Intermittent SES / fuel trim codes

[RocketyMan]

At first glance, that would def seem too much. But I never really experimented with the flowrate of the AC compressor on, fan, blower, etc. when the engine is under any load.

Doing some maths, the 7.28g/s would suggest idling at about 1200 rpms, but I didn't see anywhere in the OP that he reported the idle speed with that flow rate as it could've been reported on a cold engine with startup...I dunno. I guess I'd have to assume the idle was at 750 rpms re-reading that post.

The 4.48g/s suggest idle of around 750 rpms. That seems perfect, but a good self check would be to take it to several rpm points like 1500, 2000, etc, and determine if the reporting follows a linear fashion.

[rmr2122]

I reinstalled the original BMW Siemens MAF and the SES light has not returned in over 1000 miles of driving. I’ll be returning the VDO unit to FCP.

[PaulyMcBee]

2004/11 BMW X5 e53 3.0L M54:
Ongoing symptoms: No performance/drivability issues. Intermittent SES / CEL with OBD codes P1092 & P1093 and INPA code 235 (lambda sensors).

Verified no vac or compression leaks (smoked engine; cylinders leak check; cylinders compression check; radiator pressure check; fuel pump & brake booster leak checks)

Replaced (MAF; plugs; all four O2 sensors; plugs; hoses; gaskets)

Fix that worked...switched fuel to non-ethanol type. Suspect the higher heat from more volatile ethanol throws sensors off just enough.
Verified this works/cures issue by alternating fuel types. As soon as I start using normal ethanol fuel, the codes return. When I start adding VP racing fuel to the tank, the codes disappear. This is totally f$@ked, as such fuels are not permitted on the road anymore due to politically correct fuel regulations.