calculate afr edc16c9 astra 1.7

[bmw320cd]

hi to all
in my ongoing study I am having difficulty in calculating the afr
then I know that the afr is the ratio between the intake air / fuel injected
being that the edc16 work to "torque" I have come to understand that in order to find the afr at a given time proceeds so
- it is located on the torque limiter, the value that interests us, here, example at 4000 rpm 142nm
- you go in the map pair - diesel and I try to 142nm at 4000 rpm, and I find diesel required approximately 29,2 mg
- now I should find the map fuel - to-air ( which I can't find it,that ... is the lambda sensor, the upper and lower???) to find the related mg of air that goal that takes the car

and, finally, the relationship between mg air / mg of diesel fuel = ratio AFR

[switing63]

Unfortunately I can not download anything because I am a user still at the beginning, but if the MAF you have the values in Kg/h, according to me you can convert them to mg/cycle by doing a calculation like this.
Let's assume that you have a value of 12 Kg/h and the engine rpm to 850 rpm. If in a minute ago 850 rpm in a h will be 850*60 that is capable of 51,000 rpm, and at each round in a 4-stroke engine and 4 cylinders take place 2 aspirations, that is, 51.000*2=102.000 aspirations. 12 Kg are 12,000,000 mg and then dividing them into 102.000 aspirations of each cycle in the cylinder entering 12.000.000/102.000=117,647 mg