Hi,

I'm learning how to tune for more then a year and now I'm facing strange behavior of my power delivery. Sometime it runs great but sometimes under WOT after 5,5k RPM it starts to knock on one cylinder (see knock voltage) and timing is pulled down. I'm attaching logs (from same day and hour) and below few points with my comments. The car is nearly stock TT BAM. There is 4 bar FPR (already tried to switch back to 3b FPR without difference) and stronger wastegate on the turbocharger.

- lambda control is decreasing fueling when my problem occure
- IDC is approx 10% less
- there is few missfires on other cylinders
- there is very big difference in knock voltage on cyl 3 when problem occure. Other cyl looks the same...
- when I look through spark plug hole the cyl no. 3 looks worse then other cyl
- compression is +-0,5b same on all cyl

Thanks everyone for attantion and help. Sorry for my english, I'm not native speaker.