I've been tuning my friend's turbo 4.8 2010 Silverado and I've come across something weird that I can't figure out. Sometimes while in PE the commanded AFR will go from the 11.29 that I'm commanding via the PE EQ table to a 12.24. It happens at frame 15,500 in the attached log. I'm thinking it must be time related because it only seems to do it on longer runs. Right now I have the AFR spark table set to start taking timing out a 11.7 so that when it goes lean it doesn't see knock but I want to correct this so I can up the timing again without having to worry about it.