Aftermarket Air Filters

[GeneW]

Originally Posted by 1stToyota

In simple terms, when engines were dumb, as with carburetors, they could be fooled by a HP filter, but new cars with OBD-II watching the airflow isn't going to let itself be fooled for long; it'll adjust to anything new that it's seeing, unless tuning is altered.

....not exactly. ECUs are not infinitely adaptable.

When you restrict air flow the computer will adjust mixture, valve and spark timing and other factors, but only up to a point. Once you constrain the airflow sufficiently the ECU will start to bounce close to soft and hard limits, and will eventually throw a trouble code light

Gene.