I've started driving my '01 a bit more this past week, starting off by getting the annual safety/emissions inspection. I scanned it for codes prior to the inspection, and only had one for the passenger airbag (wouldn't clear, after inspected), and none for the remainder of the systems.
I made three more 20+ mile trips later, and on the second one I got the Service Engine Soon light, about two miles from home. I checked it with the Foxwell NT510E first, then with my Innova 3100i scan tools; both showed P0171 & P0174 (lean misfires banks 1 & 2). I hadn't noticed any stumble or such while driving (I'm very sensitive to those, after 50+ years tuning by vacuum gauge & feel-of-the pants driving perceptions). I dismissed them/cleared the codes as glitches, since there had been no problems a day earlier, or at the inspection three days prior.
On my last trip, I was watching out for anything amiss, and saw the SES light come on at the same spot as I neared home (a hard right turn after hard braking, due to tail-gating traffic). Still no driveability problems. This time there was an added P0313 code (misfire detected with low fuel), and I detected a whiff of oil smell under-hood (never before; no obvious valve cover leaks). I looked at the freeze frame on the Innova, which showed the rpm as 2811, consistent with the hard turn SES activation situation. I was going to take a photo of the freeze frame, but didn't have my phone handy, and just cleared the codes and moved on to diagnose two DTC's on my wife's HHR Panel (TPMS warning...three sensors gone dark, and passenger seat airbag warning...from a spilled vase of flowers saturating it), before she went out of town overnite.
I plan to get a fog/smoke machine, replacement vacuum gauge & tester kit (I lent mine out awhile back), Mass Air Flow sensor cleaner, and utilize my inspection camera to try and detect any vacuum leaks, next week. I'll also inspect the CCV system, which may be original to the car, and 20 years-old (a previous once-over detected no mayo under the cap, nor loss of oil, nor cracked hoses).
Since I'm new to the BMW, with all the "modern" tech to decipher, should I look at any other spot while I'm searching for anything amiss?