Well, looking at the logs clearly this low res voltage is not equal to retard, in fact, there are I think voltage spikes where no retard is added but reduced. Nevertheless, I was just curious how it looks. The only thing I wanted to know if that, as it is presented, looks normal to you.

Nope, that's not it either.

You have some knock ears or similar whether mechanical or electronic, home made or bought that you can hear clearly what is going on?

I found a top accessible spot to bolt this on to the head, not ideal position but working. (Also turned out the line is too short - I made it for a smaller car and me sitting in the passenger seat :/, but never mind).

The log from the drive attached. I do not have knock trained ears, but I do remember the knock sounds from the previous project on an engine from the same family. I now defo heard this characteristic faint "metallic" tweeting / chirping sound on these two accelerations that have the retards showing in the log. I really wanted to record this, but I do the drives alone and it was just impossible. It does not sound like anything resonating or rattling against the engine.

So now, why do (I think) I have this knock? As said previously I played with the ignition, both ways actually, added up to 4 degrees, but also subtracted 1.5. And with the fuel. Now in the attached log it was all stock calibration for regular fuel (95 prescribed I think) running on E75. Earlier today I also logged a long drive when I was happily accelerating at different RPMs, but not doing many pulls from lower ranges. Much less retards there, but still existing. Could this have anything possibly to do with ignition tip in? I am inclined to do one more fill up with E85 to get higher ethanol content still, but at this point it should not matter, right?

Many thanks for looking carefully at my log Myself I have been thinking a lot, read and watched a couple of useful things. My last evening conclusion was that I should try to see what happens when I bring the ignition much closer to ZWOP (but with still some reasonable distance). This ended up in considerable ignition increase, in the low rpm / high boost area up to 14 degrees plus and down to +5 towards lower boost and higher RPMs. In any case, much more brave than before (I also felt that the stock ignition is very low).

And guess what - this did not make things worse, if anything it made things better. Still single retards of up to 3 degrees, engine feels much better, and for the very first time in a long while I could hear the turbo spool up like in my previous car. The pattern of retards also changed. And I managed at least twice to have my classic pull 1500-4000 rpm in 3rd with no retards. And the engine is still alive.

So, taking into consideration what you said, and adding the fact that I also effectively lowered EGTs with this I am now thinking oil / pre-ignition. The retards coincide with high modelled EGTs (I know this is not a measure, but no EGT probe yet). More so, now that you reminded me of that, I promised myself long time ago that I should clean and declog the oil separator. (Otherwise, I am not sure what the overall condition of my engine is, never took it apart, but I do take care of it in terms of basic service, and spark plugs are new BTW).

And yes, I know I try to do too many things at the same time (never said that, but in parallel I was experimenting with cranking fuel, finally got that right too I think), but I do not have another possibility.

In any case, experiments with E85 suspended, due to logistics I had to fuel up with Ron98 and will be flushing E85 out now and removing the sensor. Will come back to testing after summer. In the meantime, I will reanalyse my code for improvements and perhaps give the engine one more careful look over and do something about the oil separator.

pre-ignition is inaudible, no knock sensor can or will ever pick it up, but you'll know it happened when you have a hole in the piston.

Sounds like there is no knock and something is banging against the block to me.

Mostly to keep this thread alive As said earlier, due to logistics my E85 tests are suspended for the summer, but I was reviewing what I did and thinking a bit what I missed (having a full dash support for E-content display and correct low-fuel warning would be nice, but that's a different story).

The question - is it worth at all in your opinion to also mod the PCV duty cycle according to ethanol content to get a even more on-spot AFRs before STFT? I was getting the impression that on steady-state driving the STFT drifts slightly upwards to keep 14.7 and was thinking that that could be it, but not really sure. Modding TATEMSN is not a big problem (mod its linear I believe input vs. E-content), but not sure if it would be a waste of time or not.