vwlover77 wrote: ↑Mon Apr 22, 2019 12:03 pm
This is from a forum for BMW motorcycles that use Bosch fuel injection. Seems like the AFM is nearly identical to one for a Bus, and I found the calibration procedure very interesting.
Somebody with a stock, untouched, late bay AFM needs to map theirs and publish it here as a baseline for us to work with!
http://www.k100-forum.com/t11055-bosch- ... on-summary
I found it utterly unworkable, because it is firmly mired in numbers, and has essential errors right off the bat, namely, that it is an "air mass" measurement device. No, it is not. It is an air volume measurement device and the shape of the duct is what gives us the variable air flow/voltage reading graph. At maximum torque, the engineers know that the engine is at maximum fuel requirement. As the rpms increase from there, the volumetric efficiency drops and the fuel mixture actually has to drop off. By expanding the duct and watching the vane become less and less involved with the air stream as it moves out of the way, we get our desired result. Now I have sussed out a power circuit, that I have occasionally experienced as full throttle enrichment, and I was hoping that I would discover the last resistor gave a bigger drop in resistance, but I could not glean that from the article.
I am glad that we here get to adjust our air flow meters with an awake patient telling us exactly how it feels, namely, a running engine giving us real-time feedback.
I hungrily attacked that article looking for some answers to my own nagging conceptual questions, like is there a full throttle enrichment, is there a fuel shut-off based on off-throttle resistance readings, but it is more of a resistor board plot test. Interesting yes, and thank-you for posting it.
Colin