I've read that the A/F at idle is supposed to be somewhere around 14.6/1 but nothing else and even that I am not sure is for the N12 engine.
Anybody have spec's for proper A/F at idle and under load for the N12?

 

Turns out you don't need Mini specific numbers for this one:

From Wiki: "Any mixture greater than 14.7:1 is considered a lean mixture; any less than 14.7:1 is a rich mixture – given perfect (ideal) "test" fuel (gasoline consisting of solely n-heptane and iso-octane). In reality, most fuels consist of a combination of heptane, octane, a handful of other alkanes, plus additives including detergents, and possibly oxygenators such as MTBE (methyl tert-butyl ether) or ethanol/methanol. These compounds all alter the stoichiometric ratio, with most of the additives pushing the ratio downward (oxygenators bring extra oxygen to the combustion event in liquid form that is released at time of combustions; for MTBE-laden fuel, a stoichiometric ratio can be as low as 14.1:1). Vehicles that use an oxygen sensor or other feedback loop to control fuel to air ratio (lambda control), compensate automatically for this change in the fuel's stoichiometric rate by measuring the exhaust gas composition and controlling fuel volume. "

So..... This raises another interesting question. I have a 2187 error (lean air fuel mixture bank 1 ) but when I dial in my Scan Gauge to measure Air/Fuel it get 14.6 at idle and warmed up low load? and when driving it drops down to 12.8 - 13 on acceleration. On deceleration it goes WAY up, but that makes sense when no fuel is being put into the system.