But, "ECM" should read HO2s and compensate. Gas pedal depression % should be less therefore giving you better mpg. But unless you took readings before and after you will never know. Usually people get less mpg at first because they enjoy the new found engine sound and tend to step on it a bit more. If you were to take a long trip bet your mpg would be better.
agreed, your car with that "intake" is having your 02 sensors (front is an a/f sensor, rear is cat effieciency 02) add more fuel in the fuel trim with your PCM. Your MAF sensor is reading more mass amounts of air and needs to stick between 12.1-18:1 a/f ratio (this ratio is called wideband). Basically, 12 would be rich condition, 18 is lean, 14.7 is stoichiometric (known as balanced). To the :1 is the amount of air to the amount of fuel. With you adding your CAI, the ratio will be slightly richer, since the denser air, but we don't have speed density meters, so in other words, it will increase more power from the power stroke from the engine cycle, but more fuel atomization is needed in the combustion chamber to balance it out. That's the technician explanation
2009 Cobalt LS XFE U74
Mods: K&N Typhoon Intake, Option Cat-Back Exhaust, Cosmo Short shifter, Maxxim Ahead 17X7's, MPx shorty antenna, FE5 Strut/shocks, Tein S Techs, Moog endlinks, Moog spring seaters, ZZP shorty header, LSJ downpipe, LNF front grille