Problem has been going on for about a week now. Thought it was my wideband sensor going out but after actually feeling/smelling the issue happening i ran some logs on it.
Vehicle is an 06 silverado with the 4.8, has a spectre intake and speed engineering long tubes.
When driving it my wideband will suddenly go to a 16.0 reading and hold there, then it will swing to a 13.0 reading and stay. After a few minutes of this it will go back to acting normally. A few more miles and the process repeats. Giving more throttle when its lean or rich to get into what should be the PE area it will finally command for 12.5 af and WB shows it is getting there. Once throttle is reduced to normal cruise it will go back into being either super lean or rich. Truck has been driving fine without issue on this tune for months. Logs show that the 16.0 and 13.0 AFR is actually being commanded for some reason. This all came out of nowhere one morning when driving to work and as long as the AFR is right truck still runs perfect. Checked for basic mechanical issues and looked over all the plugs/wires for the O2 sensors and cant find anything obviously wrong.
Lean-rich-o2dropout12-16-18.hplLean-rich-o2run3--12-16-18.hpl CHA_1barmaf_v2.hpt
Here is the tune and 2 logs from today one cold start and one warm. Thanks for any help