Different ignition angle across cylinders

Hi, I logged some data in 3rd gear WOT. The car in question is a Mini R53 JCW, running stock tune.

I am trying to understand what is happening with the ignition.

At 5036 rpm everything seems fine. Ignition across all 3 cylinders is the same.

Then at 5168rpm cylinder 2's ignition is a lot retarded compared to the others and to target/tune. What could be a reason why this is different?

Finally at 5682rpm knock is occuring, and the ECU retards ignition. I find it strange that this car is knocking on E5 petrol and with stock tune.

Spark plugs are changed recently, both with old and new the issues are occuring.

Coil pack and leads are less than 1 year old, from a reputable brand.

Could anyone share some thoughts about why both things could be happening?

About the only thing that comes to mind, at the moment, is that modern vehicles run very close to the fuel's limits for economy and efficiency and if the fuel isn't quite up to it - especially in the hot weather - it may be pulling it a little?

Do you have access to a better quality fuel you can use for a comparison?

It should not run lean, I've ran the same stock tune on another similar Mini, which does have an AFR gauge installed, and at that rpm it runs 0.72 Lambda, in my opinion much richer than necessary.

I am planning on measuring fuel pressure at the rail, and maybe swapping the AFR to the other car. Might also try different injectors?

We can try even better fuel, but it should not be the problem. E10 with 10% ethanol is most common here, and this car runs E5 RON98 fuel with 0% ethanol. The JCW certificate instructs to use a minimum of RON98, but we will give RON102 a go and see if it improves.

Running lean can increase the oxides of nitrogen, so stoich' is not uncommon. However that lambda is very rich, so may be worth investigating on that car!

Not sure what the supposed 0% ethanol in E5 fuel means as the E5 designates a nominal ethanol content of 5%?

Higher, unleaded, octane fuel should give some more data but I was thinking different fuel brands, preferably from a high volume retailer as the fuel should be 'fresh'.

This problem was solved by replacing the injectors.