The mixture is set based on feedback from the O2s so get those in, clear codes, find reset adaptations in the third main menu I forget the name.

Watch the fuel trim values live once you get the o2s installed.

Try some up hill WOT (wide open throttle) runs see if you get hesitation.

If so than for sure check fuel pressure under load. (usually a little tricky to do but if the pump is weak, usually some quick punches of the throttle in neutral will show drop in fuel pressure)

The computer knows how many milliseconds of fuel to add based on the metered amount of air so when you get lean operation, usually it's a vacuum leak down stream from the MAF sensor but with no leaks it's a good chance the fuel pump is worn out and can't supply full pressure at high demand.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)