posted by The Evil Twin View Post
Just had the GS up on the dyno yesterday. Interestingly the AFR was consistently between 13.5- 14:1 at cruising speeds (40-80 mph). As a matter of fact, mostly between 13.5- 13.7. Only down low in the RPM (>3000) range did it exceed 14.5:1 . The peak probably being when the throttle opened abruptly.
I have a full system waiting to go on and will be returning to retest. According to BMW, the EFI will not take any time to adjust, but I will ride through at least one tank first.
Most dyno runs are made at WOT so I guess your's were. Torque and Horsepower are then derived from the rate of acceleration. So you probably know, but I'll mention, that those AFRs are not what you would measure cruising at those speeds. For WOT acceleration, those AFRs are relatively lean.

If your we're on a different type of dyno you could measure AFR under load at steady speeds. Even up to 100 mph my 1150 has gone into Closed Loop which means the AFR will be set by the transition point of your O2 sensor which is 14.7:1 in your case.
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