Hello, all, newer fit and even Honda owner. I have a 2009 GE8, I installed a less restrictive exhaust ( 2 1/4“ pipe and no resonator nor muffler ) all was good, no codes. I installed an Amazon “CAI” and then popped a lean code, now I expected this and I do have half a brain and know increasing air but not fuel will cause your engine to run lean. My question is, while I’m trying to find a tuner, will a lean code by itself disable VTEC in the L15A7? I do feel the RPMS climb faster around the 4500 to 5800 rpm range but not hearing cross over. Which I did used to hear although it was subtle.

 

Yes, trouble codes can disable VTEC.
The Mass Air Flow sensor is mostly measuring the speed and temperature of the air passing over it. To figure out the quantity of air entering the engine, the ECM needs to know how big the tube is where the MAF is installed. Since nobody but pesky tuners will try to change out that tube, the size is hard-coded in the ECM programming. Just plopping the sensor into a bigger tube will mean slower air speed for a given actual quantity of air. Slower air speed means the ECM thinks there's less air entering the engine, so it injects less fuel and ends up with a lean air/fuel mixture.
You need an intake with the proper size MAF passage. Or, like... a tunable MAF? Not sure if that's a thing.