So apparently I'm still fighting this code. When I changed out the purge valve, I disconnected the battery for a while and the ltft were reset to zero. Over time, they've gradually shifted back to negative values. The truck is constantly trying to pull fuel. At idle, in park or neutral, the LTFT shifts to about -10 on both banks. In gear, about half that. I don't understand why the massive difference other than the difference in load on the engine. While driving, they are still negative, but never more than -5%. I have a battery load tester coming in, so I'm going to check that. I still have the old oxygen sensors. I'm half tempted to at least swap one side to see if it makes a difference. HOWEVER, as I said, on hot starts I do notice that it acts up from time to time, as in it just doesn't crank up the same. Like it starts to fire up too fast or something. So, that leads me to believe the issue isn't actually sensor related. I'm actually starting to wonder if I've got injectors that are bleeding down and leaking. This seems to make sense why the fuel trims are so negative at idle speeds, but seem to even out at higher rpms. I don't want to drop $400+ on new injectors as a guess, but on a stock tune (truck was never tuned), LTFT constantly trying to correct for over-enrichment, it's pointing in that direction. If I were dealing with a leaking manifold, it'd be trying to add fuel, not take it away. Same with a leak at the exhaust manifold or collector. It'd be trying to add fuel, not take it away.
How can I monitor fuel pressure after turning the key off? When using my obd2 scanner, it stops reading as soon as I turn the key to the accessory or off position.
I've added some high doses of techron and redline fuel additive to the fuel tank on less than half a tank in the hopes that maybe there's dirt or something inside some injectors and that stuff would work to clear them out. It's a last ditch, low cost effort.
