Quote Originally Posted by 1project2many View Post
Please tell us (again if necessary) how you are determining this? There is a level of detail here that seems impossible. It's like reporting measurements to the hundredth of an inch using only a carpenter's measuring tape. The most likely way to determine this is to measure unfiltered O2 output with a scope concurrently with injector or ignition pulses for a cylinder based reference. If you are relying on individual cylinder injector trims to determine rich/lean operation you will be led astray.
I think they are doing the old fashioned "read the spark plugs" method. This is my guess. Whomsoever wields the answer, wields the power of one can of pop.