Chasing the codes - help?

[kiehen]

Hi there. New to BMW, new here. I recently purchased a 2000 540iT Sport with 98k miles on it. I'm not new to working cars. I immediately revamped the cooling system. After that, I started tackling to the check engine light for the too lean codes on both banks (disclaimer, I don't yet have an ISTA setup, hoping to have it up and running this week). Everything points to a big vacuum leak. Long-term fuel trims showing like, 24%. Initial fuel consumption as calculated by the OBC was sky high. Like, 11mpg. I had issues with it just quietly stalling out whenever I came to a stop after it got up to operating temp and intermittently stalling immediately after starting, but only if it was already at operating temp. Immediately addressed a couple old and cracking small vacuum lines. Dealership claims they replaced the rigid hose crank case vent hose that runs under the intake manifold, which obviously means they pulled the intake manifold. That's about all I know on that, but they put the engine cover mounting brackets back on backwards, so low faith. I bought a smoke machine and dug in with that. Intake boot was poorly seated, addressed that and gave it a real good inspection for cracks. Housing for the brake booster check valve had a massive crack. Replaced that. Stalling issue went away, fuel consumption improved, but codes are still active and live data shows the fuel trims are still way up there. I cannot find a wisp of smoke on testing now. Under normal driving conditions, runs and drives like a dream. If I put my foot into it, it bogs down after about 3500 revs. So. I've got the parts ready to go deeper - intake manifold gaskets, throttle body gasket, new PCV plate and gasket, and a replacement for the rigid hose the dealership supposedly replaced. I've also got a fuel filter coming, since I have no idea when that was done last, if ever. Looking for some ideas here in case I missed something simple before I dive into the manifold.

Thanks in advance!

Pic of my new obsession attached.

[KeviKev]

Very nice, I’d love to own one of those. I’ve had a 2002 540i 6 speed for a daily driver for 13 years. I’ve just joined this forum, so if you still need advice/help let me know. I’ll do what I can.