Hello and thank you for looking at my thread.
I have been doing TONS of reading and experimenting with tuning on my recently acquired 2009 Cobalt SS.
I basically followed Backyardturbo_FTW and cobaltssoverbooster guides on how to dial in the MAF. ***THANK YOU TWO for all the great guides!***
My thought was to make my main focus getting my trims dialed in.
I thought I had it pretty good. 3 days of logging and I had things nailed down to ~-3 STFT so I thought.
Today I fire up my car and boom suddenly it's more around -18. I made ZERO changes to the tune. In fact I haven't flashed anything to my car since I was averaging around -3.
This has happened to me before with this car when trying to get things dialed in trim wise.
I have removed and inspected every element of my intake piping and did a check for vacuum / boost leaks.
I had a brand new MAF sitting here handy incase this happened again. I threw the new OEM one in and it made zero change.
Does anyone have any suggestions as to things I might check? My logic says if I had a post maf leak wouldn't I see positive trims since unmetered air was getting in?
I am wondering if my primary o2 sensor is failing?
If you guys have any input I would greatly appreciate it.
See the two logs + my current tune.
Thanks!