Went lean...

Bewy said

7miles,
Responding to the problem of secs too rich. Have you checked that you are getting WOT with your foot on the acc pedal? You would be surprised how many people never check this....& do not get the expected WOT performance.
In your messing around could you have disturbed the throttle linkage?
Secs not fully open can change distribution & give odd O2 readings.

Click to expand...

I think "secs" must be an auto spell correct issue. If not, I'm not following it. That is a good question. I did check it, when I first saw it was overly rich at WOT. Thinking if the throttles opened all the way it would get more air. I found that the throttles WERE NOT opening all the way. So I changed where the pedal connected to the linkage and the result was a) it opens the throttle all the way, b) the pedal resistance slightly increased ... which is actually pretty decent, no better no worse. The AFR result was very little changed. It was still at that time, too rich.

I tend to think it wasn't due to throttle linkage because if it weren't opening enough, the AFR would still respond mostly linearly to wherever the throttle did open up. It's got to have been the choke partially closed. Best I can guesstimate.