P0171 (lean), possible false reading

[MurderousPandas]

Update for all:

New MAF and upstream O2 / wideband knocked down fuel trims by about 5. Not the issue, but noice. Good to know new sensors are in there too.

New headers because why not try, only $500. Knocked down the fuel trims by about 25. Probably the issue. No signs of cracks or leakage on the old, but i did notice the flex pipe parts were looking a wee bit worn. They were those open mesh style flex pipes that naturally leak a little i'm sure, but i'm guessing that was the cause. Don't know why it took about 7 or 8 years to become an issue, but anyway...

Negatives: both middle header nuts kinda took a shit on me. The passenger side nut rusted to the stud, so it is now a bolt, still works, but shit. Driver side is stuck halfway up the stud, so it's not holding the header down. Hoping the two other nuts secure the header/gasket down enough and copper gasket stuff helps seal whatever little bit is needed.

Tips: header gaskets are a bitch, used some exhaust copper gasket stuff to help seal a tiny bit more and act as glue, put the gaskets on the block and they stuck pretty well, making the headers slightly easier as you don't have to line up the headers, gaskets, and studs all at once. Also, use a copper grease on threads of O2's, mine came off fairly easy and clean from the old headers because so.

Lessons: fuck mesh style flex pipes. Also, 7/11 gas isn't as nice as Shell. Also also, clean threads to header studs, they're probably a tad rusty and might be a problem when reinstalling.

End result: LTFT is reading near 10, so much better. Have yet to do any driving but around the block and it was still dropping very slightly, so hopefully we can get that closer to 5. Situation resolved. Will likely get header studs fixed the next time my TOB needs replacing.

[Sam86]

Have you checked the PCV piping, I had this code and all issues you described, the issue turned out to be the PCV pipe wasn’t on properly after catch can install