Aftermarket Air Filters

[1stToyota]

Originally Posted by GeneW

....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.

What I was getting at was that taking out a stock air filter and dropping in a hi-flow filter won't do what the box claims, but people will think it's really made a big difference in hp and fuel economy. I try not thinking about it now, but not too long ago a tool salesman that used to come around told me how he installed a K&N drop-in in his late model automatic Dodge truck, and instantly he noticed that it now gets sideways and lights up the rear tires at 55mph.