The G8 runs on a blended SD (MAP sensor) and MAF tune from the factory. If either sensor fails, the car would still run, but not correctly. As stated, the MAP senses atmospheric pressure, and the MAF senses airflow volume (which can vary based on IAT).
I have noticed that even a well tuned car responds noticeably negative to high humidity. High moisture content in the air seems to affect them more than high temperatures.
'09 PSM G8 GT w/ Premium & Sport packages.
Go: LSX 428 stroker, Manzo 2" Camaro LTs, Kooks 3" mids, GXP axle backs, VCM OTRCAI, RCR AirRam intake & ported TB, PRC CNC LS3 heads w/ LS9 valvetrain, 100mm LS7 MAF, 3.27 gears, Circle-D 3200 stall. Tuned by Me.
Whoa!: CTS-V/ Camaro 4-piston Brembos, Hawk pads, DBA rotors, full Zeta II front and rear suspension swap w/ BMR goodies and BC coil-overs.
Show: LED headlights and fogs, VG Sharkfin, GXP diffuser, 10% tint, de-badged, polished CTS-V wheels.