Hello Kim and to all, thank you for this continued feedback and all the posts.
These make for thought provoking discussions and challenging scope techniques for sure.
I hope the information posted here promotes the use of the scope when looking at broadband sensors as we can now see true response time and fuelling activity.(Not so when using a scan tool)
Not sure I have an explanation for the periods of inactivity of our broadband sensor when installed to these diesel engine vehicles but this is not uncommon.
I too was amazed when monitoring activity across a BMW 318d broadband sensor during climbing and deceleration, at how little response there was from the broadband sensor, so doubting the whole technique!
My thoughts surrounding the clear activity during gear changes would be as expected and indicated in your image above, where we have a sudden change in fuelling during momentary deceleration, (Lean) followed immediately by a gear change and then acceleration accompanied with the applied load (momentarily rich). Similar to how we shake a response out of a broadband sensor using repeated WOT techniques.
From my experience it seems easier to see the system lean thanks to over-run fuel cut, but difficult to send the signal rich.
Could this be testament to modern engine managements systems and the finite control of fuelling under load conditions (Diesel)? Zero mA output during period of acceleration between your gear changes
When we look at fuel consumption for diesel engines in comparisons to petrol, diesels tend to produce similar fuel consumption figures whether you “drove it like you stole it” or potter from A to B, however, the same cannot be said for petrol and reading a long note on Wikipedia :
“For any given partial load the fuel efficiency (mass burned per energy produced) of a diesel engine remains nearly constant, as opposed to petrol and turbine engines which use proportionally more fuel with partial power outputs” http://en.wikipedia.org/wiki/Diesel_engine
Another theory regarding 0 mA output during buffers 5 and 6 could be characteristic operation of broadband sensor control (PCM) during “foot off gas” over-run fuel cut conditions
Would there be any value in pumping oxygen out of the broadband sensor measurement cell under these conditions when no fuel will ever be applied under these driving conditions?
Massive food for thought all round
Looking at buffer 6 there would appear to be activity form the broadband sensor, possibly due to “foot back on gas” or fuel re-established after the fuel cut, deceleration period?
Thanks again take care…….Steve