Hi Mike, forgive me for not explaining the chart in the first post, I was trying to draw a comparison between Co, lambda and air fuel ratio, let me explain, what ever value have you run across or up to the green line and read off the corresponding value, for example- if you have a Co of 3%, lambda will be around 0.92 with an air fuel ratio of about 13.5 to 1.
In the Chart below I have added a pink band for wide open throttle (WOT), yellow for idle and the thin blue line at the bottom is for cruise, the advised idle Co for my car is 1%+/- 0.2 and over the past few years at MOT time it has never been below 3% Co with HC of 160 ish this is a pass due to the limits being 4.5% Co and 1200 HC, the car never idled or ran well with the Co lower than 3%, now after finding out that the WUR is the root of my running problems I have a idle Co of around 1.5%.
I too have seen that lambda is to be ignored at WOT and in the past I would have agreed with that statement but if your full throttle enrichment system is not working correctly and enrichment dose not happen damage to the engine will happen.
From my observations on using an air fuel ratio gauge for the first time as you open the throttle their is a clear step at around 0.89 lambda on acceleration as the throttle opens past 55 degrees and the enrichment device is triggered lambda drops to 0.82.
