Originally Posted by Sh0velMan

The engine will go into a 'mode' where it dumps fuel in open loop mode, if you add too many breathing mods without a tune.

The Nismo intakes (that I have) are one mod that if you put it on without a tune, it'll just go full rich, 10.5:1 or whatever the low threshold is on our O2 sensors. Even with their MAF spacers (which are just like the ones AAM includes in their intakes).

Strange, but I think it's a protection mechanism.